Question

6. Which experimental evidence would not support the SN2 mechanism for the reaction between (S)-2-bromooctane and sodium acetylide (aka ethynylsodium)? and is it the answer
(A) Only (S)-3-methyl-1-nonyne is observed as a product.
(B) The reaction rate decreases tenfold when the concentration of bromooctane is reduced from 1.0 M to 0.1 M
(C) The reaction rate doubles when the concentration of sodum acetylide is doubled.
(D) The rate of reaction is increased by switching from sodium to potassium acetylide.

Answer 1

This reaction proceeds via SN2 mechanism.

In this Inversion of stereochemistry of the product observed upon substitution of the nucelophile. So; the product stereochemistry will be (R) [not (S)].

So; the statement which not give evidence for SN2 substitution is

(A) Only (S)-3-methyl-1-nonyne is observed as a product.

= Na ethynylsodium (S)-2-bromooctane SN2 substitution (R)-3-methyl-1-nonyne

= Na ethynylsodium (S)-2-bromooctane SN2 substitution (R)-3-methyl-1-nonyne