NEET UG 2023 — Chemistry Organic Chemistry

Lithium aluminium hydride is a strong reducing agent. It converts amides, cyanides and isocyanides to amines.

$${\mathrm{CH}}_{3}{\mathrm{CONH}}_{2}\rightarrow _{(\mathrm{ii}){H}_{3}{O}^{+}}^{(i){\mathrm{LiAlH}}_{4}}{\mathrm{CH}}_{3}{\mathrm{CH}}_{2}{\mathrm{NH}}_{2}(\mathrm{primary}\mathrm{amine})$$CH3​CONH2​→(ii)H3​O+(i)LiAlH4​​CH3​CH2​NH2​(primaryamine)

$${\mathrm{CH}}_{3}\mathrm{CN}\rightarrow _{(\mathrm{ii}){H}_{3}{O}^{+}}^{(i){\mathrm{LiAlH}}_{4}}{\mathrm{CH}}_{3}{\mathrm{CH}}_{2}{\mathrm{NH}}_{2}(\mathrm{Primary}\mathrm{amine})$$CH3​CN→(ii)H3​O+(i)LiAlH4​​CH3​CH2​NH2​(Primaryamine)

$${\mathrm{CH}}_{3}\mathrm{NC}\rightarrow _{(\mathrm{ii}){H}_{3}{O}^{+}}^{(i){\mathrm{LiAlH}}_{4}}{\mathrm{CH}}_{3}{\mathrm{NHCH}}_{3}(\mathrm{Secondary}\mathrm{amine})$$CH3​NC→(ii)H3​O+(i)LiAlH4​​CH3​NHCH3​(Secondaryamine)

In Hoffmann bromamide reaction, primary amides converts to primary amines with loss of one carbon.

$${\mathrm{CH}}_{3}{\mathrm{CONH}}_{2}\overset{{\mathrm{Br}}_{2}/\mathrm{KOH}}{\rightarrow }{\mathrm{CH}}_{3}{\mathrm{NH}}_{2}$$CH3​CONH2​→Br2​/KOHCH3​NH2​