School Science Lessons
Topic 16 Organic chemistry, tests for organic compounds
2012-01-25 SP
Please send comments to: J.Elfick@uq.edu.au
See: IUPAC, Nomenclature of Organic Chemistry (website)
See: Interesting websites
Table of contents
16.1.0 Organic chemistry
16.1.5.7 Acid anhydrides, acyl anhydrides, anhydrides, [RCO-O-COR' (R(C=O)O(C=O)R')]
16.1.5.5 Acyl halides, group: (-CO.X), X = halogen atom, acid chloride, acid chlorides group: (-COCl), Suffix: -oyl, chloride
16.1.5.6.1 Acrylamide, 2-propenamide, ethylene carboxamide, acrylic amide, vinyl amide
16.1.1 Acyclic hydrocarbons, alkanes, alkenes, alkynes
16.1.01 Addition reactions
16.1.3.0 Alcohols, phenols, thiols, ethers, epoxy compounds, acetates, (ethanoates), benzoyls, acetals
16.1.3.1a Alcohol, Ethanol safety
16.3.1.0 Aldehydes, ketones, quinones, Aldehydes group: -CHO, Suffix: -al
16.1.5.6 Amides, acid amides group: (-CONH2, RCONH2), Suffix: -amide
16.1.5.6.01 Physostigmine
16.2.4.3 Amines, aliphatic amines, (RNH2-), R = alkyl group, ionization reaction of methylamine
16.2.3.1 Carbides (C4-), (carbon + metal)
16.3.8.0 Carboxylic acids and fatty acids
16.4.1.01 Carbonyls
16.2.4.3.2 Chloramines
16.2.10 Coal tar products, creosote
16.2.4.2.1 Cyanamides, inorganic, (CN22-), ionization reaction of methylamine, cyanic acid, melamine
16.2.4.7 Cyanocrylates [(CH2)C(CN)COOR], "Superglue"
16.4.4 EDTA, ethylenediaminetetraacetic acid, C10H16N2O8
16.5.1.0 Esters, derivatives of fatty acids (RCOOR'), esters group: (-COOR), Suffix: (-oate)
16.1.1b Ethane, (C2H6), prepare ethane
16.2.4.3.1 Ethylenediamine
16.3.5.0 Fluorescent liquids
16.2.2 Halogen compounds, haloalkanes, (alkyl halides), halogen derivatives
1.0 Chlorine
2.0 Iodine
3.0 Bromine
4.0 Fluorine
16.1.5.8 Imides, imido group: (-CONHCO-), (R1CO-NH-COR2)
16.2.4.3a Imines, imino group: -NH- in a ring, or =NH
16.2.4.2 Nitriles (acid nitriles, alkyl cyanides, cyanides), (-CN, RC=-N), Cyanide ion: CN-
16.2.4.5 Nitrites, (NO2-), dioxonitrate ion, salts or esters of nitrous acid, (O=NOH), Nitrites group: -C=N, Suffix: -nitrite
16.2.4.4 Nitroalkanes, (nitroparaffins), (CnH2n+1NO2)
16.2.4 Nitrogen compounds, one atom of nitrogen
16.2.5 Nitrogen compounds, two or more nitrogen atoms
16.2.5.1 Azide compounds
16.2.5.2 Azo compounds
16.2.5.3 Diazo compounds
16.2.5.4 Phenylhydrozone compounds
16.2.3 Organometal compounds, prefix the metal with: organo-
16.1.03 Oxidation reactions, loss of electrons
16.2.4.6 Oximes (hydrox-imino-alkanes), Group: (C:NOH)
16.2.6 Phosphorous compounds, organophosphorus insecticides
16.1.00 Prepare organic compounds: addition, substitution, oxidation, reduction reactions
3.32.0 Prepare gases with a gas generation apparatus
16.6.1.1 Proteins, peptides, amino acids
16.1.5.3 Salts, organic salts, e.g. sodium ethanoate, (sodium acetate, CH3COONa), (ammonium acetate, CH3COONH4)
16.2.8 Sulfur compounds
16.4.5.0 Tests for organic compounds
16.1.1 Acyclic hydrocarbons
16.1.1 Acyclic hydrocarbons, alkanes, alkenes, alkynes
16.1.1.1 Alkanes, (CnH2n+2), paraffins
16.1.1.1b Arenes
16.1.1.1b Benzene
16.1.1d Butane (C4H10), prepare butane, combustion of butane
16.1.1.1a Cycloalkanes
16.1.1b Ethane, (C2H6), prepare ethane
16.1.1f Hexane, (C6H14)
16.1.1g Heptane, (C7H16)
LPG (liquefied petroleum gas, LP gas)
16.1.1a Methane, (CH4), prepare methane gas
16.1.1a.01 Methane, Prepare methane gas
16.1.1a.2 Methane with chlorine
Natural gas
Natural gas (Methane)
16.1.1h Octane, (C8H18), octane number
16.1.1e Pentane, (C5H12)
16.1.1c Propane, (C3H8)
3.39.1 Reaction of methane with steam
3.41.4 Reduce copper oxide with natural gas, methane
16.1.1a.02 Tests for methane gas, burn methane
16.1.1.2 Alkenes, (CnH2n), olefins
16.1.1.2.1 Prepare ethene, (ethylene), C2H4
16.1.1.2.2 Dienes, isoprene units
16.1.1.3 Alkynes, (CnH2n-2), acetylenes
16.1.1.3.1 Prepare acetylene, (ethyne)
16.4.6 Tests for gases from burning hydrocarbons, oxyacetylene welding
16.1.1.1b Arenes, benzene
16.1.1.1d Friedel-Crafts reaction
16.1.1.1c Nitration
16.1.3.0 Alcohols, phenols, thiols
16.1.3.0 Alcohols, phenols, thiols, ethers, epoxy compounds, acetates (ethanoates), benzoyls, acetals
16.1.3.A Propanol, propyl alcohol, (C3H7OH)
16.1.3.B Butanol, butyl alcohol, (C4H9OH)
16.1.3.0.1 Dihydric alcohols, glycol
16.1.3.0.2 Trihydric alcohols, glycerol
16.1.3.0.3 Nitroglycerine (UK), nitroglycerin (USA)
12.12.4 Oxidation of glycerol by potassium permanganate
16.1.3.1.1 Alcohols, primary, secondary and tertiary aliphatic alcohols, rubbing alcohol
16.1.3.1.2 Prepare sodium ethoxide
16.1.3.2 Phenols, group: (OH-C), in a benzene ring, Phenol = (C6H5O6)
19.1.0.4 Polyhydric alcohols
16.1.3.2a Pyrogallol
16.1.3.2.1 Carbolic acid, phenol, TCP, Dettol
16.1.3.2.2 Naphthols
16.1.3.2.3 Cresols
16.1.3.2.4 Resorcinol
16.1 3.2.5 Triclosan, organohalogens
16.1.3.3 Thiols, mercaptans, thio alcohols, Thioalcohols group: (-SH), Suffix: (-thiol), (SH in an organic compound)
16.1.3.4 Ethers, group: (-O-), in organic compound
3.4.3.1 Epoxy compounds, (O atoms in CCO ring), Epoxy resin polymers, thermoset plastics
16.1.3.6 Acetates, (ethanoates), ROAc
16.1.3.7 Benzoyl group, benzene carbonyl group: (C6H5CO-)
16.1.3.8 Acetals, (alcohol + aldehyde), RCH(OR')2
16.1.12 Fractional distillation of crude oil
16.1.13 Prepare triodomethane, (iodoform)
16.1.14 Prepare trichloromethane, (chloroform)
16.1.12 Fractional distillation of crude oil
16.1.12 Fractional distillation of crude oil
16.1.12.1 Petroleum gas, (methane, ethane, propane, butane), LPG
16.1.12.2 Naphtha, (ligroin), processed to make gasoline
16.1.12.3 Petrol, "gas", gasoline, motor fuel
16.1.12.4 Kerosene, kerosine, paraffin oil, jet engine fuel, tractor fuel
16.1.12.5 Diesel oil, gas oil or diesel distillate, diesel fuel, heating oil
16.1.12.6 Lubricating oil, motor oil, grease
16.1.12.7 Paraffin wax, heavy gas, fuel oil
16.1.12.8 Residuals, bitumen, "tar", asphalt, waxes, petroleum jelly
16.2.8 Sulfur compounds
16.2.8 Sulfur compounds, (For the "thio" prefix, replace oxygen by sulfur, e.g. thiobenzamide [PhC(=S)NH2])
16.2.8.1 Isothiocyanates, (old name: mustard oil), (RN=C=S), Mustards: [X(CH2.CH2)2S]
16.2.8.2 Sulfides: RSR, (R not equal to H), Old name: thioethers
16.2.8.3 Sulfonic acids, group: R-SO2OH, e.g. methanesulfonic acid, CH3SO2OH, Salts or esters: sulfonates
16.2.8.4 Sulfonium compounds: R3S+, e.g. trimethylsulfonium chloride [(CH3)3S]+Cl-
16.2.8.5 Thiocyanates: [RC(=O)SN], Salts and esters of thiocyanic acid, HSCN, e.g. methyl thiocyanate (CH3SC =-N)
16.2.8.6 Silicones: polymeric unbranched siloxanes, Formula: (-OSiR2-)n, (R not equal to H)
16.2.8.7 Siloxanes
16.2.8.9 Sulfoxide, e.g. dimethyl sulfoxide, DMSO, (CH3)2SO, C2H6OS, propanethial S-oxide
16.1.3.3 Thiols, thio-alcohols
16.3.1.0 Aldehydes, ketones, quinones
16.3.1.0 Aldehydes, ketones, quinones, Aldehydes group: (-CHO), Suffix: (-al)
16.3.1a Aldehydes, alkanals, (aliphatic aldehydes), ketones, quinones
Metaldehyde
16.3.1 Prepare ethanal, (acetaldehyde), with potassium dichromate
16.3.2 Prepare ethanal with potassium manganate (VII), (potassium permanganate, Condy's crystals)
16.3.3 Oxidation of methanol to methanal using platinum catalyst
16.3.7.2 Oxidation of glucose with sodium hydroxide and methylene blue, blue bottle experiment
16.3.7.3 Silver mirror tests for aldehydes, Tollens' test
16.3.7.0 Fehling's tests for aldehydes in solution
16.3.7.1 Reducing sugars and nonreducing sugars
16.3.8 Ketones, Group: (>C=O), Suffix: -one
16.3.9 Diacetyl, 2,3-butanedione
16.3.10.0 Quinones
16.3.10.1 Pindone
9.140 Tests for reducing sugars and aldehydes, tests for simple sugars, Fehling's test
16.3.5.0 Fluorescent liquids
16.3.5.1 Aesculin, (Escalin)
16.3.5.2 Amido phthalic acid and amido-tarephthalic acid
16.3.5.3 Eosin, (Eosine)
16.3.5.4 Fluorescein
16.3.5.5 Fraxin
16.3.5.6 Magdala red
16.3.5.7 | Quinine
16.3.5.8 Safranin, (safranine, safranin O, basic red 2)
16.4.5.0 Tests for organic compounds
9.137 Tests for fats and oils
16.4.6 Tests for gases from burning hydrocarbons, oxyacetylene welding
16.4.1 Tests for organic acids and alcohols
16.4.5 Tests for proportion of fats in foods
16.4.7 Tests for saturated hydrocarbons, the bromine water test
16.4.8 Tests for saturated hydrocarbons, alkaline potassium manganate (VII) solution
16.4.9 Tests for saturated hydrocarbons, acidified potassium manganate (VII) solution
16.1.0 Organic chemistry, preparing different compounds
See diagram 16.0.0: Organic chemistry functional groups | See diagram 16.0.1: Tetrahedral geometry of carbon, methane molecule, isobutyl alcohol
Organic chemistry is the chemistry of carbon compounds. Hydrocarbons contain carbon and hydrogen only. The main types are the alkanes, alkenes and alkynes. In alkenes and alkynes, addition reactions occur at the double bond or =-s bond.
Be careful! When heating organic chemicals, do not point the test-tube towards anyone! Organic compounds may suddenly vaporize and spurt out of the test-tube!
1. Classification by molecular framework
1.1 Acyclic compounds have chains of unbranched or branched carbon atoms
1.2 Carbocyclic compounds have rings of carbon atoms
1.3 Heterocyclic compounds have rings of carbon atoms with one atom in a ring not carbon, e.g. O, N, S
2. Classification by functional group, e.g. hydroxyl group, OH, is characteristic of alcohols
16.1.00 Prepare organic compounds
16.1.01 Addition reactions
Atoms are added to the two atoms of a double bond or triple bond in an unsaturated compound, also when no atoms are replaced but extra covalent bonds are formed
alkenes (olefins) or alkynes (acetylenes) --> haloalkanes (alkyl halides), or primary alkanols (alcohols), or secondary alkanols (alcohols)
Example: HCl + CH2CH2 --> CH3CH2Cl
16.1.02 Substitution reactions (displacement reactions)
Replacement of an atom or group in a molecule by another atom or group
alkanes (paraffins) --> haloalkanes (alkyl halides) --> amines
haloalkanes (alkyl halides) <--> primary alkanols (alcohols), (-CH2-OH)
alkanoic acids --> esters --> amides
Example: CH4 + Cl2 --> CH3Cl + HCl [chlorination produces chloromethane (methyl chloride) and HCl.]
16.1.03 Oxidation reactions - loss of electrons
primary alcohols can be directly oxidized to aldehydes or carboxylic acids
primary alkanols (alcohols), (-CH2-OH) --> alkanals (aliphatic aldehydes)
Example: CH3OH + ˝ O2 --> CH2O + H2 (Pt catalyst) [Oxidation of methanol to methanal using a platinum catalyst]
alkanals --> alkanoic acids, e.g. butanoic acid, CH3(CH2)2COOH
secondary alkanols (alcohols), (CH3)2CHOH --> alkanones
16.1.04 Reduction reactions - gain of electrons
alkanals (aliphatic aldehydes) --> primary alkanols (alcohols), (-CH2-OH)
Example: Add drops of formalin to a test-tube one quarter filled with Fehling's A and B solutions and heat to boiling. Note the yellow then orange then red precipitate of copper (I) oxide. The copper from the copper (II) sulfate solution has been reduced from copper (II) to copper (I).
16.1.1 Acyclic hydrocarbons, alkanes, alkenes, alkynes
See diagram 16.1.1: Alkanes, alkenes, alkynes | See 10.6.3: Distil crude oil and collect the fractions
Alkanes, alkenes, alkynes or their derivatives are aliphatic compounds, i.e. non-cyclic organic compounds. Acyclic molecules have carbon atoms in chains but not in rings. The chains may be unbranched or branched. Aromatic compounds contain a benzene ring in the molecule. Hydrocarbon compounds contain only hydrogen and carbon. Hydrocarbons are usually colourless and have low solubility in water. Crude oil is a mixture of hydrocarbons.
Hydrocarbons may be saturated, i.e. have only single bonds, or unsaturated, i.e. contain multiple bonds, e.g. double bond, triple bond,
The iodine value is the number of grams of iodine absorbed by 100 g of fat or oil to indicate the amount of unsaturated acids.
16.1.1.1 Alkanes (CnH2n+2), paraffins
The first 10 unbranched alkanes and molecular formula: methane (CH4), ethane (C2H6), propane (CH3H8), butane (CH4H10), pentane (CH5H12), hexane (CH6H14). heptane (CH7H16), octane (CH8H18), nonane (CH9H20), decane (CH10H22). Alkanes burn in oxygen to give carbon dioxide and water. Candle wax is a mixture of different alkanes that are solid at room temperature. Alkanes are usually associated with natural petroleum deposits and can be distilled from petroleum.
1. Alkanes (paraffins) are saturated hydrocarbons, i.e. all single bonds between C atoms, have formula CnH2n+2 and names end in "ane". The names of unbranched alkanes come from the number of carbon atoms. The name of branched alkanes come from the longest chain of carbon atoms. The hydrocarbon branches, alkyl groups, symbol R, are formed by removing one hydrogen atom from the alkane and named by changing the "ane" to "yl", e.g. methane, CH4 to methyl, CH3-, also "Me". The carbon atoms of the longest continuous name are numbered starting at the end of the chain closest to the first branch, e.g. an eight carbon chain with an ethyl group attached to carbon 5 and a methyl group attached to carbon 3 and carbon 4 is called 5-ethyl-3, 4-dimethyloctane.
16.1.1.1a Cycloalkanes
Cycloalkanes are saturated hydrocarbons with a ring of carbon atoms, e.g. cyclopropane (the simplest) cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane. The position of branches depends on the alphabetical order of the branch names so that highest in order is attached to carbon 1, e.g. 1-ethyl-2-methylcyclopropane.
16.1.1.1b Arenes, benzene
See 16.3.4.0: Aromatics, aromatic compounds, benzene derivatives, arenes
See diagram 16.8.1: Benzene compounds
Arenes, e.g. benzene, naphthalene, anthracene, phenanthrene. Arenes do not mix with water, but they do mix with hydrocarbons and all non-polar solvents. Arenes usually burn with a smoky flame, as do most aromatic compounds, because of the high carbon: nitrogen ratio. So when they burn in air, some carbon soot usually remains in the air.
Benzene, C6H6, has a stable six-sided ring structure.
Arenes are called aromatic compounds because the first arenes were isolated from fragrant oils. However, nowadays aromatic refers to the structure not the smell.
16.1.1.1c Nitration
The reaction substitutes a hydrogen atom in an arene ring by a -NO2 group. For example:
Heat benzene with a mixture of nitric and sulfuric acid catalyst  in a Liebig condenser at 330 K.
benzene + HNO3 --> benzene-NO2 + H2O
benzene + NO2+ --> benzene-NO2 + H+
Also, some 1,3-dinitrobenzene may form.
16.1.1.1d Friedel-Crafts reaction
The reaction substitutes a hydrogen atom in an arene ring of a halogenalkane by an organic group, R, using aluminium chloride catalyst.
RCl +AlCl3 --> R+ + AlCl4-
For example, benzene with chloromethane forms methylbenzene.
benzene + CH3+ --> benzene-CH3 + H+
CH3Cl +AlCl3 --> CH3+ + AlCl4-
16.1.1a Methane (CH4), prepare methane gas
See diagram 16.0.1: Tetrahedral geometry of carbon, methane molecule, isobutyl alcohol
Methane is the simplest alkane. It is colourless and odourless and found in natural gas and bubbles of methane in swamp water. Fire damp, which causes explosions in coal mines, is a mixture of methane and air. Methane is found in large quantities usually associated with petroleum. It has largely displaced town gas produced from coal. Methanogenic bacteria live in swamps and in the human gastrointestinal tract where they liberate methane causing flatulence. After carbon dioxide, methane produced by bacteria in rice paddies may be the second most important greenhouse gas made by man. They produce methane gas anaerobically (without oxygen) by removing the electrons from hydrogen gas. The electrons and H+ ions from hydrogen gas are used to reduce carbon dioxide to methane. H+ ions combine with the oxygen from carbon dioxide to form water and electrons move through the steps of an anaerobic electron transport system to the phosphorylate of ADP to form ATP. Methane, is a simple asphyxiant.
16.1.1a.01 Prepare methane gas
See diagram 3.32: Collect insoluble gases over water
Heat 20 g of sodium acetate-3-water in a Pyrex test-tube until the salt becomes anhydrous. Grind the cooled salt with an equal amount of soda lime [NaOH + Ca(OH)2] granules in a mortar and pestle. Mix thoroughly and place the mixture in a Pyrex test-tube. Heat the test-tube and collect the gas over water.
Be careful! If you do not pull out the delivery tube, heating the water stops or the water will be "sucked back" into the hot test-tube! For safety, wrap the test-tube in wire gauze.
CH3COONa + NaOH --> CH4 + Na2CO3
sodium acetate + sodium hydroxide --> methane + sodium carbonate
16.1.1a.02 Tests for methane gas, burn methane
Light the gas in the test-tube with a glowing splint. The gas burns with a clear flame.
CH4 + 2O2 --> CO2 + 2H2O
3. Repeat the experiment using glacial acetic acid soaked in glass wool + soda lime.
16.1.1a.2 Methane with chlorine
When a mixture of an alkane and chlorine gas are stored at low temperature in the dark no reaction occurs. At high temperatures or in sunlight, a substitution exothermic reaction called chlorination occurs to produce chloromethane, methyl chloride and HCl.
CH4 + Cl2 --> CH3Cl + HCl
Excess chlorine can produce dichloromethane (methylene chloride) trichloromethane (chloroform) and tetrachloromethane (carbon tetrachloride).
A mixture of chlorine and methane explodes violently in direct sunlight forming hydrogen chloride and free carbon.
BE CAREFUL! Do not mix chlorine and methane!
CH4 (g) + 2Cl2 (g) --> C (s) + 4HCl (g) + energy
16.1.1b Ethane (C2H6), prepare ethane
Colourless and odourless gas which has properties similar to methane.
See 3.32.0: Prepare gases with a gas generation apparatus | See diagram 16.1.1: Ethane
Collect insoluble gases over water. (This experiment was called the "wet asbestos method" because asbestos wool, now not allowed in schools, was used to soak up the methyl iodide in the test-tube.)
Pour 2 cm methyl iodide in a test-tube. Add 5 g of copper turnings and push it down firmly with a spatula. Set up the apparatus and heat the mixture.
2CH3I + 2Cu --> C2H6 + Cu2I2
16.1.1c Propane (C3H8)
Colourless liquefied petroleum gas, a bottled gas, b.p. -42.2oC, catalytic cracking forms propylene
16.1.1cc LPG (liquefied petroleum gas, LP gas)
LPG is a clean burning fuel and is stored in gas cylinders as bottled gas. LPG is a simple asphyxiant. It consists of propane (about 95%) together with varying proportions of butane, propylene and butylene. A rank smelling compound is added so that the presence of the gas can be easily detected. Incomplete combustion forms carbon monoxide. Do not search for a gas leak with a lighted match or lighted taper. Use a soap solution.
16.1.1d Butane (C4H10), prepare butane, combustion of butane
b.p. -0.5oC, relative density 0.60 at 0oC, is stored as liquid under pressure in steel cylinders giving Calor gas and cigarette lighter gas, cigarette lighter fuel is 90% butane, isomer isobutane.
See diagram 3.32: Collect insoluble gases over water, See 3. | See diagram 16.1.1: Butane formula
(This experiment was called the "wet asbestos method" because asbestos wool, now not allowed in schools, was used to soak up the ethyl iodide in the test-tube.)
Pour 2 cm ethyl iodide in a test-tube. Add 5 g of copper turnings and push it down firmly with a spatula. Set up the apparatus and heat the mixture.
2C2H5I + 2Cu --> C4H10 + Cu2I2
Combustion of butane
See pdf Butane  / Oxygen combustion
2C4H10 + 13O2 --> 8CO2 +10H2O + energy
16.1.1e Pentane (C5H12)
b.p. 36.3oC, relative density 0.63, is made by distillation of petroleum.
16.1.1f Hexane (C6H14)
b.p. 68.7oC, relative density 0.66, exists as five compounds with same formula, normal hexane, n-hexane, in petrol and petroleum ether solvent, colourless liquid ethereal odour. "Shellite" (Australia) is 60% hexane and 40% heptane.
16.1.1g Heptane (C7H16)
b.p. 98oC, relative density 0.68, nine isomers, normal heptane has similar properties to normal hexane.
16.1.1h Octane (C8H18), Octane number
See diagram 16.1.1h: Octane number: n-butane, propane, butene-1, cyclopentane, propylene, benzene, 0-xylene, toluene
b.p. 126oC, relative density 0.702 at 20oC, exists as eighteen compounds, in petroleum. Isomeric with iso-octane, 2, 2, 4-trimethylpentane (CH3)3CCH2CH(CH3)2.
Octane number
See: 32.5.5.5: Spark plugs, pre-ignition
Some hydrocarbons with unbranched carbon chains prematurely explode in the cylinder and produce an audible knocking sound or "ping" sound (knocking, pinking). A scale of "knock property" has isooctane (2, 2, 4-trimethylpentane) at 100 (a good fuel) and heptane at 0 (a poor fuel). So gasoline with octane number 80 has the same properties as a mixture of 80% isooctane and 29% heptane. Octane number is the percentage of iso-octane normal heptane mix with the same knocking behaviour of the fuel being tested, so it indicates the knock rating of a motor fuel. A high octane fuel has a longer self-ignition delay in a motor car engine. In Brisbane, most " family cars" use 91 octane "unleaded petrol". This is the lowest octane rating of the different petrols sold in garages.
A high octane rating of a fuel means that it has less tendency to pre-ignite in a high compression engine. Pre ignition means that, before the spark plug has fired, the fuel air mixture burns because of the heat created in the cylinder by compression. Unleaded petrol has the octane rating 98.
Engine compression ratio 4:1 5:1 6:1 7:1 8:1 9:1 10:1 11:1 12:1
Octane number to be knock-free 60 73 81 87 91 95 98 100 102
16.1.1.2 Alkenes (CnH2n), olefins
ethene (ethylene), (H2C=CH2), amylene, propadiene (allene), (R2C=C=CR2), dienes buta-1, 2-diene (CH3CH=C=CH2), amylene
See diagram 16.1.1: Cyclodienes, cis-trans alkenes
1. Suffix: -ene for C=C (olefin, olefins, olefines) are unsaturated hydrocarbons with at least one double bond between C atoms, C=C, have formula CnH2n. Alkenes include ethene (ethylene, C2H4, CH2=CH2), ethenyl (vinyl CH2=CH-), 3-propenyl (allyl, CH2=CH-CH2-), e.g. vinyl chloride (chlorethene, CH2CHCl), allyl chloride (3-chloropropene CH2=CH-CH2Cl). (In the textile trade "olefin" refers to synthetic fibre, polyolefin fibre, that are long-chain polymers of ethylene or propylene, i.e. polyethylene (polypropylene, PP). Alkenes decolorize acidified potassium permanganate solution and bromine solution.
2. The cycloalkenes, cycloolefins, are closed chain, non-aromatic forms, e.g. cyclopropene, CH.CH.CH2, cyclobutene, cyclopentene, cyclohexene.
16.1.1.2.1 Prepare ethene (ethylene), C2H4
See 3.32.0: Prepare gases with a gas generation apparatus
The preparation is an example of the dehydration of an alcohol.
1. Slowly add 10 mL of concentrated sulfuric acid to 5 mL of ethanol and 1 g of powdered aluminium sulfate in the gas preparation apparatus. Be careful!
Pass the gas formed through sodium hydroxide solution to remove sulfur dioxide and carbon dioxide. Collect the gas over water. Heat only if necessary. Pass through sulfuric acid as dehydrating agent.
CH3CH2OH -> H2C=CH2 + H2O
2. Add 3 mL ethanol to a plug of glass wool in a boiling tube. Cover the glass wool with porous pot and heat the porous pot.
C2H5OH --> C2H4 (g) + H2O
3. Prepare ethene (ethylene) with ethanol, breakdown of ethanol to ethene (ethylene, H2C=CH2).
See 3.96: Breakdown of ethanol to ethene (ethylene)
Alkanes (paraffins) are saturated hydrocarbons.
Ethene (ethylene, H2C=CH2), gas is a plant growth substance. It is produced in wounded, diseased and ripening tissues where it reacts with auxins to induce fruit ripening and abscission of leaves or diseased parts. It is used to ripen stored fruit artificially, e.g. bananas.
Put some cleaned and dried unglazed porcelain chips in a flask. Add 10 mL of pure ethanol (absolute alcohol). Slowly pour 30 mL of concentrated sulfuric acid down the sides of the flask. Be careful! Shake the flask gently under cool water to avoid alcohol being carbonized because of increase in temperature. Fit the flask with a thermometer and a delivery tube inserted in a two-holes rubber stopper. Heat the flask to raise the temperature quickly to 170oC, then control at 170oC. This heating procedure is used to increase the use ratio of ethanol and decrease by-products. Wait until exclusion of the air in the flask and then collect the produced ethene gas over water. Concentrated sulfuric acid and sodium hydroxide solution can be used to absorb and remove the small quantities of the ethyl ether (sulfuric ether) vapour, carbon dioxide and sulfur dioxide present in the produced ethene.
C2H5OH (l) -> C2H4 (g) + H2O at 170oC.
4. Prepare ethene (ethylene), with ethanol, alternative method
See diagram 16.10.3: Prepare ethene
Absorb ethanol in cotton wool and push this to the bottom of a hard glass test-tube. Pack small pieces of unglazed porcelain in the middle of the test-tube. Fit a delivery tube to collect ethene gas over water. First heat the porous pot strongly and then heat gently the cotton wool to produce some ethanol vapour. This vapour breaks down over the hot porous pot to produce ethene gas and water vapour. The temperature should be above 170oC otherwise the reaction produces dimethyl ether. Collect the ethene over water. Be careful! Disconnect the delivery tube when you stop heating, to avoid a suck back of water onto the hot porous pot.
16.1.1.2.2 Dienes, isoprene units
See diagram 16.1.1.2.2: Isoprene
1. Dienes are alkenes with two double bonds in the molecule.
2. Cumulated dienes have double bonds next to each other.
3. Conjugated dienes have 2 double bonds separated by a single bond:
buta-1,3-diene (CH2:CH.CH:CH2)
Isoprene, 2-methyl-1,3-butadiene, CH2:C(CH3)CH:CH2
4. Cyclodienes
1,3-cyclohexadiene
1,4-cyclohexadiene
5. The 5-carbon isoprene units in natural products have a four carbon chain and a one carbon branch at C2, i.e. [C(CC)CC]
Terpenes have linked isoprene units as in natural rubber.
Rosin is a solid amber residue made by the distillation of turpentine using pine stumps. Natural turpentine contains the terpene called pinene, C10H16.
16.1.1.3 Alkynes (CnH2n-2), acetylenes
1. acetylenes: ethyne (acetylene), (C2H2 (HC =-CH), isoprene, methylene
Suffix: (-yne), for (C=-C), (acetylenes), are unsaturated hydrocarbons with at least one triple bond (=-), between C atoms, include ethyne (C2H2), acetylene, (HC=-CH), 3-propargyl (propargyl), (HC=-C-CH2-). Alkynes decolorize acidified potassium permanganate solution and bromine solution.
2. The cycloalkynes, are closed chain, non-aromatic forms, e.g. cyclooctyne, C8H12 (the smallest form).
16.1.1.3.1 Prepare acetylene, (ethyne)
See diagram 16.1.5: Prepare ethyne
The main hazard with calcium carbide is the ignition of air / acetylene mixtures. A violent explosion may occur, depending on the proportions of air and acetylene. Acetylene, when undiluted with air, burns with a smoky flame. Before igniting acetylene, be sure that it is not mixed with air. Commercial calcium carbide usually contains sulfur and phosphorus compounds that react with water to form strongly smelling gaseous impurities that act as a convenient indicator for the presence of acetylene.
1. In a fume cupboard, put a 2 g lump of calcium carbide in a 250 mL beaker. Add water drop-by-drop. Calcium carbide reacts vigorously with water forming acetylene gas (ethyne) and releasing a considerable amount of heat. Ignite the resulting bubbles of acetylene.
2. On a metal tray or shallow container in a fume cupboard, add water drop-by-drop to one lump of calcium carbide. The water will hiss and the gas will be produced. The lump will fall to pieces to form a powder of calcium hydroxide. Do not attempt to ignite the acetylene produced.
3. Put a < 5 g lump of solid calcium carbide in 500 mL of water and ignite the ethyne produced. Do this experiment outside, with the observers at least 2 metres away.
4. Formerly, bicycle "carbide lamps" used the following reaction. Put sand in a dry test-tube and add pieces or lumps (not powder) of calcium dicarbide (calcium carbide). Add water drop by drop. Collect the gas over water.
CaC2 + 2H2O -> C2H2 + Ca(OH)2
calcium dicarbide + water -> ethyne (acetylene) + calcium hydroxide
5. Collect acetylene from oxy-acetylene equipment
5. Tests for acetylene, (ethyne): Light the gas in the test-tube with a glowing splint. The gas burns with a smoky flame.
16.4.6 Tests for gases from burning hydrocarbons, oxyacetylene welding
Hydrocarbons burn in excess air to form carbon dioxide and water. The reaction is exothermic. Methane burns with a clear flame. Ethene (ethylene) and ethyne (acetylene) burn with a smoky luminous flame. This flame can be seen above a chimney at many petrol refineries where excess ethene is burned off.
Light a natural gas burner or pour drops of cigarette lighter fuel in an evaporating basin and ignite it. Hold a dry test-tube containing ice over the burning gas. Water from the combustion condenses on the test-tube. Add limewater and shake. The milky precipitate shows the presence of carbon dioxide.
CH4 (g) + 2O2 (g) ---> CO2 (g) + 2H2O (g)
In insufficient oxygen, the poisonous gas carbon monoxide forms.
2CH4 (g) + 3O2 (g) ---> 2CO (g) + 4H2O (g)
Oxyacetylene welding (oxy-acetylene welding)
In excess air, acetylene (ethyne) burns with a hot white flame. If the acetylene is mixed with oxygen from separate gas cylinders in an oxy-acetylene torch, a temperature of 3 500oC can be produced to allow welding of tubes and pipes. The two ends of the metal objects to be welded are heated until they begin to melt. Rods of "filler" metal are melted along the joint then the joint cools and solidifies. The oxyacetylene flame can burn under water. Also, metal can be preheated with the oxyacetylene flame then cut with a pure oxygen flame.
2C2H2 (g) + 5O2 (g) ---> 4CO2 (g) + 2H2O (g)
Commercial
Arc welding electrodes, Satin craft 13, 5 kg, 3.2 mm X 380 mm, pack
Arc welding electrodes, Satin craft 13, 5 kg, 2.5 mm X 300 mm, pack
Arc welding electrodes, GP 6012, 5 kg, 3.2 mm X 380 mm, pack
Arc welding electrodes, GP 6012, 5 kg, 2.5 mm X 300 mm, pack
Arc welding mig wires, automatic, autocraft LWI, 15 kg spool, 0.9 mm
Welding gloves, chrome leather, black and gold
Welding goggles, for oxy-acetylene welding, lift up front
Welding helmet, lift up front, head harness
Welding mats, anti-fatigue, non-slip mats, resistant to welding sparks, 700 mm X 800 mm centre piece
Welding mats, anti-fatigue, non-slip mats, resistant to welding sparks, 700 mm X 800 mm end piece
Welding safety apron, chrome leather, reinforced straps, 910 mm X 560 mm
Wire / scratch brush, four rows of steel bristles with wooden handle
16.1.3.0 Alcohols, phenols, thiols, ethers, epoxy compounds, acetates (ethanoates) benzoyls, acetals
Alcohols are organic compounds with the functional group -OH, but when attached to an aromatic ring called phenols.
Alcohols, alcohols group: (-OH) Suffix: (ol) primary, secondary and tertiary aliphatic alcohols, e.g. Primary alcohol, methanol, CH3OH, Secondary alcohol, propan-2-ol, (CH3)2CHOH, Tertiary alcohol, 2-methylpropan-2-ol, (CH3)3COH
Alcohols, R-OH, are compounds in which a functional group, the hydroxyl group, -OH, is attached to a saturated carbon atom, e.g. R3COH, "hydroxyl" refers to the radical HO-. The "alcohol" in alcoholic beverages is ethanol, ethyl alcohol, CH3CH2OH
See diagram 16.0.1: Tetrahedral geometry of carbon, methane molecule, isobutyl alcohol
Alcohols (ROH), (-ol), alkanols, e.g. methanol (methyl alcohol), (CH3OH), ethanol (ethyl alcohol), (C2H5OH)
16.1.3.1a Ethanol safety
Do not heat ethanol over an open flame but use a water bath. However, ethanol may be use in small quantities in alcohol burners to measure heat of combustion and for reaction with alkanoic acids to form esters.
Ethanol forms violently explosive mixtures with nitric acid and other oxidizing agents.
Ethanol with acidified dichromate solutions is highly exothermic.
Ethanol reacts violently with potassium.
Alcohol flammability, ethanol > 70% (PG II), < 70% (e.g. 24%) (PG III), < 24% not a dangerous good
16.1.3.A Propanol (C3H7OH) has 2 isomers:
1. Propan-1-ol, 1-propanol (n-propyl alcohol), (CH3CH2CH2OH)
2. Propan-2-ol, 2-propanol (iso-propyl alcohol), [CH3CH(OH)CH3]
16.1.3.B Butanol, butyl alcohol (C4H9OH) has 4 isomers:
1. Butan-1-ol, 1-butanol, n-butanol, n-butyl alcohol, (biobutanol), (a primary alcohol), product of carbohydrate fermentation, common flavorant
2. Butan-2-ol, 2-butanol, sec-butanol, sec-butyl alcohol, (a secondary alcohol), product of grain and hops fermentation
3. 2-methylpropan-1-ol, isobutanol, isobutyl alcohol,  IBA, 2-methyl-1-propanol, (CH3)2CHCH2OH, additive to reduce viscosity, flavouring agent
4. 2-methyl-propan-2-ol, tert-Butanol, tert-butyl alcohol, (simplest tertiary alcohol), paint remover solvent
5. 2-butoxyethanol, butyl glycol, butyl cellosolve, C4H9OCH2CH2OH, pH11, in window cleaner "Windex", inks, paint solvents
16.1.3.0.1 Dihydric alcohols, glycol
The dihydric alcohols, glycols, diols, have two hydroxy groups on different carbon atoms, e.g. ethane-1,2-diol, ethylene glycol, glycol (HOCH2CH2OH) butane-1,4-diol [HO(CH2]4OH]
CH2CH2 (oxidation) --> CH2OCH2 (+ water) --> HOCH2CH2OH
ethene (oxidation) --> epoxyethane (+ water) --> ethane-1,2-diol (glycol, antifreeze)
16.1.3.0.2 Trihydric alcohols, glycerol
The trihydric alcohols, have three hydroxy groups on different carbon atoms, e.g. 1,2,3-trihydoxypropane, glycerol [HOCH2CH(OH)CH2OH]
16.1.3.0.3 Nitroglycerine (UK), Nitroglycerin (USA)
glycerol + cold mixture of conc. sulfuric acid + nitric acid --> CH2(NO3)CH(NO3)CH2(NO3), C3H5(ONO2)3, nitroglycerine, ester of nitric acid
Colourless, insoluble oil, solidifies on cooling, contact explosive, used to make dynamite, cordite.
Nitroglycerine is a very unstable liquid that explodes if given a slight shock. It freezes at 13oC but is more likely to explode if solid. It is used to make safer explosives, e.g. dynamite. It is also used in very small tablets for the heart condition angina pectoris where people get out of breath and suffer pain in the chest from over-exertion. 
16.1.3.1.1 Alcohols, primary, secondary and tertiary aliphatic alcohols, rubbing alcohol
Primary alcohols RCH2OH, Secondary alcohols R2CHOH, Tertiary alcohols R3COH
See 3.38: Carbon dioxide and fermentation for brewing
See 16.5.10: Rubbing alcohol, surgical spirit
1. Primary alcohols, e.g. methanol (methyl alcohol, CH3OH), propanol (isomer propan-1-ol, n-propyl alcohol, CH3CH2CH2OH), and butan-1-ol (1-butanol, n-butanol, CH3(CH2)3OH), have two hydrogen atoms attached to the carbon atom attached to the hydroxyl group (-OH). So they all have -CH2OH in their molecules. They can be directly oxidized to aldehydes or carboxylic acids using oxidizing agents.
(O)R1-CH(OH)-R2 --> R1-C(O)-R2(O)R-CH2OH --> R-CHO(O)R-CHO --> R-COOH
2. Secondary alcohols, e.g. propan-2-ol (CH3)2CHOH, rubbing alcohol, isopropyl alcohol and secondary butyl alcohol, butan-2-ol (CH3CH2CH[CH3]OH), [ or CH3CH(OH)C2H5], have one hydrogen atom attached to the carbon atom attached to the hydroxyl group (-OH). So they all have (-CHOH), in their molecules. They can be slowly oxidized to ketones.
(O)R1-CH(OH)-R2 --> R1-C(O)-R2
3. Tertiary alcohols, e.g. 2-methylpropan-2-ol, 2-methyl-2-propanol (CH3)3COH, tertiary butyl alcohol has no hydrogen atom attached to the carbon atom attached to the -OH group. So they all have -COH in their molecules.
4. To one drop of each alcohol in three test-tubes, add saturated potassium manganate (VII) solution drop by drop with shaking. If decolorization occurs, continue adding drops until pink coloration persists as shown by spot testing on filter paper. Add one drop of concentrated sulfuric acid and resume adding potassium manganate (VII) drop by drop. No decolorization occurs with tertiary alcohols. The colour eventually fades with secondary alcohols, but persists with primary alcohols.
16.1.3.1.2 Prepare sodium ethoxide
Sodium ethoxide is the salt of a weak acid, ethanoic acid, and a strong base, sodium hydroxide.
Add a pinhead size piece of sodium to 1 mL of ethyl alcohol. Tests for hydrogen gas:
Na (s) + 2C2H5OH (l) --> 2C2H5ONa (s) + H2 (g)
sodium + ethanol --> sodium ethoxide + hydrogen
Evaporate the sodium ethoxide solution to form white crystals. Add drops of water and tests for litmus that turns blue.
16.1.3.2 Phenols
See diagram 16.1.4.3: Phenols, quinones, naphthols, coniferyl alcohol (p-coumaryl alcohol), urushiol, organohalogens
See diagram 16.1.4.4: Phenols, quinones
See 19.2.1.6: Antioxidant phenols, antioxidants, vitamin E, beta-carotene
See 19.2.1.7: Cholesterol
1. Phenols, Ar-OH, are compounds with an hydroxyl group, -OH, firmly attached to an aromatic ring, e.g. benzene, 2-naphthol, benzene-OH, hydroxybenzenes
Phenols (hydroxyl group -OH), connected to a carbon atom in a benzene ring, benzene-OH, hydroxybenzenes
The -OH is so firmly attached that the O-H bond tends to break to lose an H+ ion to form a weak acid.
2. Phenols divided into mono-, di-, tri- tetra-, and polyhydric phenols.
e.g. p-chlorophenol, C6H4ClOH, 2, 4, 6-tribromophenol, C6H2Br3OH
16.1.3.2a Pyrogallol, C6H3(OH)3, 1,2,3-trihydroxybenzene, white crystals, reducing agent, alkaline solution, (use sodium hydrogen carbonate not sodium hydroxide), reacts with oxygen in the air to form a brown polymer. Pyrogallol is used in experiments where oxygen must be eliminated from a gas or from the air. Pyrogallol is prepared by heating gallic acid, C6H2(OH)3COOH, (3,4,5-trihydroxybenzoic acid).
16.1.3.2.1 Carbolic acid, phenol
Benzene compounds: See diagram 16.8.1
1. Carbolic acid, C6H5OH, "phenol" from coal tar fraction 170oC to 230oC, colourless hygroscopic crystals. Phenol is acidic so ionizes in water:
C6H5OH --> H+ + C6H5O-
Do not wash off with alcohol because carcinogenic products or explosive materials may form. To avoid carcinogenic byproducts, use sulfuric acid, not hydrochloric acid, as a catalyst to prepare polymers.
2. "Phenol", carbolic acid (C6H5OH), is a pale pink crystalline solid, solid because of the hydrogen bonds between the phenol molecules. Pure phenol (carbolic acid) blisters the skin but it is still used in carbolic soaps as an antiseptic. Formerly, it was used as an antiseptic spray in early medical operations. Other antiseptics and disinfectants include TCP (2.4.6-trichlorophenol), and Dettol (4-chloro-3,5-dimethylphenol).
Phenol as a weak acid: phenol + H2O <=> H3O+ + phenoxide ion-
Phenol reacts with alkalis: phenol + NaOH (aq) <=> sodium phenoxide (aq) + H2O (l)
Halogenation of phenol: phenol + bromine --> 2.4.6-tribromophenol
16.1.3.2.2 Naphthols
See diagram 16.1.4.3: Phenols, Quinones, naphthols | See 12.11.5.7: Tests for carbonates, Molisch's test (alpha-naphthol test)
1-naphthol, C10H7OH, a-naphthol, alpha-naphthol, naphthalen-1-ol, tests for carbonates
2-naphthol, C10H7OH, b-naphthol, beta-naphthol, naphthalen-2-ol, white solid, antioxidant in rubber products, antiseptic, tests for primary amines
16.1.3.2.3 Cresols
Cresols, monomethylphenols, epoxy compounds, e.g. 1, 2-epoxypropane, catechol [C6H4(OH)2], pyrocatechol, 1, 2-dihydroxybenzene, 2-hydroxy phenol, urushiol (C6H4(OH)2).
16.1.3.2.4 Resorcinol
See diagram 16.1.4.2: Resorcinol
Resorcinol, 1,3-dihydroxybenzene, benzene-1-3-diol, C6H4(OH)2, dihydroxy phenol, colourless crystals, used for cold-setting adhesives with formaldehyde
16.1.3.2.5 Triclosan, organohalogens
See diagram 16.1.4.2: Triclosan
Triclosan, 5-chloro-2-(2,4-dichlorophenoxy) phenol, C12H7Cl3O2, is an organohalogen polychlorophenoxy phenol used in anti-bacterial and anti-fungal products, and in low concentrations in many other products, including toothpaste, mouthwash, deodorants, soap, scent, detergent dishwashing liquid, at high concentrations is Harmful by inhalation, irritant, environmental danger, and is suspected of causing bacterial resistance because of it widespread use and occurrence in the environment and may weaken the immune system. Other organohalogens include:
2, 4, 6-trichlorophenol, 2, 4, 6-tribromianisole, 2, 4, 6-trichloroanisole
chlorophenol compounds + filamentous fungi --> 2, 4, 6-trichloroanisole
16.1.3.3 Thiols
See diagram 16.1.4.3: Thiophenol (phenyl mercaptan), | See diagram 16.13.10: Metam, zineb
Thiols, thio-alcohols (RSH, R not equal to H), (sulfhydryl group: -SH, characteristic of thiols), (Suffix: -thiol), [old name: mercaptans, because react with mercuric ion to produce mercaptides (RS)2Hg], e.g. methanethiol, methyl mercaptan (CH3SH), ethanethiol (MeCH2SH), ethyl mercaptan (ethanethiol or ethan-ethiol or captan), (C2H5SH), 1-butanethiol, n-butyl-mercaptan (CH3CH2CH2CH2SH), thiophenol, phenyl mercaptan Ph-SH, sodium thiolate: (RS-Na+), thiols, RS-H, are oxidized to disulfides, RS-SR
Methanethiol from asparagus
The methylmethionine and asparagusic acid, alpha-aminodimethyl-gamma-butyrothetin, in asparagus may produce methanethiol, dimethyl disulfide and dimethyl sulfone in people who eat asparagus. However, less than 50% of adults can smell these compounds in the urine.
16.1.3.4 Ethers
Two hydrocarbon groups linked by one oxygen, compounds in the form: R1OR2 (R not equal to H), where R1 may or may not be the same as R2, e.g. the anaesthetic diethyl ether. Ethers (ROR'), (CnH2n+2O), alkyl ethers, ethoxethane ether, e.g. dimethyl ether (CH3OCH3), diethyl ether, ether anaesthetic (C2H5OC2H5, CH3CH2OCH2CH3).
16.1.3.6 Acetates (ethanoates), ROAc, salt or ester of ethanoic acid (acetic acid)
As a salt: sodium acetate, sodium ethanoate (CH3COONa). As an ester: ethyl ethanoate (CH3COOC2H5)
16.1.3.7 Benzoyl group, benzene carbonyl group C6H5CO-
e.g. benzoyl chloride (C6H5COCl)
16.1.3.8 Acetals (alcohol + aldehyde), RCH(OR')2
Acetal, 1,1-diethoxy ethane [CH3CH(OC2H5)2], smelly liquid, formed by reaction of acetaldehyde with ethanol
Hemiacetals: [RCH(OH)R'], Di-methyl acetals: [RC(OMe)2R'], Di-ethyl acetals: [RC(OEt)2R']
(polyacetals, polyoxymethylene resin POM)
16.1.5.3 Salts, e.g. sodium ethanoate (sodium acetate) (CH3COONa), ammonium acetate (CH3COONH4)
NaHCO3 + CH3COOH --> CH3COONa  + H2O + CO2 (g)
16.1.5.5 Acyl halide, acid chloride, Acid chlorides group: (-COCL), Suffix: -oyl chloride
acyl chloride (RCOCl), e.g. ethanoyl chloride (acetyl chloride), (CH3COCl)
16.1.5.6 Amides, acid amides (-amide), (amide group: -CONH2, RCONH2)
See diagram 16.13.7: Carbamates, carbaryl, methiocarb
See diagram 16.13.8: Deet, DMP dimethylphthalate
e.g. urea (H2NC=ONH2), [IUPAC: Do NOT distinguish amides with NH2, NHR, NR2 groups by the terms "primary, secondary, tertiary".]
(primary amides RCONH2), e.g. alkanamides: ethanamide (acetamide), (CH3CONH2) propanamide (C2H5CONH2)
(secondary amides, N-substituted amides RCONHR')
(tertiary amides RCNR'R"), secondary or tertiary amides have the prefix N, e.g. N-ethylethanamide CH3CONHCH2CH3, N.N-dimethylmethanamide HCON(CH3)2 (the polymer group -CO-NH-), (inorganic amides, e.g. KNH2)
carbamates: esters of carbamic acid [H2NC(=O)OH], methiocarb, urethanes [R2NC(=O)OR', where R' not = H, R= ethyl], e.g. polyurethane resins, cyanides, imidesisocyanates, quinines, carbamide (urea), [CO(NH2)2], carbazole C12H9N, Deet
16.1.5.6.01 Physostigmine
From Calabar bean, (Physostigma venenosum), alkaloid C15H21N3O2, poison bean but used in pharmacy as ant-CNS depression, antidote for belladonna poisoning, cholinesterase inhibitor
16.1.5.6.1 Acrylamide, 2-Propenamide, ethylene carboxamide, acrylic amide, vinyl amide
Acrylamide, CH2CHCONH2, is the amide of acrylic acid, propenoic acid, (CH2CHCOOH), an unsaturated liquid carboxylic acid. It is a poison, harmful if swallowed, inhaled or absorbed through skin, affects central and peripheral nervous systems and reproductive system, causes irritation to skin, eyes and respiratory tract, suspected cancer hazard depending on level and duration of exposure, possible birth defect hazard, thermally unstable, can polymerize explosively if heated to the melting point, most common in overcooked french fries and potato chips, also burned toast and burned high carbohydrate foods.
16.1.5.7 Acid anhydrides, acyl anhydrides, anhydrides [RCO-O-COR' (R(C=O)O(C=O)R')]
e.g. ethanoic anhydride (acetic anhydride), [(CH3CO)2O], ethanoic anhydride [CH3(C=O)O(C=O)CH3], trifluoroethanoic propanoic anhydride [CH3CH2(C=O)O(C=O)CF3]
16.1.5.8 Imides (R1CO-NH-COR2), (imido group: -CONHCO-), e.g. glutemide (C13H15NO2), the polymer group (-CO-NR-CO), polyimides, N-(trichloromethylthio), cyclohex-4-ene-1, 2-dicarboyimide
16.1.12 Fractional distillation of crude oil
A fractionating column is used to separate the distillates that boil within a temperature range, i.e. the fractions.
Fractional distillation of crude oil: petroleum gas (LPG), naphtha, petrol (gasoline), kerosene (paraffin oil), diesel oil, lubricating oil (motor oil), paraffin wax (fuel oil), residuals (bitumen, "tar", asphalt, waxes)
The word "asphalt" can refer to natural bituminous pitch, e.g. the Trinidad Pitch Lake, or the fraction of crude oil produced by distillation or the "hot mix" mixture of aggregate and bitumen used to surface roads, paths and school playgrounds.
16.1.12.1 Petroleum gas (methane, ethane, propane, butane)
Mix of 1 to 4 carbon atoms, boiling range < 40oC. Liquefied under pressure as LPG (liquefied petroleum gas), a mixture mainly of propane (C3H8), and butane (C4H10).
16.1.12.2 Naphtha (petroleum naphtha, ligroin), processed to make gasoline
Mix of 5 to 9 carbon atoms, mainly aliphatic, e.g. alkanes, boiling range 120oC to 180oC, or < 200oC. The light hydrocarbon cut between gasoline and kerosene. (Another naphtha can also be produced from coal tar.)
16.1.12.3 Petrol, "gas", gasoline, motor fuel
Mix of C6H14 to C11H24, 5 to 12 carbon atoms, alkanes and cycloalkanes, boiling range 40 to 205oC
16.1.12.4 Kerosene, kerosine, paraffin oil, jet engine fuel, tractor fuel
Mix of C12H26 to C15H32, 10 to 18 carbon atoms, alkanes and aromatics, boiling range 175oC to 325oC
16.1.12.5 Diesel oil, gas oil or diesel distillate, diesel fuel, heating oil
Mix of C15H32 to C18H38, 12 or more carbon atoms, alkanes, boiling range 250oC to 350oC
16.1.12.6 Lubricating oil, motor oil, grease
Mix of C16H34 to C24H50, 20 to 50 carbon atoms, alkanes and cycloalkanes and aromatics, boiling range 300oC to 370oC
16.1.12.7 Paraffin wax, heavy gas, fuel oil, Mix of C20H42 and higher hydrocarbons, 20 to 70 carbon atoms, alkanes and cycloalkanes and aromatics, boiling range 370oC to 600oC
16.1.12.8 Residuals, bitumen, "tar", asphalt, waxes
A mix of C24H50 and higher hydrocarbons, multiple-ringed compounds, 70 or more carbon atoms, boiling range > 600oC
Petroleum jelly is a saturated semi-solid of crystalline and liquid hydrocarbons, carbon numbers < C25, made by dewaxing paraffinic residual oil.
naphtha, "Greek fire", was an inflammable bituminous substance used in warfare.
16.1.13 Prepare triodomethane (iodoform)
See 1.6: Iodine solution | See diagram 16.2.2: Halogen compounds, haloalkanes
Add five drops of iodine solution to five drops of ethanol. Add drops of dilute sodium hydroxide solution until the brown colour of iodine disappears. Observe the crystals under a microscope.
C2H5OH + 4I2 + 6NaOH --> HCOONa + 5NaI + 5H2O + CHI3
ethanol + iodine + sodium hydroxide --> sodium methanoate (sodium formate) + sodium iodide + water + triodomethane (iodoform)
16.1.14 Prepare trichloromethane (chloroform)
See diagram 16.1.7: Prepare chloroform | See 16.2.2: Chlorinated hydrocarbons, haloalkanes
Bleaching powder is usually a mixture of calcium chlorate (I) [basic calcium chloride, calcium hypochlorite], calcium chloride and calcium hydroxide prepared by passing chlorine gas through a calcium hydroxide solution. Calcium chlorate (I) oxidizes ethanol to ethyl aldehyde. Aldehydes or ketones have a hydrogen atom attached to the carbon atom attached to the carbonyl group, C=O.
This hydrogen atom can be replaced by a halogen atom to form halogen compounds. If a molecule contains three such hydrogen atoms, e.g. ethanol and propanone (acetone) molecule, a trihalide may be formed, e.g. trichloromethane (chloroform, CCl3).
H3C-C(O)-R + 3OX --> X3C-C(O)-R
ketone or aldehyde hypochlorite --> trihalide
The trihalide decomposes in a basic solution to a haloform (CHX3), e.g.:
CHCl3C-C(O)-R (l) + OH- (aq) --> CHCl3 (l) + RCOO- (aq)
Reactions of ethyl alcohol with bleaching powder
C2H5OH (l) + Cl2 (g) --> CH3CHO (l) + 2HCl (aq)
ethyl alcohol + chlorine --> ethyl aldehyde
CH3CHO (l) + 3Cl2 (g) --> CCl3CHO (l) + 3HCl (aq)
2CCl3CHO (l) + Ca(OH)2 (aq) --> 2CHCl3 (l) + (HCOO)2Ca (aq)
Decomposes trichloromethane to calcium formate
Ca(OH)2 (aq) + 2HCl (aq) --> CaCl2 (aq) + 2H2O (l)
Reactions of acetone with bleaching powder
CH3COCH3 + 3Cl2 --> CCl3COCH3 + 3HCl
2CCl3COCH3 + Ca(OH)2 --> 2CHCl3 + (CH3COO)2Ca
Ca(OH)2 + 2HCl --> CaCl2 + 2H2O
Be careful! Do not allow any flames in the laboratory!
Grind together in a mortar and pestle 5 g bleaching powder and 10 mL water. Put the mixture into the test-tube of the gas preparation apparatus. Cool the test-tube. Add either 4 mL ethanol in 2 mL water or 4 mL propanone (acetone) in 2 mL of water. Swirl the contents of the test-tube and keep it cool. Use an electric water bath to warm the temperature to 55oC. Water and trichloromethane condense in the receiving test-tube leaving a calcium salt solution in the test-tube. Add water to the distillate and separate the trichloromethane with a separating funnel.
16.2.2 Halogen compounds, haloalkanes (alkyl halides), halogen derivatives
Acyl halides, (acid halides; RCOX, where X = halide group and R = organic group, e.g. acetyl = CH3CO-)
Haloforms, e.g. trihalomethanes CHX3
Alkanes react with chlorine and bromine in ultraviolet light to produce haloalkanes, e.g. 2-chloropropane.
See diagram 16.2.2: Chlorinated hydrocarbons, methyl chloride, methylene chloride, chloroform, carbon tetrachloride
See diagram: 16.13.5: Bifenox, dicofol, naled, trichlorophon, tetrachlorvinphos
See diagram 16.13.11: MCPA, 2, 4-D, 2, 4, 5-T, picloram
1.0 Chlorine: acyl chlorides, acid chlorides (acyl = RC=O-), ethanoyls (-COCl), (-oyl chloride), ethanoyl chloride (acetyl chloride), (CH3COCl), chloroform CHCl3, chloromethane (methyl chloride), (CH3Cl), ethylene dichloride (1,2-dichloroethane, Freon 150), (ClH2C-CH2Cl), chloroethene (vinyl chloride) (CH2:CHCl), tetrachloromethane (carbon tetrachloride), (CCl4), phosgene (carbonyl dichloride), COCl2, chlorine + sulfur: thiophosgene (thiocarbonyl dichloride), (CSCl2), chlorine + OH: dicofol, MCPA, 2, 4-D, 2, 4, 5-T, chlorine + N: Bifenox, chlorine + P: trichlorophon, tetrachlorvinphos
2.0 Iodine: iodoform (tri-iodomethane), (CHI3), iodoethane (CH3CH2I)
3.0 Bromine: bromoform (CHBr3), ethyl bromide (bromoethane), (C2H5Br), ethylene dibromide (1:2-dibromoethane), Halons (fire extinguishers): Halon-1211 bromochlorodifluoromethane (CBrClF2), Halon-1301 bromotrifluoromethane (CBrF3)
4.0 Fluorine: fluoroform (CHF3), tetrafluoroethene (CF2CF2), polytetrafluoroethene (PTFE, Teflon), (-[CF2-CF2]x-)
5.0 Magnesium with PTFE, polytetrafluoroethylene, aircraft flares, heat-seeking missile decoys
2n Mg + (C2F4)n --> 2n MgF2(s) + 2n C(s)
6.0 Chlorofluorocarbons, CFCs (old name = Freons): CFC-11 trichlorofluoromethane (CCl3F), CFC-12 dichlorodifluoromethane (CCl2F2)
See "Freons": 12.19.5.1
16.2.3 Organometal compounds (prefixing the metal with organo-), e.g. organomagnesium compounds, MeMgI iodo(methyl)magnesium, Et2Mg diethylmagnesium
16.2.3.1 Carbides (C4-), (carbon + metal), e.g. chromium carbide, Cr3C2, iron carbide Fe3C (cementite), silicon carbide SiC,  calcium dicarbide, (calcium carbide, carbide, calcium acetylide, ethnide), (CaC2), tungsten carbide ("carbide", WC)
Methanides + water --> methane, e.g.  aluminium carbide, (Al4C3)
Acetylides (percarbides, C22-) + water --> acetylene, e.g. Na2C2, CaC2
Sesquicarbides, e.g. Mg2C3
Iron carbide is formed with carbon monoxide when iron oxide is heated with charcoal.
3Fe2O3 +11C --> 2Fe3C + 9CO (g)
16.2.4 Nitrogen compounds, one atom of nitrogen
See 16.1.5.6: Amides
16.2.4.2 Nitriles (acid nitriles, alkyl cyanides, cyanides), (-CN, RC=-N), (cyanide ion: CN-), e.g. ethane nitrile (methyl cyanide, ascetonitrile) (CH3C=--N), 5-methoxyhexanenitrile, [CH3C(OCH3)HCH2CH2CH2C=--N], acrylonitrile for making Orlon (vinyl cyanide, 1-cyanoethene), (CH2=CH-C=-N)
16.2.4.2.1 Cyanamides, (inorganic, CN22-), ionization reaction of methylamine
See diagram 16.2.4.2.1: Melamine
cyanic acid (fulminic acid), (HOC =-N), (cyanates, fulminates), Isocyanic acid (H-N=C=O), isocyanates (isocyanate group: -NCO, HN=C=O), isocyanides (HN=--C), hydrocyanic acid (HC=-N)
CaCn2 + H2O + CO2 --> H2NCN + CaCO3
calcium cyanamide + water + carbon dioxide --> cyanamide + calcium carbonate
(NH2)2CO --> HCNO + NH3
urea --> cyanic acid + ammonia
6HCNO --> C3H6N6 + 3CO2 (polymerization reaction)
cyanic acid --> melamine + carbon dioxide
6(NH2)CO --> C3H6N6 + 6NH3 + 3CO2
Melamine, 1, 3, 5-triazine-2, 4, 6-triamine, is 66% nitrogen w/w and is used in the plastics industry. Unfortunately, its high nitrogen content has been the reason for its use as a powdered milk pollutant in China resulting in death and kidney problems in young babies due to the formation of kidney stones.
Commercial
Melamine crockery, green, virtually unbreakable, dishwasher safe, Not suitable for microwave oven, plate, 18 mm diameter
16.2.4.3 Amines, aliphatic amines (RNH2-, R = alkyl group), ionization reaction of methylamine
Primary amines: RNH2, NH2- = amino group, e.g. mono-methylamine methylamine (CH3NH2), ethylamine (CH3CH2NH2)
Secondary amines: R2NH, NH = imino group, e.g. di-methylamine didimethyl amine [(CH3)2NH], diethylamine
Tertiary amines: R3N, trimethylamine [(CH3)3N], triethylamine, methylamine hydrochloride
Ionization reaction of methylamine
CH3NH2 + H2O <--> CH3NH3+ + OH-
Nitrosamines, produced by nitrous acid with secondary amines, can be formed in the gut when nitrites react with amino acids.
16.2.4.3.1 Ethylenediamine
ClCH2CH2Cl + 4 NH3 --> H2NCH2CH2NH2 + 2 NH4Cl
1,2-dichloroethane + ammonia --> ethylenediamine + ammonium chloride
16.2.4.3a Imines
Imino group = ring containing (-NH-), or (=NH), linked to C], (RN=CR', where R = H or hydrocarbyl, e.g. (ethyl-), 0-benzoquinonedimine
Imine primary RC(=NH)R’ (imino-), (-imine)
Imine secondary RCH=NR’ (imino-), (-imine)
16.2.4.4 Nitroalkanes (nitroparaffins), (CnH2n+1NO2)
Nitromethane (CH3NO2), nitroethane, urea (carbamide)
16.2.4.5 Nitrites (NO2-), dioxonitrate ion, salts or esters of nitrous acid (O=NOH), e.g. sodium nitrite and potassium nitrite as meat curing agents
16.2.4.6 Oximes (hydrox-imino-alkanes)
Formula R1R2C=NOH, where R1= organic side chain and if R2 = hydrogen, aldoxime forms  or if R2 = organic group, ketoxime forms.
(-CNOH group), (ketone or aldehyde + hydroxylamine - water), (RCNOHR'), e.g. ethanal oxime (acetaldehyde oxime, AAO), (CH3CH=NOH)
16.2.4.7 Cyanocrylates [(CH2)C(CN)COOR]
e.g. "Superglue": Me or Et ester
16.2.5 Nitrogen compounds, two or more nitrogen atoms
16.2.5.1 Azide
Azide compounds: (N3-), or (-N3), (-N=N+N-), usually attached to carbon, e.g. sodium azide (NaN3), phenyl azide or azidobenzene (PhN3), diazine (diimide), (HN=NH), also, salts of hydrazoic acid, HN3. e.g. sodium azide (NaN3).
16.2.5.2 Azo
 Azo compounds: derivatives of diazene (diimide), HN=NH, with both hydrogens substituted by hydrocarbyl groups, e.g. azobenzene or diphenyldiazene (PhN=NPh).
hydrazone (ketone + hydrazine (N2H4) - water), (RC=NNH2R')
16.2.5.3 Diazo
 Diazo compounds: (RN=NR'), e.g. diazomethane (CH2=N2), diazonium compounds [(RN =- N+) Cl-]
benzenediazonium chloride + phenol --> 4-(phenylazo)phenol + NaCl
benzene-N+=-NCl- + H-benzene-OH + NaOH --> benzene-N=N-Benzene-OH +NaCl + H2O
4-(phenylazo)phenol is a yellow dye
Azo dyes of the textile industry use diazonium salts. The material is first soaked in a soluble salt of phenol or naphthol then soaked in a diazonium salt so that the dye forms in the cloth.
16.2.5.4 Phenylhydrozone
Phenylhydrozone [RC=N(NH), (Phenyl group) R'], (ketone or aldehyde + phenylhydrazine, [C6H5(NH)NH2] - water), 2, 4-dinitrophenylhydrozone, semicarbazone [RC=N(NH)CO(NH2)R']
16.2.6 Phosphorous compounds, organophosphorus insecticides
Organophosphorus insecticides (mostly thiophosphates), TEPP (tetraethylpyrophosphate, no longer used as insecticide), parathion, maldison (Malathion), dimethoate (Rogor), dichlorvos (dimethyl dichlorovinyl phosphate, DDVP, Shelltox strips), demetron (Systox),
Organophosphates, acephate, dichlorvos, dimethoate, malathion (maldison), parathion
See diagram 16.13.6: Benomyl, captan, glyphosate, paraquat
1. Phosphonic acid, orthophosphorous acid [HP(=O)(OH2) H3PO3]
2. Phosphonoglycine, N-(phosphonomethyl) glycine, glyphosate (in "Roundup" weedicide), (C3H8NO5P)
3. Organic phosphates: acephate, diazinon, dichlorvos, dimethoate, malathion (maldison) naled, parathion
16.2.8 Sulfur compounds, For the "thio" prefix, replace oxygen by sulfur, e.g. thiobenzamide [PhC(=S)NH2]
16.2.8.1 Isothiocyanates (old name: mustard oil), (RN=C=S), mustards [X(CH2.CH2)2S]
16.2.8.2 Sulfides: RSR (R not equal to H), (old name: thioethers), e.g. diallyl sulfide (garlic smell), [CH2=CHCH2)2S], or inorganic salts of hydrogen sulfide. Most people who eat asparagus notice a smell, the over-boiled cabbage smell, in their urine because of sulfur compounds, e.g. dimethyl sulfide, dimethylsulfone, sulfimides (sulfilimines): (H2S=NH)
16.2.8.3 Sulfonic acids, [HS(=O)2OH]
16.2.8.4 Sulfonium compounds: R3S+, e.g. trimethylsulfonium chloride {[(CH3)3S]+Cl-}
16.2.8.5 Thiocyanates: [RC(=O)SN] salts and esters of thiocyanic acid HSCN, e.g. methyl thiocyanate (CH3SC =- N)
16.2.8.6 Silicones: polymeric unbranched siloxanes, formula (-OSiR2-)n (R not equal to H)
16.2.8.7 Siloxanes
Saturated silicon-oxygen hydrides with chains of alternating silicon and oxygen atoms, e.g. unbranched [H3Si(OSiH2)nOSiH3], branched [H3Si(OSiH2)nOSiH(OSiH2OSiH3)2]. "Volasil" is octamethylcyclotetrasiloxane. Dimethylpolysiloxane is an anti-caking agent, emulsifier and anti-foaming agent.
16.2.8.8 Thiols, thio-alcohols See 16.1.3.3
16.2.8.9 Sulfoxide, dimethyl sulfoxide, (DMSO (CH3)2SO), (C2H6OS)
propanethial S-oxide, C3H6OS, lachrymatory factor from cut onion cells, Allium cepa, formed when enzyme allinase reacts wit S-1-propenyl-L-cysteine sulfoxide
16.2.10 Coal tar products, creosote
Chemicals produced from destructive distillation of coal when making coke for steel production. Many organic compounds can be isolated by distillation of coal tar but many are now made from petroleum or natural gas. The residue of coal tar distillation is called pitch and is used for road tar and waterproofing of roof material. The residue of petroleum distillation is called asphalt but also called "tar". Coal tar paints resist heat and moisture. Coal tar dyes, called azo dyes, are made from azobenzene and were used as food colourings.
Coal tar products include:
1. hydrocarbon oils, e.g. benzene, toluene, xylene
2. phenols, e.g. carbolic acid, and
3. bases. e.g. pyridine.
Coal tar is a creosol mixture that includes  2-hydroxytoluene, 3-hydroxytoluene, 4-hydroxytoluene. It sensitizes skin to sunlight, so use gloves because it may cause skin cancer. It is used as a  wood preservative of railway sleepers, telegraph poles., fungicide, soap for treatment of skin diseases, and sheep dip  insecticide.
However, wood creosote is a mixture of phenols of wood tar and is used as a disinfectant, cough medicine, diarrhoea medicine, preservative, and antiseptic.
16.3.1 Prepare ethanal (acetaldehyde) with potassium dichromate
Add two drops of 0.1 M potassium dichromate solution to two drops of ethanol and ten drops of dilute sulfuric acid. Heat gently. The orange potassium dichromate solution turns green showing the presence of Cr3+. The reaction forms ethanal then ethanoic acid (acetic acid). Note the odour of an acetaldehyde.
C2H5OH + (O) --> CH3CHO + H2O
ethanol + (oxygen) --> ethanal + water
CH3CHO + (O) --> CH3COOH
ethanal + (oxygen) --> ethanoic acid
K2Cr2O7 + 4H2SO4 + 3CH3CH2OH --> K2SO4 + Cr2(SO4)3 + 7H2O + 3CH3CHO
16.3.1a Aldehydes, alkanals (aliphatic aldehydes), ketones, quinones
Aldehydes (-CHO), (-al) alkanals, e.g. methanal (formaldehyde), (CH2=O, HCHO), ethanal (acetaldehyde), (CH3CHO)
Aldehydes are compounds in the form RC(=O)H, where a carbonyl group is bonded to one hydrogen atom and to one R group. Aldehydes contain the aldehyde group (-CHO), which is a carbonyl group (C=O), with a hydrogen atom attached to the carbon atom. Methanal (HCOH, formaldehyde), and ethanal (CH3CHO, acetaldehyde), are the simplest aldehydes (RCHO, alkanals). Aldehyde names end with "-al". Aldehydes are reducing agents and can be detected with Tollens' test or Fehling's test. Most monosaccharides and disaccharides can act as reducing agents, but not sucrose, and can be detected by Fehling's test or Benedict's test.
16.3.5.1 Aesculin (escalin)
It is a glucoside from the horse chestnut Aesculus hippocastanum. It is used to identify Enterococcus bacteria. It gives pale blue colour by reflected light and straw colour by transmitted light.
16.3.5.2 Amido phthalic acid and amido-tarephthalic acid
It gives pale violet colour by reflected light and pale yellow colour by transmitted light. Amido-tarephthalic acid gives bright green colour by reflected light and pale green colour by transmitted light.
16.3.5.3 Eosin (eosine)
Eosin, bromoeosin, gives yellow green colour by reflected light and orange colour by transmitted light. It is formed by reaction of bromine with fluorescein, the potassium salt of tetrabromo-fluorescein, sodium-2,4,5,7-tetrabromofluorescein, C20H6Br4O5K2. “Eosin Y” has yellowish colour, and “eosin B” (Acid red), has bluish colour. It is used as a counter stain to haematoxylin for microscopic examination. Eosin, an acidic dye, stains cytoplasm stained orange-pink and haematoxylin, a basic dye, stains nuclei blue or purple where nucleic acids mainly occur. Eosin stains red blood cells intensely red.
16.3.5.4 Fluorescein
See diagram 16.3.1.1: Fluorescein
It gives intense green colour by reflected light and orange yellow colour by transmitted light. It is 1, 3-dihydoxybenzene phthalein, [2-(6-hydroxy-3-oxo-xanthen-9-yl), benzoic acid], C20H12O5, red crystals that can dissolve in alkali to form a red colour and green fluorescence.
16.3.5.5 Fraxin
It gives blue-green colour by reflected light and pale green colour by transmitted light. It is a colourless glucoside found in the bark of the ash tree, Fraxinus. Fraxin and esculin are two coumarins found in Actinidia chinensis and Actinidia deliciosa (kiwi fruit, Chinese gooseberries).
16.3.5.6 Magdala red
It gives opaque scarlet colour by reflected light and brilliant carmine colour by transmitted light.
16.3.5.7 Quinine
Quinine, C20H25N2O2, gives a pale blue colour by reflected light and no colour by transmitted light. It is an alkaloid from the bark of Cinchona and Remijia in South America. It was formerly an anti-malarial medicine and is still used for treatment of some heart conditions. As a medicine it was taken in carbonated mineral water but nowadays is still taken as a beverage called "tonic water" which is valued for its slightly bitter taste. Tonic water is not a medicine. Fluorescence spectroscopy can be used to determine the percentage quinine content in commercial samples of tonic water or bitter lemon. by comparing the fluorescence of a sample in ultraviolet light to the fluorescence of a standard quinine sulfate solution containing 10 mg of quinine sulfate in 1L of deionized water.
16.3.5.8 Safranin (safranine, safranin O, basic red 2)
It gives yellow red colour by reflected light and crimson colour by transmitted light. It is a biological stain colouring all cell nuclei red. It is used as a counterstain in a Gram stain in microbiology. It can also be used for the detection of cartilage and mucin and as a redox indicator in analytical chemistry. Safranines are the azonium compounds of symmetrical 2, 8-dimethyl-3, 7-diamino-phenazine.
16.3.2 Prepare ethanal with potassium manganate (VII) [potassium permanganate, Condy's crystals]
Add one drop of 1% potassium manganate (VII) to five drops of ethanol and ten drops of dilute sulfuric acid. Heat gently. The purple colour disappears as potassium manganate (VII) solution is reduced to manganese (II) sulfate. Note the odour of an acetaldehyde.
CH3CH2OH + (O) --> CH3CHO + H2O
2KMnO4 + 3H2SO4 + 5CH3CH2OH --> K2SO4 + 2MnSO4 + 8H2O + 5CH3CHO
16.3.3 Oxidation of methanol to methanal using a platinum catalyst
See diagram 16.3.3: Oxidation of methanol
Be careful! This experiment may be too dangerous for your school. Test the experiment in the science preparation room before demonstrating it in the classroom. Do not let anyone look down into the flask if the experiment appears not to be working!
Put 10 mL methanol in a flask and heat briefly with a Bunsen burner. Heat a piece of platinum wire connected to a copper wire until it is red-hot. Hook a copper / platinum wire inside the flask to start the reaction. You can reheat the wire if the reaction does not start. The reaction continues till all the MeOH is used up. To stop the reaction, remove the catalyst platinum wire catalyst. Be careful!
The methanol is oxidized to methanal when the vapour reaches a certain concentration accompanied by a loud "whoosh" sound as the vapour burn and leaves the flask. The copper T-piece acts as a chimney allowing entry of air when the vapour bums. The Pt wire changes from red-hot to silver.
CH3OH + ˝ O2 --> CH2O + H2 (Pt catalyst)
CH2O + O2 --> CO2 + H2O (Pt catalyst)
16.3.8 Ketones (=CO), (-one), e.g. propanone (acetone), (CH3C=OCH3)
Ketones have a carbonyl group (C=O), bonded to two carbon atoms in the form R2C=O, but neither R may be H. Ketones contain the ketone group (-CO-). It is a carbonyl group with two single bonds to other carbon atoms. Propanone (acetone, CH3COCH3), and butanone (CH3COC2H5, methyl ethyl ketone), are the simplest saturated ketones (R1COR2). Ketone names end with "-one". Ketones cannot be detected with Tollens' test or Fehling's test.
Muscone, C16H3O, methylcyclopentadecanone, is the perfume fixative musk from musk deer but is now produced artificially.
16.3.9 Diacetyl, 2,3-butanedione
Diacetyl, CH3COCOCH3, is used in the popcorn industry to give a butter or butterscotch flavour to popcorn sold in bags. However, workers in the popcorn industry have reported medical problems with their respiratory systems, particularly the lungs, leading to workers compensation. If you heat bags of popcorn in a microwave oven similar problems may occur. The popcorn industry is considering not using diacetyl in bagged products.
16.3.10.0 Quinones
See diagram 16.1.4.3: Quinones
See 16.3.5.0: Polycyclic aromatics
(Contains C=O group in unsaturated ring,
C=O groups in an unsaturated ring, as 1,2-quinones and 1, 4-quinones, (e.g. cyclohexandiene-1,4-dione), cyclic dione structure, conjugated diketones, e.g. benzoquinone, by conversion of -CH= groups into -C(=O)- groups, "quinone": cyclohexadiene-1,4-dione, 1, 4-benzoquinone is the simplest quinone, C6H4O2, all are coloured, many are plant pigments, e.g. lawsone from Lawsonia inermis the orange dye henna, and juglone from walnut shells, Juglans regia, formed from oxidation of hydroquinone and in pecan nuts, and are used in dyes, hydroquinone, 1,4-dihydroxybenzene, used in photography developer, also coenzymes Q in animal and plant cells and plastoquinones involved in photosynthesis, also vitamin K. Juglone, C10H6O3, is produced by some trees in the walnut family, e.g. black walnut, Persian walnut, butternut, and pecan and is leached or released into the soil. Juglone has fungicide and insecticide properties but it is toxic to many plant species.
16.3.10.1 Pindone
See 16.3.5.1: Pindone, sodium salt
Pindone, (ISO 1750), (2-pivaloylindan-1,3-dione), C14H13O3, is an anticoagulant drug used to control rodents and rabbits, e.g. "Bunnybait" is 0.5 g /kg sodium salt of pindone is used as an oat bait for rabbits, C14H13NaO3.