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Khengchat Ng

cyclohexanone with triethyl orthoformate

David Ford  Follow
Acid catalyzed reactions involving enolization of ketones are more difficult. The loss of an alpha hydrogen is probably kinetically less favored than loss from the oxygen. However, if ethanol is present, it can add to the protonated ketone. If you know this chemistry, you know this is an intermediate in ketal formation. The by-product of a ketal is water. Water can react with an ortho ester to give an ester plus ethanol

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Bill Burniece  Follow
Is there water in this reaction mixture?

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Courtney Villeda  Follow
triethylorthoformate will decompose in acidic aqueous media.

I think that if you waited until the β addition to the carbonyl was complete, and the triethylorthoformate consumed to add the water, you will create a new product

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David Sandbrook  Follow
The question didn't say there wasn't any water so I (optimistically) hoped there was.

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Bill Bigos  Follow
Quote from:
The question didn't say there wasn't any water so I (optimistically) hoped there was.

I think you have the correct answer if there is no water in the reaction mixture.

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David Farmer  Follow
Quote from:
Thank you for your reply.
My mechanism does use water though, should I use something else instead of the water molecule? Or just leave the reaction at the point when I use the water?

if there is no water in there, use ethanol to remove protons.

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Allison Kosters  Follow
Thank you for your reply. I checked the question again and it doesn't mention water being present.

Attempt 2: see below.

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David Byrden  Follow
The difficulty with writing this mechanism is in forming ethanol. Once that is done, you might expect a ketone plus ethanol with acid can form a ketal. You might also expect that the water by-product would keep the reaction from going to completion. However, that water can react with the ortho ester. I suggest you try again.

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David Plantz  Follow
Thank you for your reply.
My mechanism does use water though, should I use something else instead of the water molecule? Or just leave the reaction at the point when I use the water?

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