Write the reaction of bromine water on glucose.(b) Define – Enantiomers

Answer:

(a) Bromine water, a mild oxidising agent, oxidises the –CHO group of glucose to –COOH, giving gluconic acid:

CHO–(CHOH)₄–CH₂OH + [O] —(Br₂ water)→ COOH–(CHOH)₄–CH₂OH (gluconic acid)

This shows that glucose contains an aldehyde group.

(b) Enantiomers: Stereoisomers which are non-superimposable mirror images of each other are called enantiomers. They have identical physical properties except that they rotate plane-polarised light through equal angles in opposite directions (e.g. D-(+)-glyceraldehyde and L-(−)-glyceraldehyde).