Organic Lab Reactions 101

Organic Lab Reactions 101 - the same scheme, with...

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96 THE CANNIZZARO REACTION these enzyme and catalytic reactions than between either of them and the true Cannizzaro reaction. MECHANISM OF THE REACTION A number of mechanisms have been suggested for the Cannizzaro reaction. 13 - 14 > 1B One mechanism, based upon a proposal by Lock, 16 who patterned his suggestion after those put forward by Grignard and Fluchaire 16 and by Fredenhagen and Bonhoeffer, 17 is the following. o- RCHO + OH" ^ RCH OH o- RCH + RCHO ;=± RCHOCHR \ I I OH OH O- OH RCHOCHR -> RCHJSOCR + 0H~ ?i RCH 2 0CR OH O- 0 0 - OH RCH 2 0CR -* RCH 2 0H + RCOs" o- This mechanism adequately coordinates the well-known variations of base-induced dismutations of aldehydes into a general picture and makes it unnecessary to suppose that different bases act in different ways. The formation of esters when an aldehyde is treated with an alkoxide follows
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Unformatted text preview: the same scheme, with OR"" in place of 0H~, and takes into account the ester interchanges which have been observed to occur. The transforma-tion of benzaldehyde into benzamide and benzyl alcohol by the action of sodamide 18 proceeds analogously, amide-ester interchange brought about by the amide ion being the last step. 13 Hammett, "Physical Organic Chemistry," p. 350, McGraw-Hill, New York, 1940. 14 Eistert, "Tautomerie und Mesomerie," p. 116, Enke, Stuttgart, 1938. 16 Eitel and Lock, Monatsh., 72, 392 (1939). 16 Grignard and Fluchaire, Ann. chim., [10] 9, 5 (1928). 17 Fredenhagen and Bonhoeffer, Z. physik. Chem., A181, 379 (1938). 18 Haller and Bauer, Ann. chim. phys. 16, 145 (1909)....
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