3.3.11 amines Flashcards
what are the 4 structures/types of amines
primary = 1 alkyl group attached to NH2
secondary = 2 alkyl groups attached to NH
tertiary = 3 alkyl groups attached to N
quaternary = 4 alkyl groups attached to N
what are the 2 methods of forming amines
nucleophilic substitution and reduction of nitriles
what conditions are required to form a quaternary amine via nucleophilic substitution
excess of the halogenoalkane
what conditions are required to form primary amines via nucleophilic substitution
excess ammonia
2 equations for the reduction of nitriles, using propylnitrile
CH3CH2Br + CN- –> CH3CH2CN + Br-
CH3CH2C≡N + 4[H] –> CH3CH2C2NH2
what are the conditions required for the reduction of nitriles
aqueous ethanol + heated under reflux with KCN in step one
LiAlH4 in ether or H2 with a Ni catalyst in step two
use of quaternary amines
quaternary amines can react with chloride or bromide ions to form quaternary amine salts. they are used as cationic surfactants which are used in fabric softners and hair conditioners
discuss the base strength of primary amines, ammonia and aromatic amines
primary amines = most effective base as the lone pair on the nitrogen is more available as the methyl group allows for an inductive effect as the CH3 pushes electrons onto the N
aromatic amines = least effective base as the lone pair on the nitrogen is less available as it becomes delocalised due to the electron ring of benzene
ammonias base strength is in between primary amines and aromatic amines
how are aromatic amines produced
nitrobenzene reacts with a reducing agent - 6[H]
to form an intermediate phenylammonium salt which will react with NaOH to form the phenylamine and 2H2O
a tin catalyst is used with conc HCl and heated under reflux.
what is the difference between aliphatic amines and aromatic amines
aliphatic - when there are alkyl groups attached to NH2
aromatic - when there are benzene rings attached to NH2
aromatic amines are used for what?
the manufacture of dyes
