Question

When acetylene is passed into methanol at $160- 200�C$ in the presence of a small amount of potassium methoxide under pressure, the following is formed -

• A. Polyvinyl alcohol
• B. Divinyl ether
• C. Dimethyl ether
• D. Methyl vinyl ether

Answer 1

Answer: (D)

Methyl vinyl ether

Answer 2

When acetylene is passed into methanol at $160-200^�C$ in the presence of a small amount $(1-2\%)$ of potassium methoxide and under pressure just high enough to prevent boiling, methyl vinyl ether is formed.
The mechanism is believed to involve nucleophildic attack in the first step.
\ce{HC\equiv CH + CH3 O^-->C^-H=CH OCH3->[CH_3OH]CH2=} $\underset{\text{Methyl vinyl ether}}{\ce{CHO CH3 + CH3O�}}$