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GCE-AS-A2-IB Advanced Level Organic Chemistry Revision Notes on the Classification, Structure and Nomenclature-naming of Organic compounds containing Nitrogen 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 Some 'old' names are quoted in (), but their use should be avoided if possible. Email query?comment * allow time for graphic images/pictures to download m/c quiz on structure/names of N compounds * type in name quiz on N compounds 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,
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, 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) 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 and diphenylamine 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 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 , 3-aminopropanoic acid , 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. methanamide, ethanamide , propanamide , butanamide , pentanamide , benzamide, These have one hydrogen and one alkyl or aryl group on the N of the amide group. N-methylethanamide, N-methylbenzamide, 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
(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!) (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 nylon-7,11 hese 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) + HNO2(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) (2) (3) 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, methyl-2-nitrobenzene, 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, ethanenitrile, propanenitrile, Revision notes for studying revising tutoring teaching Advanced Level GCE AS A2 CHEMISTRY courses in unofficial support the Chemistry in any advanced-subsidiary AQA, Edexcel, OCR, CIE, WJEC, SQA and CCEA (NI) UK or Cambridge/London/Edexcel International and OCR/CIE and International Baccalaureate (IB) examinations. * Copyright © Dr W P Brown 2000-2008 All rights reserved including the revision notes pages, quizzes, worksheets etc. * Doc Brown's Chemistry Clinic * www.docbrown.info/ * |
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