Complex sentence: In 1986, its pharmaceutical business was spun off as Celgene and in 1987, Celanese Corporation was acquired by Hoechst and merged with its American subsidiary, American Hoechst, to form Hoechst Celanese Corporation.
Split into simpler sentences: In 1986, its pharmaceutical business was spun off as Celgene. In 1987, Celanese Corporation is acquired by Hoechst and merged with its American subsidiary, American Hoechst, to form Hoechst Celanese Corporation.