Amino acids, amides and chirality

α Amino acid

An α amino acid has the NH₂ and COOH group attached to the same carbon

What happens at a certain pH to amino acids

They act as zwitterions, this is where the acidic COOH group donates a proton to the the basic NH₂ group

Why are amines bases

It uses the lone pair on the N to accept a proton

Why are Carboxylic acids, acids?

They donate protons

Reaction of α amino acids as an acid

• The COOH reacts with a base, OH^-, and the COOH group loses a H⁺ ion

Reaction of α amino acids as base

• The NH₂ reacts with an acid, H⁺, and the NH₂ group gains a H⁺ ion

Organic reactions of amino acids

Amino acid + Alcohol → Ester + Water

Amides

• Primary amide - has functional group CONH₂

• Secondary amide - has functional group CONHR

• Named with prefix-amide

Synthesis of Amides

• They’re made by reacting ammonia or amines with acyl chlorides

Hydrolysis of amides - acid

Amide + water + HCl → Carboxylic acid + NH₄Cl

Hydrolysis of amides - alkaline

Amide + NaOH → Carboxylate Salt + Ammonia

Chirality

Stereoisomerism compounds with the same structural formula but different arrangement of atom in space

A chiral carbon (centre)

Has 4 different groups attached

Optical Isomerism ( Enantiomers)

Optical isomers are stereoisomers that are non-superimposable mirror images about a chiral centre