JEE Main · 2019 · 08 Apr 2019 · Shift 1 · Compounds Containing Nitrogen

The Gabriel phthalimide synthesis builds a primary amine by letting the phthalimide anion displace halide from an alkyl halide in an ${\mathrm{S}}_{\mathrm{N}}2$ step, the amine being freed afterwards by hydrolysis. Because that key step is ${\mathrm{S}}_{\mathrm{N}}2$, it works only on primary or methyl halides: tertiary halides eliminate instead and aryl halides do not react, so triethylamine and t-butylamine are ruled out and the hindered neopentyl halide reacts only sluggishly. The straight-chain primary case, n-butylamine, is the one cleanly made this way.