Talk:Claisen condensation: Difference between revisions

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Inaccurate/Oversimplified Mechanism

The mechanism image is not quite correct; the product is not protonated until the addition of acid. The product is more acidic than the starting material, so the regenerated alkoxide would deprotonate the product in preference to the starting material. The deprotonation is mechanistically important as it drives the reaction thermodynamically.

Agreed, the mechanism is not correct but it appears that it is taught this way a lot, all of the University/.edu web pages I looked through on a quick google search seemed to teach this oversimplified mechanism. I've found the complete/accurate mechanism in Solomons Organic Chemistry 6th edn from page 860 onwards. Meltyman (talk) 13:37, 14 December 2008 (UTC)[reply]

I think the mechanism of the very similar Aldol condensation gives a good impression how it really works.--Stone (talk) 14:17, 14 December 2008 (UTC)[reply]

For anyone who wants to work on it, the mechanism is here. It has the beta-keto ester anion in the second last step, which is then protonated to the neutral molecule. Meltyman (talk) 17:49, 14 December 2008 (UTC)[reply]

...The problem was dealt with by the User:Thezookeeper, but then this section was deleted from the talk page which shouldn't be done. I restored this section to the talk page. Meltyman (talk) 19:08, 21 January 2009 (UTC)[reply]

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 {{chemistry}}
+== Inaccurate/Oversimplified Mechanism ==
+The mechanism image is not quite correct; the product is not protonated until the addition of acid. The product is more acidic than the starting material, so the regenerated alkoxide would deprotonate the product in preference to the starting material. The deprotonation is mechanistically important as it drives the reaction thermodynamically.
+Agreed, the mechanism is not correct but it appears that it is taught this way a lot, all of the University/.edu web pages I looked through on a quick google search seemed to teach this oversimplified mechanism. I've found the complete/accurate mechanism in Solomons Organic Chemistry 6th edn from page 860 onwards.
+[[User:Meltyman|Meltyman]] ([[User talk:Meltyman|talk]]) 13:37, 14 December 2008 (UTC)
+:I think the mechanism of the very similar [[Aldol condensation]] gives a good impression how it really works.--[[User:Stone|Stone]] ([[User talk:Stone|talk]]) 14:17, 14 December 2008 (UTC)
+For anyone who wants to work on it, the mechanism is [http://books.google.ie/books?id=yVPcSIn5xjAC&pg=PT519&lpg=PT519&dq=claisen+condensation+organic+chemistry+demystified&source=bl&ots=rsTG0IyNpv&sig=Dg1W7g859PmjKvn5e2hHdMz5xVA&hl=en&sa=X&oi=book_result&resnum=1&ct=result here].
+It has the beta-keto ester anion in the second last step, which is then protonated to the neutral molecule.
+[[User:Meltyman|Meltyman]] ([[User talk:Meltyman|talk]]) 17:49, 14 December 2008 (UTC)
+...The problem was dealt with by the User:Thezookeeper, but then this section was deleted from the talk page [http://en.wikipedia.org/wiki/Wikipedia:Talk_page_guidelines#When_pages_get_too_long which shouldn't be done.] I restored this section to the talk page.
+[[User:Meltyman|Meltyman]] ([[User talk:Meltyman|talk]]) 19:08, 21 January 2009 (UTC)