School Science Lessons
Topic 16 Organic chemistry, tests for organic compounds
2013-06-11
Please send comments to: J.Elfick@uq.edu.au
See: IUPAC, Nomenclature of Organic Chemistry (website)
Table of contents
16.1.0 Organic chemistry
16.1.3.8 Acetal, (alcohol + aldehyde), RCH(OR')2
16.1.3.6 Acetates, (ethanoates), ROAc
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
16.1.1.0 Acyclic hydrocarbons, alkanes, alkenes, alkynes, (List)
16.1.01 Addition reactions
16.1.3.0 Alcohols, phenols, thiols, (List)
3.8.0 Alcohols, Fatty alcohols
16.1.3.1a Alcohol, Ethanol safety
16.3.2.0 Aldehydes, ketones, quinones, (List)
16.3.6.4 Alkaloids from plants
16.1.1.1.0 Alkanes, (CnH2n+2), paraffins
16.1.1.1e Tests for unsaturated alkanes
16.1.1.2.0 Alkenes, (CnH2n), olefins
16.1.1.3.0 Alkynes, (CnH2n-2), acetylenes
16.1.5.6 Amides, acid amides group: (-CONH2, RCONH2), Suffix: -amide
16.2.4.3.00 Amines, aliphatic amines, (RNH2-), R = alkyl group, ionization reaction of methylamine
16.1.1.1b Arenes, benzene
16.1.3.7 Benzoyl group, benzene carbonyl group: (C6H5CO-)
Carbamates
16.2.3.1 Carbides (C4-), (carbon + metal)
16.3.8.0 Carboxylic acids and fatty acids, (List)
16.4.1.01 Carbonyls
16.2.4.3.2 Chloramines in swimming pools
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
16.3.6.1 Essential oils, volatile oils, ethereal oils
16.5.0 Esters, derivatives of fatty acids, (List)
16.1.1b Ethane, (C2H6), prepare ethane
16.1.3.4 Ethers, group: (-O-), in organic compound
Diethyl ether, C2H5OC2H5, (C2H5)2O, anaesthetic "ether", ethoxyethane
16.1.3.5 Ethyl cellulose
3.4.3.1 Epoxy compounds, (O atoms in CCO ring), Epoxy resin polymers, thermoset plastics
16.2.4.3.1 Ethylenediamine
16.3.6.2 Fixed oils
16.3.5.0 Fluorescent liquids, (List)
16.2.2 Halogen compounds, haloalkanes, (alkyl halides), halogen derivatives
1.0 Chlorine
16.14.0 Dioxins, Agent orange, polyvinyl chloride
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
12.19.5.2 Methyl bromide, bromoethane, CH3Br
16.2.4.3.01 Methylamine ionization reaction
16.2.4.3.03 Nitrosamines
16.2.4.3.04 Nitramine, (acid-base indicator)
16.2.4.2 Nitriles (acid nitriles, alkyl cyanides, cyanides), (-CN, RC≡N), (note triple bond), 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
16.2.5.0 Nitrogen compounds, two or more nitrogen atoms, (List)
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
16.1.5.6.01 Physostigmine
3.32.0 Prepare gases with a gas generation apparatus
16.1.00 Prepare organic compounds, addition, oxidation, reduction, substitution (displacement)reactions
16.2.4.3.02 Prepare phenylamine
16.3.10.0 Quinones
16.1.5.3 Salts, organic salts, e.g. sodium ethanoate, (sodium acetate, CH3COONa), (ammonium acetate, CH3COONH4)
16.1.5.4 Saturated hydrocarbons, e.g. hexane, C6H14
16.2.8 Sulfur compounds, (List)
16.4.5.0 Tests for organic compounds, (List)
16.3.6.3 Vegetable oils, Plant oils, vegetable oils, (List)
16.1.1 Acyclic hydrocarbons
16.1.1.0 Acyclic hydrocarbons, alkanes, alkenes, alkynes
16.1.1.01 Formation of alkanes
16.1.1.1.0 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
3.39.1 Methane with steam
Natural gas
Natural gas (Methane)
16.1.1h Octane, (C8H18), octane number
Octadecan-1-ol, C18H38O
Octanol
16.1.1e Pentane, (C5H12)
16.1.1c Propane, (C3H8)
3.41.4 Reduce copper oxide with natural gas, methane
16.1.1a.02 Tests for methane gas, burn methane
16.1.1.1.0 Alkanes, (CnH2n+2), paraffins
Alkanes, cyclohexane, heptane, hexane, liquefied petroleum gas (LPG), octane, pentane, petroleum spirit
Alkanes: methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane . . .
16.1.1.1 Alkanes, (CnH2n+2), paraffins
Alkanes, skeletal formula: See diagram 16.1.1
16.1.1.0 Acyclic hydrocarbons, alkanes, alkenes, alkynes, (List)
3.28.4 Collect and weigh the gaseous products of a burning candle:
16.1.1.01 Formation of alkanes
16.1.1.1d Friedel-Crafts reaction
16.2.2 Halogen compounds, haloalkanes, (alkyl halides), halogen derivatives
16.2.4.4 Nitroalkanes, (nitroparaffins), (CnH2n+1NO2)
16.1.0 Organic chemistry
16.2.4.6 Oximes (hydrox-imino-alkanes), Group: (C:NOH)
16.1.12.1 Petroleum gas, (See 16.1.12.1 to 16.1.12.7)
16.1.00 Prepare organic compounds, addition, oxidation, reduction, substitution (displacement)reaction
16.1.1.2.0 Alkenes, (CnH2n), olefins
16.1.1.2 Alkenes, (CnH2n), olefins
16.1.1.2.1 Prepare ethene, (ethylene), C2H4
16.1.1.2.2 Dienes, isoprene units
16.1.1.3.0 Alkynes, (CnH2n-2), acetylenes
16.1.1.3 Alkynes, (CnH2n-2), acetylenes
16.1.1.3.1 Prepare ethyne (acetylene)
16.4.6 Tests for gases from burning hydrocarbons
16.1.1.1b Arenes, benzene
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
Alcohols, R-OH, -OH hydroxyl, Prefix: hydroxy-, Suffix: -ol (-OH: alcohol), (alkanol, alkyl alcohol)
6.6.18 Alcoholic fermentation, yeast Saccharomyces cerevisiae, (Exp.)
16.1.3.0 Alcohols, phenols, thiols, ethers, epoxy compounds, acetates (ethanoates), benzoyls, acetals
16.1.3.1.1 Alcohols, primary, secondary and tertiary aliphatic alcohols, rubbing alcohol
16.1.3.B Butanol, butyl alcohol, (C4H9OH)
16.1.3.2.1 Carbolic acid, phenol, TCP, Dettol
16.1.3.2.3 Cresols
16.1.3.0.1 Dihydric alcohols, glycol
1.4 List of alcohols
16.1.3.2.2 Naphthols
16.1.3.0.3 Nitroglycerine (UK), nitroglycerin (USA)
16.1.3.0.4 Nitrocellulose, gun cotton
12.12.4 Oxidation of glycerol by potassium permanganate
16.1.3.2 Phenols, group: (OH-C), in a benzene ring, Phenol = (C6H5O6)
19.1.0.4 Polyhydric alcohols
4.3.8 Prepare alcohol using immobilized yeast cells, (Exp.)
16.1.3.1.2 Prepare sodium ethoxide
16.1.3.A Propanol, propyl alcohol, (C3H7OH)
16.1.3.2a Pyrogallol
16.1.3.2.4 Resorcinol
16.1 3.2.5 Triclosan, organohalogens
16.1.3.0.2 Trihydric alcohols, glycerol
16.1.3.3 Thiols, mercaptans, thio alcohols, Thioalcohols group: (-SH), Suffix: (-thiol), (SH in an organic compound)
16.1.13 Prepare triodomethane, (iodoform)
16.1.14 Prepare trichloromethane gas, (chloroform)
16.1.14.1 Reaction of acetone with bleaching powder
16.1.14.2 Reaction of ethyl alcohol with bleaching powder
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
16.2.5.0 Nitrogen compounds, two or more nitrogen atoms
16.2.5.1 Azide compounds
16.2.5.2 Azo compounds
Benzopurpurin
16.2.5.3 Diazo compounds
16.2.5.4 Phenylhydrozone compounds
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
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
16.1.3.3 Thiols (mercaptans)
16.1.3.3.2 Allyl mercaptan
16.1.3.3.1 Methyl mercaptan
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 bonds, =, or triple bonds, ≡.
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, addition, oxidation, reduction, substitution (displacement)reactions
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 + ½ 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).
16.1.1.0 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.
16.1.1.01 Formation of alkanes
1. Hydrogenation of alkenes --> alkanes
CH2=CH2 + H2 --> CH3-CH3 (Pt catalyst)
ethylene + hydrogen --> ethane
CH3CH=CHCH3 + H2 --> CH3CH2CH2CH3 (Pt catalyst)
2. Decarboxylation (remove CO2) from molecules that have - COOH group.
RCOONa + NaOH --> R-H + Na2CO3 (dry distillation with soda lime)
CH3COONa + NaOH --> CH4 + Na2CO3
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.
Saturated hydrocarbons, e.g. hexane, C6H14, all carbons have either four or three hydrogens bonded to them and no double bonds, triple bonds or rings, react in almost the same way.
16.1.1.1a Cycloalkanes
Cycloalkanes are saturated hydrocarbons with a ring of carbon atoms, e.g. cyclopropane, C3H6, 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
Benzene, C6H6, has a stable six-sided ring structure. 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. 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 methyl benzene.
benzene + CH3+ --> benzene-CH3 + H+
CH3Cl +AlCl3 --> CH3+ + AlCl4-
16.1.1.1e Tests for unsaturated alkanes
1, Ignition tests for unsaturation
Ignite a substance in an evaporating basin and observe the smoke over the flame. The darker or more sooty the smoke, the more unsaturated, e.g. aromatic compound . If clear over a luminous flame the compound is saturated, e.g. n-hexane.
2. Bromine tests for unsaturation.
Bromine is a coloured compound but it reacts with with double bonds or triple bonds to form a colourless brominated compound.
alkene or alkyne + bromine water, yellowish colour disappears.
3. Decolorization of bromine water.
Hexane does not decolorize bromine water. Aromatic compounds also do not decolorize brominee water because they are stable compounds.
4. Baeyer test
Change in colour of the reagent (purple permanganate to brown manganese dioxide), redox reaction. Brominate hexane and other saturated hydrocarbons with the right wavelength of light and shining it on the reaction vessel, or adding peroxide or by heating the reaction.
16.1.1a Methane (CH4)
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! Pull out the delivery tube before heating the water stops so that water will not 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 bad 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 ratings
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 motor car engine. In Brisbane, most " family cars" use 91 octane "unleaded petrol". This is the lowest octane rating of the different petrol 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.
Table 16.1.1h
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
Octadecan-1-ol, C18H38O, octadecyl alcohol, 1-octadecanol, stearyl alcohol
Use octadecan-1-ol for melting point curve experiments.
Octanol, CH3(CH2)7OH, 1-octanol, octyl alcohol, n-octyl alcohol, octan-1-ol, caprylic alcohol, Flammable
3.10.0 Poisons and First Aid: See Octanol
16.1.1.2 Alkenes (CnH2n), olefins
Alkene R1R2C=CR3R4, (double CC bond =), Prefix: alkenyl-, Suffix: -ene (no principal functional group)
Alkene, (olefins, olefines), CnH2n, e.g. ethylene, ethene C2H4
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)
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 heating stops 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
Alkyne, R1-C≡C-R2, (triple CC bond involves 6 electrons , e.g. acetylene, H−C≡C−H),
Alkyne, Prefix: alkynl-, Suffix: -yne (no principal functional group), (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 ethyne (acetylene)
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.
16.1.3.0 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. 1-butanol, butan-1-ol, n-butanol, n-butyl alcohol, (biobutanol), (a primary alcohol or 1-alcohol), product of carbohydrate fermentation, common flavorant
2. 2-butanol, butan-2-ol, secondary 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-methypropan-2-ol, 2methyl-1-propanol, tert-butanol, t-butanol, tert-butyl alcohol, C4H10O, (CH3)3COH, (simplest tertiary alcohol, hydroxyl on the same carbon with three methyl groups.), paint remover, solvent
2-butoxyethanol, butyl glycol, butyl cellosolve, C4H9OCH2CH2OH, butyl ether of ethylene glycol, pH 11, in window cleaner "Windex", inks, paint solvents
16.1.3.0.1 Dihydric alcohols, glycol
The dihydric alcohols, glycols, diols, have two hydroxyl 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 hydroxyl 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.
16.1.3.0.4 Nitrocellulose, gun cotton
This preparation is too dangerous to be done in schools.
Potassium nitrate is dissolved in concentrated sulfuric acid to produce a dangerous vapour, then cooled in an ice and salt mixture, then cotton balls are added. Later more sulfuric acid is added, then the cotton balls are removed and placed in sodium bicarbonate solution until no more bubbles form, then dried.
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
1.1 Allyl alcohol, CH2:CHCH2OH, prop-2-en-1-ol, 2-propen-1-ol, Highly toxic by all routes
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 by-products, 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 loses a proton, H+ ion, to form a phenoxide ion, C6H5O-.
Phenol reacts with alkalis: phenol + NaOH (aq) <=> sodium phenoxide (aq) C6H5ONa + H2O,
sodium phenolate, C6H5ONa.3H2O
Halogenation of phenol: phenol + bromine --> 2.4.6-tribromophenol, phenol + chlorine --> 2-chlorophenol, C6H5OHCl
Carvacrol, cymophenol, C6H3CH3(OH)(C3H7), monoterpenoid phenol, in oregano herb
3. TCP, originally trichlorophenylmethyliodosalicyl, buty nowadays various phenols.
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 (α-naphthol test)
1-naphthol, C10H7OH, a-naphthol, α-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 (mercaptans)
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, α-aminodimethyl-γ-butyrothetin, in asparagus may produce malodorous methanethiol, dimethyl disulfide and dimethyl sulfone in people who eat asparagus. However, less than 50% of adults can smell these compounds in the urine. Family studies suggest that the ability to produce the odorous urine is inherited as an autosomal dominant trait.
16.1.3.3.1 Methyl mercaptan, methanethiol, CH3SH, (MeSH), colorless gas, very flammable offensive rotten cabbage smell in bad breath and flatus. in some nuts and cheese
16.1.3.3.2 Allyl mercaptan, flavouring agent, 2-propene-1-thiol, from garlic, C3H6S, EC Number (EINECS): 870-23-5
Odour threshold value: 6 × 107 molecules / mL of air
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, C2H5OC2H5, (C2H5)2O, anaesthetic "ether", ethoxyethane
16.1.3.5 Ethyl cellulose
Ethyl cellulose, cellulose ethyl ether, food additive emulsifier E462, prepared from cellulose in wood and chemically ethylated, thickening agent, filler, dietary fibre, anti clumping agent, emulsfier, no longer permitted as emulsifier in the EU, can be fermented in the large intestine to cause bloating, constipation and diarrhoea.
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 Acetal (alcohol + aldehyde), RCH(OR')2, where R and R' = organic radicals and R may be hydrogen
Acetal, 1,1-diethoxy ethane, CH3CH(OC2H5)2, is a colourless flammable solvent, 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)
16.1.5.4 Saturated hydrocarbons, e.g. hexane, C6H14
All carbon atoms in the compound have either four or three hydrogens bonded to them and no double bonds, triple bonds or rings. They react in almost the same way,as in ignition test and bromine water test
16.4.7.0 Tests for unsaturated hydrocarbons, bromine water tests for unsaturation
16.4.7.2 Tests for unsaturated hydrocarbons, ignition tests for unsaturation
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)
Carbamates
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)
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, Toxic if ingested:
Acrylamide, C3H5NO, 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: Trichloromethane
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)
16.1.14.1 Reaction of acetone with bleaching powder
CH3COCH3 + 3Cl2 --> CCl3COCH3 + 3HCl
2CCl3COCH3 + Ca(OH)2 --> 2CHCl3 + (CH3COO)2Ca
Ca(OH)2 + 2HCl --> CaCl2 + 2H2O
16.1.14.2 Reaction 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)
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
Reactions of chlorine or bromine in ultraviolet light
CH4 + Br2 --> CH3Br + HBr
CH3Br + Br2 -->CH2Br2 + HBr
CH2Br2 + Br2 --> CHBr3 + HBr
CHBr3 + Br2 -->CBr4 + HBr
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),Repeat unit: -[CF2=CF2]n-, C2F4
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-
Carbide are binary compounds of:
1. C + electropositive element, e.g, calcium carbide.
2. C + heavy metal for cutting tools, e.g. aluminium carbide (Al4C3), chromium carbide, Cr3C2, iron carbide Fe3C (cementite),
Tungsten carbide ("carbide", WC), used for cutting tools, milling tools, abrasives, jewellery, Young's modulus 550CPa
Iron carbide is formed with carbon monoxide when iron oxide is heated with charcoal.
3Fe2O3 +11C --> 2Fe3C + 9CO (g)
Types of carbides
1. Methanides, CH3-
Hydrocarbyl anions, methyl anion, conjugate base of methane
Methanides + water --> methane, e.g. aluminium carbide, (Al4C3)
2. Acetylides, e.g. sodium carbide Na2C2, Lanthanum carbide LaC2, copper (I) acetylide Cu2C2
See Acetylene
Acetylides (percarbides, C22-) + water --> acetylene, e.g. Na2C2, CaC2
Calcium carbide CaC2, (calcium dicarbide, "carbide", calcium acetylide, acetylenogen, ethnide dicarbide, Toxic by all routes
CaC2 + 2H2O --> C2H2 + Ca(OH)2
calcium carbide + water --> acetylene + calcium hydroxide
3. Sesquicarbides, e.g. Mg2C3
4. Covalent carbides, e.g. Boron carbide B4C
Silicon carbide, SiC, carborudum abrasive, moissanite synthetic gemstone, emery paper, sanding paper, sharpening stone, fine particles, Toxic by inhalation
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), (HOCC≡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, C3H6N6, 2,4,6-​triamino-​1,3,5-​triazine 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.
Melamine-formaldehyde, (MF), C4H6N6O, hard to ignite, alkaline fumes, burns with pale yellow flame (light blue-green edge), formaldehyde and fish-like smell, thermosetting plastic, retains strength and shape on heating
Commercial
Melamine crockery, green, virtually unbreakable, dishwasher safe, Not suitable for microwave oven, plate, 18 mm diameter
16.2.4.3.00 Amines, aliphatic amines (RNH2-, R = alkyl group), ionization reaction of methylamine
Amines have lower boiling temperatures than alcohols. Methylamine and ethylamine are gases at room temperature. Longer chain amines are volatile liquids with rotten fishy smells characteristic of decomposing proteins, and are bases, (can accept a H+ ion), so can react with acids to form salts and lose the fishy smell.
1. Primary amines: R-NH2
NH2- = amino group, e.g. methylamine (CH3-NH2), ethylamine (CH3CH2-NH2), phenylamine (aniline) C6H5-NH2 (has benzene ring), phenylamine is used in lava lamps because alost same density as water and not soluble in water, so rises when heated by bulb below and falls when cooled by air at the surface
2. Secondary amines: R2-NH
NH = imino group, e.g. dimethylamine (CH3)2NH
3. Tertiary amines: R3-N
N = nitrogen, e.g. trimethylamine (CH3)3N, triethylamine, (C2H5)3N
16.2.4.3.01 Methylamine ionization reaction
CH3NH2 + H2O <--> CH3NH3+ + OH-
methylamine + water <--> methylammonium ion + hydroxide ion
16.2.4.3.02 Prepare phenylamine
1. Benzene + conc. nitric acid + conc. sulfuric acid --> nitrobenzene, C6H5NO2
2. Nitrobenzene + tin catalyst Sn + reducing agent hydrochloric acid --> phenylamine + water
C6H5NO2 + 6 H+ --> C6H5NH2 + 2H2O
16.2.4.3.03 Nitrosamines
Nitrosamines are produced by reaction of nitrous acid with secondary amines. They can be formed in the gut when nitrites react with amino acids.
C4 explosive, H8N8O8, HMX, Octogen, detonator, solid rocket propellent, mainly cyclonite or cyclotrimethylene trinitramine
RDX explosive (Research Department Explosive, C3H6N6O6, Cyclonite, Hexagen, used against German submarines during World War II
16.2.4.3.04 Nitramine, (acid-base indicator, 3.5), C7H5N5O8, tetryl. colourless-yellow crystals, explosive formerly used in munitions
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
Ethyl cyanoacrylate, "Superglue", BE CAREFUL! Do not squirt in the eye! Toxic by all routes,
Commercial:  Ethyl 2-cyanoacrylate, liquid, C6H7NO2
GBL, γ-butyrolactone is a naturally occurring colourless oily liquid with a characteristic odour used as a stain remover and stripper, (including Superglue).
16.2.5.1 Azide compounds
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 compounds
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')
Benzopurpurin, acid-base indicator, 1-naphthalene sulfonic acid, benzopurpurin 4b, C34H26N6O6S2, sodium salt C34H26N6O6S2Na2, direct red, cotton red 4b, red acid dye, changes from blue-violet to red in the pH range 1.2-4.0, formerly used as a stain and as an indicator, used in liquid crystal displays, inks, dyes, microorganism stains.
16.2.5.3 Diazo compounds
Diazonium ion R-N+≡N, diazonium compounds [(RN≡N+) Cl-], e.g. diazomethane (CH2=N2)
HNO2 and HCl + R-NH2 --> R-N+≡N + Cl-
nitrous acid and hydrochloric acid + amines --> diazonium ion + chloride ion
HNO2 + HCl + C6H5NH2 --> C6H5N2Cl + 2H2O
nitrous acid and hydrochloric acid + phenylamine --> benzenediazonium chloride + water
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]
Allyl isothiocyanate (AITC), CH2CHCH2NCS, colorless oil, taste of mustard, horseradish, wasabi
16.2.8.2 Sulfides: RSR (R not equal to H), (old name: thioethers)
Diallyl disulfide C6H10S2, organosulfur compound, from garlic and other Allium species, Alliaceae. People who eat asparagus may notice a malodrous over-boiled cabbage smell in their urine because of sulfur compounds, e.g. diallyl disulfide, dimethyl sulfide, dimethylsulfone, sulfimides (sulfilimines): (H2S=NH)
Oil of garlic contains diallyl disulfide, diallyl trisulfide and diallyl tetrasulfide, crushing garlic produces allicin, C6H10OS2. Diallyl disulfide has health benefits for most people, but some people are allergic to it and most Allium species.
16.2.8.4 Sulfonium compounds: R3S+, [SR3]+
Sulfonium salts, e.g. trimethylsulfonium chloride [(CH3)3S]+Cl-, Cyclopropyldiphenylsulfonium tetrafluoroborate, C15H15BF4S
16.2.8.5 Thiocyanates: [RC(=O)SN] salts and esters of thiocyanic acid HSCN, e.g. methyl thiocyanate (CH3SC≡N)
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.
16.2.8.9 Sulfoxide, R–S(=O)–R',
1. Propanethial S-oxide, C3H6OS, lachrymatory factor from cut onion cells, Allium cepa, formed when enzyme allinase reacts with S-1-propenyl-L-cysteine sulfoxide
2. Dimethyl sulfoxide, (DMSO, (CH3)2SO, C2H6OS): 16.2.8.6
3. L-Alliin, C6H11NO3S, ACSO, S-Allyl-L-cysteine sulfoxide, SAC
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.