[Firehchicken]

So the question is : Which of the following mechanisms are acceptable for the reaction on the right to occur.

Answer to this question is choice C). I do not understand why.

I know that mechanism C is unacceptable cuz u cant have the electrons flowing to the nucleophile.

However, I cant see why mechanism A is incorrect. Likewise, I also cant see why Mechanisms B and D are correct.

What's the big deal with electrons moving around the oxygen??

[Babcock_Hall]

With respect to your last question, it may be that this motion is intended to portray an addition-elimination mechanism, meaning a mechanism in which the nucleophile adds in the first step and the leaving group departs in a subsequent step.  With respect to any of these mechanisms, I would give some thought to the question of whether or not a good leaving group is present.

[Firehchicken]

With respect to your last question, it may be that this motion is intended to portray an addition-elimination mechanism, meaning a mechanism in which the nucleophile adds in the first step and the leaving group departs in a subsequent step.  With respect to any of these mechanisms, I would give some thought to the question of whether or not a good leaving group is present.

I see. NH2 being a poor leaving group

[sjb]

Have you had any other thoughts why the others are incorrect? Hint - what does the arrow mean?

As to why the tetrahedral intermediate is implicated - I believe in some cases it has been isolated.