A 1-mole sample of an unknown terminal alkyne with the formula reacts quantitatively with an excess of methylmagnesium bromide () in dry ether. Exactly how many moles of methane gas are liberated duri

Question

A 1-mole sample of an unknown terminal alkyne with the formula $C_5H_8$ reacts quantitatively with an excess of methylmagnesium bromide ($CH_3MgBr$) in dry ether. Exactly how many moles of methane gas are liberated during this acid-base reaction?

Prashant Kotian · Accepted Answer

Correct answer: 1. A terminal alkyne contains exactly one highly acidic hydrogen atom attached to the -hybridized carbon. Methylmagnesium bromide acts as a strong base, abstracting this acidic proton to form methane gas () and the alkynylmagnesium bromide salt. Since there is only one acidic proton per molecule, 1 mole of the terminal alkyne reacts with 1 mole of the Grignard reagent to release 1 mole of methane.

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