amines Flashcards
what is amine?
N atom bonded with alkyl groups
what is the differences in primary secondary tiertary quarternary amines
primary amine bonded to one alkyl group Ch3-NH2
secondary amine bonded to 2 alkyl group Ch3-NH-ch3
tertiary amine bonded to 3 alkyl group Ch3-N-ch3
ch3
ch3
quarternary amine bonded to 4 alkyl group Ch3- N+ CH3
ch3
difference to aliphatic and aromatic compounds
Aliphatic N bonded to alkyl groups
Aromatic N bonded to benzene
what are quaternary amines used for?
cleaning products e.g washing liquid
how do cationic surfactants work to remove oil?
CH3
they have a hydrocarbon tail CH3CH2Ch2CH2 -N+ CH3
CH3
This non polar tail is attracted oil
the positively charge polar headis attracted to water as water is polar
This allows them to mix and remove grease
how do cationic surfactants static hair?
the positivel charged ammonium ion is attractedto negatively charged hair fibres removing static
what is a cationic surfactant?
quaternary ammonium salt with a long hydrocarbon chain (tail)
How do amines act as a base?
they have a lone pair this allows them to bond with protein and form coordinate/ dative convalent bonds both electrons of the nitrogen bond with the the proton
how is the strength of base of the amine determined?
the strength of the base is determined by its availiability of the electrons on the lone pair. The higher the electron density the higher the availibilty
The electron density is based on the group attached to the nitrogen
what is the order of base strength?
aromatic amines>ammonia>aliphatic amines
why are aromatic amines the weakes bases and aliphatic amines the strongest
benzene ring draws in electrons this pulls (negative inducing effect) the lone pair closer to itself reducing electron density at nitrogen. This makes the lone pair less available and aromatic amines less basic
alkyl groups are electron pushing groups (positive inducing effect).This pushes electrons towards the nitrogen increasing the electron density hence increasing lone pair availability makine aliphatic amines more basic
what are the two methods of making aliphatic amines?
halogenoalkanes + excess ammonia
reducing nitriles
what is the problem of excess ammonia and reducing nitriles?
doesnt only produce primary aliphatic amines produces secondary tertiary and quarternary so the yield is lower
mechanism for halogenoalkane + excess ammonia to make aliphatic amines?
lone pair in ammonia attacks C bonded with halogen as it its slightly postive
forces halogen with electron of
ammonia lone pair acts as base and accepts hydrogen of Nh3+ which is positively charged due to to it having 4 bonds
NH3- bonds with negatively charged halogen
2 reaction for the reduction of nitriles to form amines? (catalytic hydrogenation )
nitriles reduced by hydrogen and nickel cataylst
R-CH2-C≡N + 2H2 -> R-CH2-CH2-NH2
conditions high temp and pressure
Nitriles reduced by strong reducing agent e.g LiAlH4
R-CH2-C≡N +4{H} -> R-CH2-CH2-NH2
