$(B)$ Hoffmann bromamide reaction $\rightarrow$ known reaction of isocynates

$R - CO - NH _{2}+ X _{2}+4 NaOH \rightarrow R - NH _{2}+$

$2 NaX + Na _{2} CO _{3}+2 H _{2} O$

Intermediate : $R - N = C = O$ (isocyanate)

$(C)$ Carbylamine reaction $\rightarrow$ Test for primary amine

$R - NH _{2}$ or $Ar - NH _{2}+ CHCl _{3}+3 KOH \rightarrow RNC$ or $Ar - NC +3 KCl +3 H _{2} O$

$(D)$ Hoffmann orientation $\rightarrow$ Anti saytzeff (Formation of less substituted alkene as major product)