4-Acetylbiphenyl is involved in the study of inactivation of 7-ethoxy-4-trifluoromethylcoumarin ortho-deethylase activity by various arylalkynes. Further, it is used in the preparation of Schiffs base.4-Acetylbiphenyl was used to study the inactivation of 7-ethoxy-4-trifluoromethylcoumarin O-deethylase activity by various arylalkynes. It may be used in the synthesis of Schiffs base.