Abstract: The present invention describes an improved industrial process for crystallizing out polymorph ‘Form I’ of (+) clopidogrel hydrogen sulphate (also called clopidogrel bisulphate) in) from either a Type-1 solvent or liquid characterized by comprising two or more functional groups or their mixtures thereof; or a Type-II solvent and/or solvent mixture selected from the group of methyl ethyl ketone, cyclopentylmethyl ether, dipropylglycolether, dibutylglycol ether, propylmethyl cellosolve, butylmethylcellosolve, propylethylellosolve, butylethylcellosolve or their cross combinations in a reproducible manner without detectable contamination of polymorph designated as ‘Form II’. The invention also discloses improvements in the preparation of clopidogrel free base and process for recovery and recycling of resolving agent camphor sulphonic acid.

Abstract: The present invention describes an improved industrial process for crystallizing polymorph Form I of (+) clopidogrel hydrogen sulphate (also called clopidogrel bisulphate) in either a Type-I solvent or a Type-II. Type I solvent is an organic solvent containing two or more functional groups with a proviso that at least one functional group is different from the other(s). The Type II solvent is selected from methyl ethyl ketone, cyclopentylmethyl ether, dipropylglycolether, dibutylglycol ether, propylmethyl cellosolve, butylmethylcellosolve, propylethylellosolve, butylethylcellosolve or their cross combinations. The process produces Form I in a reproducible manner without detectable contamination of polymorph designated as Form II.