JEE Main · 2013 · 07 Apr 2013 · Offline · Biomolecules

A compound with molecular mass 180 is acylated with

CH_{3} COCl

to get a compound with molecular mass 390. The number of amino groups present per molecule of the former compound is:

(A)5✓ Correct
(B)4
(C)6
(D)2

Answer: (A)

Solution

Each acetylation with

CH X_{3} COCl

caps one

- NH X_{2}

group and, after the loss of

HCl

, adds a net

CH X_{3} CO

minus one hydrogen, a mass gain of

42

per group. The molecular mass climbs from

180

390

, a rise of

210

, so the number of amino groups is

\frac{210}{42} = 5

JEE Main · 2013 · 07 Apr 2013 · Offline · Single correct option

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