Amines 1

i) ephedrine and adrenaline help are used to increase blood pressure. both have secondary amino group ii) novocain is used as an anaesthetic in dentistry, synthetic amini cpd iii)benadryl is an anti-histaminic drug having tertiary amino group iv)quarternary ammonium salts are used as surfactants v) diazonium salts are intermediates in the preparation of a variety of aromatic compounds including dyes.

Amines can be considered as derivatives of ammonia, obtained by replacement of one, two or all the three hydrogen atoms by alkyl and/or aryl groups. The nitorgen atom is sp3 hybridised and has pyrimidal geometry.

the angle of amines is 107* because of lp-bp repulsion in trimethyl amines the angle is slightly larger due to the repulsion between bulky methyl groups

it can be classified into primary, secondary and tertiary amines. Amines are said to be ‘simple’ when all the alkyl or aryl groups are the same, and ‘mixed’ when they are different.

i) named as alkyl amine. di tri used to indicate more than 1 alkyl group ii) named as alkanamine. locants used to specify position of nh2 group the substituents attached to N directly and indicated with the help of N C6H5-NH2 is called as aniline or benzenamine

The lower aliphatic amines are gases with fishy odour. Primary amines with three or more carbon atoms are liquid and still higher ones are solid. Aniline and other arylamines are usually colourless (brown) but get coloured on storage due to atmospheric oxidation.

Lower aliphatic amines are soluble in water because they can form intermolecular hydrogen bonds with water molecules. However, solubility decreases with increase in molar mass of amines due to increase in size of the hydrophobic alkyl part. Higher amines are essentially insoluble in water.

aniline is insoluble in water due to the large hydrocarbon part which is hydrophobic in nature.

alcohols are more polar than amines and form stronger intermolecular hydrogen bonds with water than amines. This is due the difference of electronegatvitiy of O and N. electronegativity of nitrogen of amine and oxygen of alcohol is 3.0 and 3.5

Primary and secondary amines are engaged in intermolecular association due to hydrogen bonding between nitrogen of one and hydrogen of another molecule. This intermolecular association is more in primary amines than in secondary amines as there are two hydrogen atoms available for hydrogen bond formation in it.

Tertiary amines do not have intermolecular association due to the absence of hydrogen atom,bonded to the nitrogen, available for hydrogen bond formation.

primary> secondary> tertiary

alcohol > 1o > 2o > 3o amine > hydrocarbon