AMINES Flashcards
Amine
an amine is derived from ammonia molecule containing a nitrogen atom where hydrogen is replaced with an organic group.
different types of amine
primary, secondary, tertiary and quaternery
aliphatic amine
non aromatic amines are called aliphatic amines.
cationic surfactants
quaternery ammonium salts with long hydrocarbon tail are called cationic surfactants.
- quaternery ammonium salts are used to make cleaning products like shampoos, detergents etc.
what are quaternery ammonium salts made of
positive ends attracted to negative ions.
example of quaternery ammonium salt will be tetra methyl ammonium chloride.
how does cationic surfactants work on grease
- their non polar tail is attracted to oil or grease and their polar head is attracted to water which doesnt allow both of them to mix and hence removes grease from clothing.
why are cationic surfactants used in shampoos and hair conditioner and fabric washing
because cationic surfactants have a positively charged ammonium ion which is attracted to negatively charged fibre and hair
amine as a base
- amine acts as a base because the lone pair pf electrons allows them to accept a proton, proton acceptors are base.
how is proton binding to amine
via a dative covalent bond. electrons are originating from nitrogen lone pair.
strength of base depends on
- availability of lone pair of electrons on the nitrogen
- higher the electron density - more readily avaiable electrons.
what is electron density depending on
electron density depends on type of r group attatched to nitrogen.
order of base strength in amine
primary aliphatic amines > ammonia > aromatic amines
why are aromatic amines less basic?
- because benzene is an elextron withdrawing group ( delocalised electron ring) and it pulls electron from the nitrogen into the ring structure .
- electron density of nitrogen decrerases so there is less availability of lone pair hence aromatic amines are more basic.
why are primary aliphatic amines more basic
- because primary aliphatic amines contain an alkyl group
- alkyl group pushes away the electrons into the nitrogen .
- electron density at nitrogen increases so there is an increased availability of lone pairs
- thus making primary aliphatic amines more basic.
nucleophiles
amines are nucleophiles with lone pairs and loves nucleus
process of making primary aliphatic amines
- reacting halogenoalkane with excess ammonia
- reducing nitriles
forming primary amines bybreducing nitrile
reducing nitriles using a nickel catalyst and hydrogen gas.
reacting halogenoalkane and excess ammonia produces
primary aliphatic amine and ammonium chloride salt.
disadvantage of rxn between halogenoalkane and excess ammonia
- along with primary amines, secondary , tertiary and quaternery salts are also produced making an impure product.
- primary amine still has lone pair which can react with remaining halogenoalkane to produce secondary amines further and tertiary and quaternery salts.
catalytic hydrogenation
production of primary amines by reducing nitrile using hydrogen gas and a nickel or platinum catalyst
conditions for catalytic hydrogenation
- nickel as a catalyst and high temperature and pressure.
reduction for aliphatic amine
using a strong reducing agent lialh4 and dilute acid.
- dissolved in dry non aqueous solvent such as dry ether.
how do we make aromatic amines
by reducing nitro benzenes
where are aromatic amines used
dye stuffs and pharmeceuticals