17.5 1 Amines and their preparations Flashcards
Shape of amines
three bonding pairs around nitrogen
trigonal pyramidal shape
nitrogen atom has a lone pair of electrons
one alkyl group
primary
two alkyl group
secondary
three alkyl group
tertiary
example of naming
methylamine
naming
suffix is amine
methyl,ethyl,propyl ,butyl
aromatic amine
C6H5NH2
phenylamine
amines occur
in nature and many drugs e.g. amphetamines
Preparations from halogenoalkanes
Heat a halogenoalkane with ammonia
Under pressure and in a sealed container if gas
Mixed with concentrated aqueous ammonia
nucelophilic attack by lone pair of electrons on ammonia on electron-deficient carbon attom
equation for the preparation of methylamine
CH3Cl +NH3=CH3NH2+HCl
HCl reacts with NH3 to make NH4Cl so better off writing this as the product
amine formed in preparation from halogenoalkane
has a nitrogen atom containing a lone pair of electrons
could act as a nucleophile as well
would get a side reaction producing a secondary amine
how to prevent unwanted side reactions in preparations of halogenoalkanes
ammonia is used in excess
Preparations from nitriles
Reduced to primary amines
lithium tetrahydrioaluminate
reactants mixed in dry ehter to ensure no water affects the reaction
CH3CN+4[H]=CH3CH2NH2
How to prepare phenylamine
reduction of nitrobenzene
reducing agent is tin mixed with concentrated hydrochloric acid
reaction mixture is heated under reflux
oxidation of tin to tin(II) and tin(IV) ions
hydrogen produce by reaction between tin and the acid
C6H5NO2+6[H]=C6H5NH2+2H20
Phenylamine
is basic and will react with the acid present to from phenylammonium ion but can be converted into phenylamine by adding alkali such as sodium hydroxide solution
C6H5NH3+ + OH-=C6H5NH3+H20
