6.2.1 Amines

organic compounds derived from ammonia (NH3) where 1 or more of the hydrogen atoms has been replaced by a carbon chain or ring

where the N is attached to at least 1 straight or branched carbon chain, an alkyl chain R

where the N is attached to an aromatic ring, an aryl group Ar

commonly occur in nature and have many effects on the body- e.g. serotonin as a neurotransmitter

• primary: where the N has one carbon, alkyl or aryl, group attached to it, NH2 (R) • secondary: where the N has two carbons attached to it, NH (R, R’) • tertiary: where the N has 3 carbons attached to it, N (R,R’,R’’)

• if the NH2 is present qat the end of a chain, can use suffix -amine to the name of the alkyl chain attached to, e.g. CH3H2NH2 would be ethylamine • if the NH2 is attached to any other carbon other than carbon-1, can use prefix amino , e.g. CH3CHNH2CH2CH3 is 2-aminobutane

• if containing the same alkyl group, can use prefixes di- and tri-, e.g. (CH3)2NH = dimethylamine • when 3 or more different groups attached, need to name using N-linked • smaller group is N-linked of the bigger group, and ORDERED ALPHABETICALLY • e.g. CH3CH2C-N-CH3-CH2CH3 = N-ethyl-N-methylpropylamine

behave as bases, as contain a lone pair of electrons on the N:, and can accept a hydrogen (proton)

form a dative covalent bond - e.g. CH3CH2-N:H2 + H+ → [CH3CH2NH3]+

act as bases and neutralise acids to make salts - a + goes on the N, and the -ve metal ion goes nearby • e.g. 2CH3-NH2 + H2SO4 → (CH3N+H3)2SO4-

haloalkane + :NH3 → ammonium halide salt + H2O • excess ammonia • ethanol as a solvent

• has a lone pair of electrons on the :NH3 • can act as a nucleophile in a substitution reaction with haloalkane • produces an ammonium salt • add aqueous alkali to generate the amine from the salt

haloalkane + :NH3 → ammonium salt ammonium salt + NaOH → amine + sodium salt + H2O

CH3CH2CH2Cl + NH3 → CH3CH2CH2NH3+Cl- CH3CH2CH2NH3+Cl- + NaOH → CH3CH2CH2NH2 + NaOH + H2O

• acts as a solvent • prevents substitution of haloalkane by water • which would form an alcohol

prevents the further substitution of the amine group, to 2° and 3°

primary amine + haloalkane • just a further substitution, as the N in the amine formed still contains a lone pair • continue again for tertiary

CH3CH2CH2Cl + CH3CH2CH2:NH2 → CH3CH2CH2-NH-CH2CH2CH3 + NaCl + H2O • still via forming the salt first, and then reacting with NaOH

benzene ring with at least one N attached, e.g. NH2

via reduction of nitrobenzene: 1) nitrobenzene is heated under reflux with tin and conc. hydrochloric acid 2) forms the ammonium salt phenylammonium chloride 3) the salt is then reacted with excess NaOH, to form the aromatic amine phenylamine

⌬-NO2 + 6[H] → ⌬-NH2 + 2H2O • with Sn/conc. HCl on arrow as reducing agents • and excess NaOH(aq) on bottom