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(c) doc b(c) doc b

Doc Brown's Chemistry  Revising Advanced Level Organic Chemistry

Revision Notes Part - ORGANO-NITROGEN COMPOUNDS

The Classification, Molecular Structure and Nomenclature-naming of Organic compounds containing Nitrogen in the molecules

 Nomenclature of organic nitrogen compounds examples of how to name 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, acid nitriles via displayed formula of molecules, graphic formula, molecular formula, skeletal formula, structural formula of various homologous series. naming empirical molecular formula graphic formula displayed formula skeletal formula structural isomers isomerism. Some 'old' names are quoted in (), but their use should be avoided if possible.

Fast track to nomenclature examples of organo-nitrogen compounds .. 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


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), CH5N, (c) doc b, (c) doc b, (c) doc b, (c) doc b

ethylamine (aminoethane), molecular formula C2H7N, (c) doc b, (c) doc b, displayed/graphic structural formula(c) doc b, skeletal formula (c) doc b

propylamine, (1-aminopropane), C3H9N, (c) doc b,(c) doc b, (c) doc b

2-aminopropane, (c) doc b, (c) doc b

butylamine, (1-aminobutane),  C4H11N,(c) doc b, (c) doc b

2-aminobutane, (c) doc b, (c) doc b 

1-aminopentane (pentylamine), C5H13N, (c) doc b, (c) doc b

2-aminopentane, (c) doc b, (c) doc b

3-aminopentane, (c) doc b, (c) doc b

1-aminohexane (hexylamine), C6H15N, (c) doc b, (c) doc b

2-aminohexane, (c) doc b, (c) doc b

3-aminohexane, (c) doc b, (c) doc b

examples of primary diamines:

1,2-diaminoethane, C2H8N2, (c) doc b, (c) doc b, (c) doc b

1,3-diaminopropane, C3H10N2, (c) doc b, (c) doc b

1,4-diaminobutane, C4H12N2, (c) doc b, (c) doc b

1,5-diaminopentane, C5H14N2, (c) doc b, (c) doc b

2,3-diaminopentane, (c) doc b, (c) doc b

2,4-diaminopentane, (c) doc b, (c) doc b

1,4-diaminohexane, C6H16N2, (c) doc b, (c) doc b

1,6-diaminohexane, (c) doc b, (c) doc b

examples of primary cyclo-amines: e.g.

cyclopentylamine, aminocyclopentane, C5H11N2, (c) doc b ,(c) doc b

aminocyclohexane, cyclohexylamine, C6H13N2, (c) doc b, (c) doc b

benzylamine, C7H9N, (c) doc b 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 , C6H7N, C6H5NH2 phenylamine (aniline) (c) doc b

1,3-diaminobenzene, C6H8N2(c) doc b 3-aminobenzoic acid,  (c) doc b

2-methylphenylamine, methyl-2-phenylamine, 1-amino-2-methylbenzene (c) doc b ,

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, (c) doc b,(c) doc b, (c) doc b

ethylmethylamine, (c) doc b, (c) doc b

diethylamine, (c) doc b, (c) doc b

methylpropylamine, (c) doc b, (c) doc b

ethylpropylamine, (c) doc b, (c) doc b

dipropylamine, (c) doc b(c) doc b

examples of cyclo-secondary amines: e.g.

piperidine, C5H11N, (c) doc b, (c) doc b

N-methylcyclopentylamine, C6H13N, (c) doc b, (c) doc b

examples of secondary AROMATIC amines: e.g.

N-methylphenylamine, C7H9N, (c) doc b, N-ethylphenylamine, C8H11N,(c) doc b

and  diphenylamine, C12H11N,(c) doc b


TERTIARY AMINES

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

ALIPHATIC: trimethylamine, (c) doc b ,(c) doc b

ethyldimethylamine, (c) doc b, (c) doc b

diethylmethylamine, (c) doc b ,(c) doc b

triethylamine, (c) doc b, (c) doc b

two examples of cyclo-tertiary amines:

N-methylpyrrolidine, (c) doc b ,(c) doc b

and N-methylpiperidine, (c) doc b, (c) doc b

examples of tertiary AROMATIC amines: e.g.

N,N-dimethylphenylamine (c) doc b, N,N-diethylphenylamine (c) doc b

and triphenylamine (c) doc b


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, C2H5NO2, (c) doc b, (c) doc b, (c) doc b, (c) doc b, (c) doc b

2-aminopropanoic acid, C3H7NO2, (c) doc b, (c) doc b, (c) doc b, (c) doc b, (c) doc b

 3-aminopropanoic acid ,(c) doc b ,(c) doc b , (c) doc b, (c) doc b


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.

methanamide, CH3NO, (c) doc b,(c) doc b,(c) doc b

ethanamide, C2H5NO, (c) doc b,(c) doc b ,(c) doc b , (c) doc b

propanamide, C3H7NO, (c) doc b, (c) doc b, (c) doc b

butanamide, C4H9NO, (c) doc b, (c) doc b, (c) doc b

pentanamide, C5H9NO, (c) doc b, (c) doc b, (c) doc b

benzamide, C7H7NO,(c) doc b, (c) doc b,(c) doc b, (the simplest primary aromatic acid amide)


SECONDARY ACID AMIDES

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

N-methylethanamide, (c) doc b; N-phenylethanamide, (c) doc b

N-methylbenzamide, (c) doc b; N-phenylbenzamide, (c) doc b 


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 (c) doc b is the basic condensation 'polymeric' process.

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

(c) doc b

(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!)  (c) doc b displayed graphical formula

or the skeletal formula  (c) doc b

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 'side chain' 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 (c) doc b, (c) doc b

nylon-6 (c) doc b, (c) doc b

nylon-7 (c) doc b, (c) doc b

nylon-8 (c) doc b, (c) doc b

nylon-9 (c) doc b, (c) doc b

nylon 10 (c) doc b, (c) doc b

nylon-3,7 (c) doc b, (c) doc b

nylon-4,6 (c) doc b, (c) doc b

nylon-4,8 (c) doc b, (c) doc b

nylon-5,7 (c) doc b, (c) doc b

nylon-6,6 (c) doc b, (c) doc b

nylon-7,7 (c) doc b, (c) doc b

nylon-7,9 (c) doc b, (c) doc b

nylon-7,11 (c) doc b, (c) doc b


TERTIARY ACID AMIDES

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

N,N-dimethylethanamide, (c) doc b, (c) doc b

N,N-dimethylbenzamide, (c) doc b


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) (c) doc bfrom phenylamine+

(2) (c) doc bfrom 4-methylphenylamine

(3) (c) doc bfrom 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 (c) doc b

reacting (1) with phenylamine gives (c) doc b

reacting (2) with phenol gives(c) doc b 

reacting (2) with phenylamine gives (c) doc b


NITRO-AROMATICS

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

nitrobenzene, C6H5NO2, (c) doc b; 1,3-dinitrobenzene, C6H4N2O4, (c) doc b

methyl-2-nitrobenzene, C7H7NO2, (c) doc b; 3-nitrobenzoic acid, (c) doc b


NITRILES

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), (c) doc b, (c) doc b, (c) doc b

ethanenitrile (ethanonitrile, acetonitrile), C2H3N, (c) doc b, (c) doc b, (c) doc b, (c) doc b, (c) doc b, (c) doc b

propanenitrile (propanonitrile, ethyl cyanide), C3H5N, (c) doc b, (c) doc b, (c) doc b, (c) doc b, (c) doc b, (c) doc b

2-hydroxypropanenitrile, CH3CH(OH)CN,

2-hydroxy-2-methylbutanenitrile,


WHAT NEXT?

Fast track to nomenclature examples of organo-nitrogen compounds .. 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 * (c) doc b type in name quiz on N compounds

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

The shapes and bond angles of simple molecules - section on bond angles in organic molecules

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, WJEC GCE AS A2 Chemistry, CCEA/CEA GCE AS A2 Chemistry revising courses for pre-university students (equal to US grade 11 and grade 12 and AP Honours/honors level courses)

formula keywords: how to name naming nomenclature empirical molecular formula graphic formula displayed formula skeletal formula structural isomers isomerism prim Primary amines .. sec Secondary amines .. tert 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 .. acid Nitriles CH5N CH3NH2 C2H7N C2H5NH2 CH3CH2NH2 C3H9N C3H7NH2 CH3CH2CH2NH2 C4H11N C4H9NH2 CH3CH2CH2CH2NH2 C5H13N C5H11NH2 CH3CH2CH2CH2CH2NH2 C6H13N C6H13NH2 C2H8N2 H2NCH2CH2NH2 NH2CH2CH2NH2 C3H10N2 H2NCH2CH2CH2NH2 NH2CH2CH2CH2NH2 C4H12N2 H2NCH2CH2CH2CH2NH2 NH2CH2CH2CH2CH2NH2 C5H14N2 H2NCH2CH2CH2CH2CH2NH2 NH2CH2CH2CH2CH2CH2NH2 C6H16N2 H2NCH2CH2CH2CH2CH2CH2NH2 NH2CH2CH2CH2CH2CH2CH2NH2 C5H11N C6H13N C7H9N C6H5CH2NH2 C6H7N C6H5NH2 C6H8N2 C5H11N C6H13N C6H5NHCH3 C6H5NHCH2CH3 C7H9N C8H11N C12H11N C6H5NHC6H5 C18H15N C2H5O2N C2H5NO2 H2NCH2COOH NH2CH2COOH C3H7O2N C3H7NO2 H2NCH2CH2COOH NH2CH2CH2COOH CH3CH(NH2)COOH CH3NO HCONH2 C2H5NO CH3CONH2 C3H7NO CH3CH2CONH2 C4H9NO CH3CH2CH2CONH2 C5H9NO CH3CH2CH2CH2CONH2 C7H7NO C6H5CONH2 C6H5NO2 C6H4N2O4 C7H7NO2 CH3C6H5NO2 HCN CHN C2H3N CH3CN C3H5N CH3CH2CN

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