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I am doing some Aldol reaction in lab,problem is **basically one of my Aldehyde is converting largely in cannizzaro products.**Please suggest me which base I can use so that I will not get cannizzaro products or get them in very less amount.

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    $\begingroup$ And what is the reaction, exactly? $\endgroup$
    – Raphaël
    Commented Aug 13, 2019 at 18:22

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I suspect that the rogue aldehyde in consideration has highly substituted alpha carbon/s..

Refer https://www.organic-chemistry.org/namedreactions/aldol-addition.shtm for the proper mechanism for aldol addition.

Note that the enolate of the other carbonyl reactant is a nucleophile which adds to the electrophilic carbonyl atom. Naturally, steric hinderance plays a big part in this nucleophilic addition to the aldehyde. Thus, a highly substituted aldehyde shows less tendency towards aldol addition. (Trivia: this same steric interaction is also responsible for the fact that ketones are less reactive towards aldol addition that aldehydes)

Excpetional case: Formaldehye Formaldehyde is the ideal aldehyde for aldol addition (least steric hinderance). But it also has a high tendency to get oxidised to formic acid (Cannizarro product).

Imo, you are carrying out the reaction in a highly basic medium, which will naturally favour cannizzaro in highly substituted aldehydes and formaldehyde. Mildy basic conditions might help.

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