Process for the preparation of O-desmethylvenlafaxine succinate polymorphic forms

1. A process for the preparation of O-Desmethylvenlafaxine succinate Form-II, comprising the steps of:

a) dissolving O-Desmethylvenlafaxine base in a solvent,

b) heating the reaction mass to reflux,

c) adding succinic acid,

d) cooling the reaction mass, and

e) isolating O-Desmethylvenlafaxine succinate Form-II.

2. The process according to claim 1 , wherein the solvent is selected from acetonitrile, chloroform, ethyl acetate, isopropyl alcohol, n-propanol, n-butanol, cyclohexane or mixture thereof.

3. The process according to claim 1 , wherein the succinic acid is selected from solid succinic acid or succinic acid solution.

4. The process according to claim 1 , wherein the O-Desmethylvenlafaxine base is a solid or a liquid solution.