Question

Given is mechanism of Beckmann rearrangement.

Which of the following reagent cannot used in Beckmann rearrangement?

• A. $TsOH$
• B. $R-S{O}_{2}Cl$
• C. $B{F}_3$
• D. $Ph-Li$

Answer 1

The correct option is D $Ph-Li$

In Beckmann rearrangement $H_{2}S{O}_4$ can be used. Instead of $H_{2}S{O}_4,A{l}_2{O}_3,TSS{O}_{2}Cl,PC{l}_3,PC{l}_6,P_2{O}_5,TSOH,B{F}_3,R-S{O}_{2}Cl$. All these reagent also give same product as $H^{\oplus }$.
In Beckmann oxime react in presence of Lewis acid or to give amide after rearrangement.
$Ph-Li$ cannot be used as reagent in Beckmann reaction.