Revision notes for GCE Advanced Subsidiary Level AS Advanced Level A2 IB Revise AQA GCE Chemistry OCR GCE Chemistry Edexcel GCE Chemistry Salters Chemistry CIE Chemistry revising courses for pre-university students (equal to US grade 11 and grade 12 and Honours/honors level courses)

Examples of displayed formula of molecules, graphic formula, molecular formula, skeletal formula, structural formula of these homologous series. Some 'old' names are quoted in (), but their use should be avoided if possible.

Fast track to nomenclature examples of .. Primary amines .. Secondary amines .. Tertiary Amines .. Quaternary ammonium salts .. Amino acids and zwitterions .. Primary acid amides .. Secondary acid amides .. Polyamides (nylons) & polypeptides .. Tertiary acid amides ... Diazonium salts and azo dyes .. Nitro-aromatics .. Nitriles

summary of functional groups and homologous series * organic chemical identity tests

m/c quiz on structure/names of N compounds * type in name quiz on N compounds

Intermolecular forces & boiling points of primary aliphatic amines & amides compared to other organic molecules

PRIMARY AMINES

These have two hydrogen atoms and one alkyl or aryl group attached to the nitrogen to form the amine or amino group -NH₂.

ALIPHATIC: methylamine (aminomethane), , , ,

ethylamine (aminoethane), , , ,

propylamine, (1-aminopropane), ,,

2-aminopropane, ,

butylamine, (1-aminobutane), ,

2-aminobutane, ,  

1-aminopentane, (pentylamine) ,

2-aminopentane, ,

3-aminopentane, ,

1-aminohexane, (hexylamine), ,

2-aminohexane, ,

3-aminohexane, ,

examples of primary diamines:

1,2-diaminoethane, , ,

1,3-diaminopropane, ,

1,4-diaminobutane, ,

1,5-diaminopentane, ,

2,3-diaminopentane, ,

2,4-diaminopentane, ,

1,4-diaminohexane, ,

1,6-diaminohexane, ,

examples of primary cyclo-amines: e.g.

cyclopentylamine, aminocyclopentane, ,

aminocyclohexane, cyclohexylamine, ,

benzylamine, aliphatic, NOT aromatic, compare with one of its isomers 2-methylphenylamine below.

examples of primary AROMATIC amines where the amino or amine group is directly attached to the aromatic benzene ring ....

e.g. the simplest is C₆H₅NH₂,  phenylamine (aniline)

1,3-diaminobenzene,  ,  3-aminobenzoic acid, 

2-methylphenylamine, methyl-2-phenylamine, 1-amino-2-methylbenzene  ,

this is isomeric with phenylmethylamine or benzylamine, which is a primary aliphatic amine because the amine group is NOT directly attached to the benzene ring.

(note: that many 'amino acids' are 'primary' amines - see below)

SECONDARY AMINES

These have one hydrogen atom and two alkyl or aryl groups attached to the nitrogen

ALIPHATIC: dimethylamine, ,,

ethylmethylamine, ,

diethylamine, ,

methylpropylamine, ,

ethylpropylamine, ,

dipropylamine, , 

examples of cyclo-secondary amines: e.g.

piperidine, ,

N-methylcyclopentylamine, ,

examples of secondary AROMATIC amines: e.g.

N-methylphenylamine, N-ethylphenylamine

and  diphenylamine

TERTIARY AMINES

These have no hydrogen atom and three alkyl or aryl groups attached to the nitrogen

ALIPHATIC: trimethylamine, ,

ethyldimethylamine, ,

diethylmethylamine, ,

triethylamine, ,

two examples of cyclo-tertiary amines:

N-methylpyrrolidine, ,

and N-methylpiperidine, ,

examples of tertiary AROMATIC amines: e.g.

N,N-dimethylphenylamine , N,N-diethylphenylamine

and triphenylamine

QUATERNARY AMMONIUM SALTS

If all for hydrogens of an ammonium ion are replaced with alkyl or aryl groups then an ionic quaternary salt is formed.

e.g. the simplest is tetramethylammonium chloride, (CH₃)₄N⁺ Cl^-

tetrapropylammonium chloride, (CH₃CH₂CH₂)₄N⁺ Cl^-

and the R groups can be mixed e.g. [(CH₃CH₂CH₂)₃NC₆H₅]⁺ Cl^-

AMINO ACIDS and ZWITTERIONS

The primary suffix name for an aliphatic carboxylic acid is based on the "longest carbon chain name *" for the -COOH bond system e.g.  ethanoic acid, propanoic  acid etc. The amino group -NH₂, with its C-atom position number, is added as a prefix. [* without the end 'e'] Many amino-acids in aqueous solution, or in the crystalline state, exist as 'zwitterions' where the proton migrates from the acidic -COOH group to the basic -NH₂  group to form the ionic groups -NH₃⁺ and -COO^- BUT within the same 'molecule'.

aminoethanoic acid, , , , ,

2-aminopropanoic acid , , , , ,

PRIMARY ACID AMIDES

The primary suffix name for an aliphatic acid amide is based on the "longest carbon chain name *" + "amide" for the CONH₂ bond system at the end of the carbon chain e.g. methanamide, ethanamide etc. [* without the end 'e'] There are two hydrogens on the N of the amide group.

These have one hydrogen and one alkyl or aryl group on the N of the amide group.

N-methylethanamide, ; N-phenylethanamide,

N-methylbenzamide, ; N-phenylbenzamide,  

POLYAMIDES and POLYPEPTIDES are secondary amides formed in a condensation reaction between a carboxylic acid and an amine. Water is eliminated between the two 'monomers' to give the secondary, polyamide (polymer) or polypeptide (if in proteins) linkage ...

-COOH + H₂N- ==> -CO-NH- + H₂O is the basic condensation 'polymeric' process.

(1) KEVLAR is formed from benzene-1,4-dicarboxylic acid and 1,4-diaminobenzene

(2) in proteins, amino acids link together  in a condensation reaction to form peptides e.g. Alanine (Ala, 2-aminopropanoic acid) links with Glycine (Gly, aminoethanoic acid) to form the dipeptide AlaGly (in 'biochemical' shorthand!)  displayed graphical formula

or the skeletal formula  

Proteins are built up in this way to form long chains of amino-acid residues after the elimination of water ...

i.e. nH₂NCH(R)COOH ==> -(-NH-CH(R)-CO-)_n- + n H₂O

where R is the variable 'sidechain' from the original amino acid

(3) NYLONS are formed by condensing together a dicarboxylic acid and a diamine (nylon-x,y) OR polymerising an amino carboxylic acid (nylon-y). [x = length carbon atoms in amine, y = length of carbon atoms in carboxylic acid]

nylon-5 ,

nylon-6 ,

nylon-7 ,

nylon-8 ,

nylon-9 ,

nylon 10 ,

nylon-3,7 ,

nylon-4,6 ,

nylon-4,8 ,

nylon-5,7 ,

nylon-6,6 ,

nylon-7,7 ,

nylon-7,9 ,

These have two alkyl or aryl groups attached to the N of the amide group.

N,N-dimethylethanamide, ,

N,N-dimethylbenzamide,

DIAZONIUM SALTS and AZO DYES

Diazonium salts are formed when primary aromatic amines reaction with nitrous acid

e.g. C₆H₅NH₂(aq) + HNO_2(aq) + H⁺_(aq) ==> C₆H₅N₂⁺_(aq) + 2H₂O_(l)

The diazonium cation has a nitrogen - nitrogen triple bond system directly attached to the benzene ring e.g.

(1) from phenylamine+

(2) from 4-methylphenylamine

(3) from 2-aminobenzoic acid. In alkaline solution these diazonium salts couple with phenols and aromatic amines to form azo dyes which have benzene rings linked with an azo -N=N- bond system e.g.

reacting (1) with phenol gives

reacting (1) with phenylamine gives

reacting (2) with phenol gives 

reacting (2) with phenylamine gives

NITRO-AROMATICS

These have the nitro -NO₂ group directly attached to the ring. On reduction they form primary aromatic amines.

nitrobenzene, ; 1,3-dinitrobenzene,

methyl-2-nitrobenzene, ; 3-nitrobenzoic acid,

The nitrile functional group consists of a carbon to nitrogen triple bond. The name is based on the longest carbon chain, including the C of the nitrile group.

methanenitrile (methanonitrile, hydrogen cyanide), , ,

ethanenitrile (ethanonitrile, acetonitrile), , , , , ,

propanenitrile (propanonitrile, ethyl cyanide), , , , , ,

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