[PDF] ac2o dmap mechanism

This mechanism involves the formation of the acylpyridinium ion pair from the reaction of the DMAP catalyst with the acyl donor; later, the alcohol reacting with the acylated catalyst in the rate-determining second step and forming the ester product with the protonated catalyst.
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  • How does DMAP work as a catalyst?

    A better explanation for DMAP being such an effective catalyst is that it reacts with acid chlorides, such as 12, to form high concentrations of N?acylpyridinium salts (eq 7). These salts are better able to transfer an acyl group to a nucleophile than is the acid chloride itself.

  • What does DMAP do in a reaction?

    DMAP is an acyl transfer reagent that reacts regioselectively at the less hindered carbonyl site: DMAP is a stronger nucleophile than the alcohol. The newly formed intermediate is less hindered, the acyl group is still polarized and DMAP is a good leaving group, all of which enable a fast reaction with the alcohol.

  • What is the mechanism of ethanol and acetic anhydride?

    The reaction between acetic anhydride and ethanol requires heating in the absence of catalysts. Anhydrides composed of two different acids are called mixed anhydrides. The mechanism involves four steps-nucleophilic attack by alcohol, deprotonation by pyridine, leaving group removal and protonation of carboxylate.
  • Because of its basicity, DMAP is a useful nucleophilic catalyst for a variety of reactions such as esterifications with anhydrides, the Baylis-Hillman reaction, hydrosilylations, tritylation, the Steglich rearrangement, Staudinger synthesis of ?-lactams and many more.
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