# Why does alkyl rearrangement happen in the Hofmann rearrangement?

In the mechanism of Hofmann rearrangement, one step involves migration of an R−group from carbon to nitrogen.

This reaction proceeds even if the migratory aptitude of the R-group is poor (like in the case of ethanamide). What motivates the migration of the R-group and makes the reaction proceed?

• Why do you say that migratory aptitude is poor? Poor relative to what? – Zhe Sep 21 '17 at 18:51

I would not be surprised to see vastly different reaction times between compounds, depending on whether the $\ce{R}$ group easily migrates or not.