Question

Question: Several additional amine synthesies are effectively limited to making primry amines. The reduction of azides and nitro compounds and the Gabriel synthesis leave the carbon chain unchanged. Formation and reduction of a nitrile adds one carbon atom. Show how these amines syntheses can be used for the following conversions.
(a) allyI bromide → allylamine
(b) ethylbenzene → p-ethylaniline
(c) 1-bromo- 3-phenylheptane → 3-phenylheptan- 1-amine
(d) 1 -bromo- 3-phenylheptane → 4-phenyloctan- 1-anime

Short answer

Synthesis of primary amines by alkylation of the potassium salt of phthalimide, followed by displacement of the amine by hydrazine.

Step-by-step solution

Gabriel synthesis

Synthesis of primary amines by alkylation of the potassium salt of phthalimide, followed by displacement of the amine by hydrazine.

Synthetic methodology

(a) Phthalimide combines with allyl bromide to give 2-allylisoindoline-1,3-dione, which on further treatment with hydrazine gives the products as allylamine and phthalimide hydrazine.

reaction a
(b) Ethylbenzene when treated with nitric acid in presence of sulfuric acid gives the initial product as 1-ethyl-4-nitrobenzene, which on further reduction with Sn/HCl gives the final product as 4-ethylaniline or p-ethylaniline.

reaction b
(c) Phthalimide combines with 1-bromo-3-phenylheptane to give 2-(3-phenylhexyl)isoindoline-1,3-dione, which on further treatment with hydrazine gives the products as 3-phenyl-heptan-1-amine and phthalimide hydrazine.

reaction c
(d) 1-bromo-3-phenylheptane reacts with potassium cyanide to give the initial product as 4-phenyloctanenitrile, which on further reduction with lithium aluminum hydride gives the final product as 4-phenyloctan-1-amine.


reaction d