What is the product?

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1 Answer
Ernest Z.
May 14, 2018

The product is 4-methylpentane-1,4-diol.

Explanation:

Your substrate is a lactone (a cyclic ester).

Grignard reagents react with esters to form tertiary alcohols.

#"R"_1"CO-OR"_2 + stackrelcolor(blue)(1. "2R"_3"MgX"color(white)(mm))(→) "R"_1("R"_3)_2"C-OH" + "R"_2"-OH"#
#color(white)(mmmmmmml)stackrelcolor(blue)("2. NH"_4"Cl(aq)"#

The mechanism for the reaction of #"methylmagnesium bromide"# with #"γ-butyrolactone"# is:

Mechanism

The steps are

  1. The Grignard reagent adds a methyl group to the base of the carbonyl
  2. The carbonyl group regenerates with loss of the ester alkyl group
  3. The Grignard reagent adds a methyl group to the new carbonyl
  4. The acidic ammonium chloride solution protonates the alkoxide ions
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