Alkynes

[jdoc04]

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H2SO4 & HgSo4/H2O yields a carbonyl when reacted with an alkyne.

Which carbon get the carbonyl?

C--C--C=--C--C

3 carbons on the left vs. 2 on the right?

and what about terminal alkynes? ketone or aldehyde?

 

[Flipper405]

H2SO4 & HgSo4/H2O yields a carbonyl when reacted with an alkyne.

Which carbon get the carbonyl?

C--C--C=--C--C

3 carbons on the left vs. 2 on the right?

and what about terminal alkynes? ketone or aldehyde?

Both carbons will get a carbonyl; two products will be formed.

If it was a terminal alkyne, a ketone would form because the oxymercuration would preferentially add the hydroxyl group to the internal carbon per Markovnikov's rule.
Hydroboration would be required to form the aldehyde.