Reaction Mechanism In Organic Chemistry By - Mukherjee And Singh

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It sounds like you're looking for a (or a distinctive characteristic) of the book Reaction Mechanism In Organic Chemistry by S.M. Mukherjee and S.P. Singh (often published by Macmillan or similar). Since you asked for "a feature" (singular), here

Exceptionally detailed, step-by-step arrow-pushing mechanisms for mixed competitive reactions (e.g., substitution vs. elimination). substitution vs. elimination).