Inversion, retention and racemization: Whenever in a chemical reaction, a bond is broken at the chiral carbon atom, there are the three possibilities. For example, consider the replacement of a group x by y in the following reaction:

If (A) is the only compound obtained, the process is called as stereospecific retention of configuration. If (B) is the only compound obtained, the process is called as stereospecific inversion of configuration. If a 50:50 (equal) mixture of A and B is obtained, the process is called as a non – stereospecific reaction or racemisation and the product is optically inactive, as one isomer will rotate the plane of polarized light in one direction and the other will rotate in opposite direction but to the same extent.