Q. The order of reactivity of phenyl magnesium bromide (PhMgBr) with the following compounds: (I) CH₃CHO, (II) (CH₃)₂C=O and (III) Ph₂C=O is
A) I > III > II
B) I > II > III
C) III > II > I
D) II > I > III
Explanation
[Solution from source] Nucleophilic addition of PhMgBr gets slower as electron-donating and bulky groups around the carbonyl carbon increase. Acetaldehyde (one H, one CH₃) is most reactive, acetone (two CH₃) is next, and benzophenone (two bulky phenyls with resonance) is least reactive: I > II > III. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.