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[Goala]

Hi guys:

I was wondering how I could form a ketene from a terminal alkyne?

Let's say I have a strong base like nBuLi and a terminal alkyne, how can I then make a ketene. I tried to think about it, but wasn't able to come up with an answer.

Hope someone can enlighten me

[discodermolide]

Are you sure you mean ketene? Ketene is R'R?C=C=O.
Treating a terminal alkyne with a strong base will give some allene -C=C=C-
Normally a strong base and a terminal alkyne gives the metal salt.
Ketenes: http://en.wikipedia.org/wiki/Ketene

Allenes: http://en.wikipedia.org/wiki/Allene

[Goala]

Are you sure you mean ketene? Ketene is R'R?C=C=O.
Treating a terminal alkyne with a strong base will give some allene -C=C=C-
Normally a strong base and a terminal alkyne gives the metal salt.
Ketenes: http://en.wikipedia.org/wiki/Ketene

Allenes: http://en.wikipedia.org/wiki/Allene

Well, I'd like to treat my terminal alkyne with a strong base, then treat it with sulfur (S8). The goal would be to form a ketene with the O being an S.

[discodermolide]

So you want to make a thioketene. These are not very stable and will polymerise.
Are you following a literature reference, because I don't think this will work.

[Goala]

So you want to make a thioketene. These are not very stable and will polymerise.
Are you following a literature reference, because I don't think this will work.

No, I am not.

I was just thinking about how the mechanism of an alkyne reacting with a strong base then sulfur would vaguely look like to form the corresponding thioketene.

I thought a long time while scribbling down ideas on my piece of paper but couldn't come up with anything!

[discodermolide]

Well I'm sorry to say it makes no sense to me as well.
This is not the way to make ketenes or thioketenes.
Perhaps someone else knows more.