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12: Acyl substitution reactions

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    A complete PDF version of Organic Chemistry With a Biological Emphasis is available here as a free download.

    In chapter 11, we learned about the chemistry of aldehydes and ketones. We saw several variations on a single overarching theme – the attack by a nucleophile on the electrophilic carbonyl carbon.

    image002.png

    In this chapter, we will see many variations of a reaction type known as nucleophilic acyl substitution, the substrates for which are not aldehydes and ketones but carboxylic acid derivatives, such as acyl phosphates, thioesters, esters, and amides.

    image004.png

    In nucleophilic acyl substitutions, the first step is again the attack of a nucleophile on an electrophilic carbonyl carbon. Because the carbonyl carbon is bonded directly to a leaving group, however, the tetrahedral intermediate quickly collapses, expelling the leaving group (X in the figure below) and re-forming the trigonal planar, sp2-hybridized carbonyl.

    image006.png

    It is difficult to overemphasize how widespread nucleophilic acyl substitution reactions are in biochemical pathways: you will see them again and again when you take a course in biochemistry. As we shall soon see, these reactions are especially important in the metabolism of lipids (fats and oils) and in the formation and breakdown of peptide bonds in proteins.

     
     
    Organic Chemistry With a Biological Emphasis by Tim Soderberg (University of Minnesota, Morris)

    This page titled 12: Acyl substitution reactions is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.


    This page titled 12: Acyl substitution reactions is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Tim Soderberg via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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