Question

give reason for following sn1 mechanisms
(NEET 2016)

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Answer 1

Correct ans: D

Order of Sn2 reactions 1° alkly halide >2°alkyl halide >3° > benzyl

Sn1 follows the reverse order

Given substrate is a 1° halide so it will follow SN² mechanism.

SN² reactions are accelerated in aprotic medium.

In the given option ethonol, methanol and H2O are protic medium as it can release protons where DMF don't

So, the since given rection SN² which is accelerated by non-protic medium the correct answer will be DMF.

Note:

SN² involves no carbocation formation where as SN does.

SN1 is accelerated by protic medium like h2o,ethanol etc.