Optical activity

Question

1. How exactly does a Pure enantiomeric acid + Optically active alcohol having chiral carbons result in a product which is optically active?

2. How does a racemic acid + optically active alcohol having chiral carbon atom result in a diastereomic mixture as the product?

Please explain with examples.

Answer 1

By enatiomeric acid and optically active alcohol reaction, you are likely referring to Fischer Esterification.

1) The carboxylic acid is optically active if it has a chiral center. The alcohol is optically active, so it has a chiral center. So if you form the ester R^*(O)OR'^** you now have molecule with two chiral centers, so it will certainly be optically active.

2) In the racemic acid reaction case there are at least two different types of chiral centers of the acid to choose from to form

(A^*(O)OR'^**) and (B^*(O)OR'^**),

where A and B are the at least two different types of arrangements around the chiral center. I say at least two types because there could be more than one chiral center I guess for starters.