6.2.2 Amino acids and optical isomerism

Question 1

Structure of alpha amino acids

Answer 1

• 2 functional groups attached to the same carbon atom known as the alpha carbon
• NH2 amino (amine) group and -COOH carboxyl group
• also with a H and R group attached

Question 2

Why is a molecule not an alpha amino acid

Answer 2

• NH2 not attached to the same carbon as -COOH

Question 3

What does amphoteric mean?

Answer 3

a molecule can react as both an acid and a base

• the acid part is the -COOH (H+ donator)
• the base part is the -NH2 (H+ acceptor)

Question 4

Stereoisomer definition

Answer 4

molecules with the same structural formula but a different arrangement of atoms in space
can be E/Z or optical

Question 5

E/Z isomers definition

Answer 5

• the molecule must contain a C=C bond which prevents rotation of the groups attached to each carbon
• each C in the C=C bond much have 2 different groups attached to it

Question 6

Optical isomers definition

Answer 6

• molecules which are non super imposable mirror images of each other
• the molecule must contain a chiral carbon - C with 4 different groups attached directly to it
• C=O bond can’t be chiral (only 3 bonds)
• chiral carbon can be described as asymmetric
• optical isomer also called enantiomers