4 - amino ]- 4 - pyrimidinyl ] oxy ]- 3 , 5 - dimethyl - benzonitrile is a key intermediate for the preparation of etravirine . the present invention provides a process for preparation of 4 - amino ]- 4 - pyrimidinyl ] oxy ]- 3 , 5 - dimethylbenzonitrile . the present invention also provides a novel process for the preparation of etravirine crystalline form i . the present invention further provides novel crystalline forms of etravirine , processes for their preparation and pharmaceutical compositions comprising them .