mcq.
question no. 1
p-nitrocetanilide is almost insoluble in ethanol. Wheather the statement is
a. false
c.not assigned
d. cannot possible
b. true
Answers
Nitration of acetanilide proceeds smoothly to give p- nitroacetanilide. When purified well, the product will have light yellow color & it has a melting point close to 214-216 oC. Trouble is that traces of acid left will hydrolyze it into p-nitroaniline which has deep yellow to yellow-orange color (this compound has melting point of 146 -149 °C) and it smells like ammonia. Unfortunately, p-nitroaniline is difficult to remove from p-nitroacetanilide by crystallization. That is why I said “close to” above; I mean one will not get the theoretical melting point (since there is an impurity) but a lower one.
By the way, if p-nitroaniline is sought for preparation, we cannot nitrate aniline easily since the acid will go directly to the amino group & convert aniline to anilinium salt. The anilinium group is meta-directing if nitration is to proceed!
Explanation:
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