6.2.2 Amino Acids, Amides and Chirality

Question 1

Amino acids esterification

Answer 1

RCH(NH2)COOH + R’-OH → RCH(N+H3)COOR’ + H2O

Conditions: con. H2SO4/HCl

Question 2

Acid hydrolysis of polyamides

Answer 2

RCH(NH2)CONHCH(R’)COOH → RCH(N+H3)COOH + H3N+CH(R’)COOH
Reagents: dilute HCl
Conditions: heating

Question 3

Alkali hydrolysis of polyamides

Answer 3

RCH(NH2)CONHCH(R’)COOH → RCH(NH2)COO- + H2NCH(R’)COO-
Reagents: Excess NaOH
Conditions: heating

Question 4

Optical isomerism

Answer 4

Two compounds that are optical isomers of each other are called enantiomers

• rotate plane polarised light in different directions (One enantiomer rotates it in one direction, other enantiomer rotates it by same amount in opposite direction)

Question 5

Zwitterions

Answer 5

Ion containing both a positive and negative charge

• isoelectric point is the pH at which the zwitterion is formed
  pH < IP = RCH(N+H3)COOH
  pH > IP = RCH(NH2)COO-

Question 6

Amino acids amidification

Answer 6

H2NRCH(NH2)COOH + 2R’COCl → NHRCH(NHR’)COOH