What is the name of the compound #CH_3CH_2S(CH_3)_2# and How does the following reaction happen?

Question

#CH_3CH_2S(CH_3)_2 + C_2H_5ONa ->CH_3 CH_2OC_2H_5 + H_2C=CH_2#
Where, substitution = #88%# and elimination = #12%# . The reaction takes place in presence of ethanol.

EDIT: Added missing product: #"S"("CH"_3)_2#
- Truong-Son

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Answer 1 · 2018-02-22T13:53:30

Here's what I get.

The nucleophile/base is ethoxide ion, #"CH"_3"CH"_2"O"^"-"#.

The substrate is the ethyldimethylsulfonium ion, #"CH"_3"CH"_2stackrelcolor(blue)("+")("S")("CH"_3)_2#

The positive charge on the #"S"# atom makes the dimethylsulfonium ion an excellent leaving group.

The #S"_text(N)2# displacement reaction

The ethoxide acts as a nucleophile and attacks the α-carbon.

SN2

The #"E2"# reaction

The ethoxide acts as a base and attacks the β hydrogen