The mercury(II) acetate catalyzed addition of acetic acid to acetylenic alcohols
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The addition reactions of acetic acid to acetylenic alcohols in the presence of mercury(II) acetate have been studied. In this reaction, acetylenic alcohols, when refluxed in acetic acid and catalytic amount of mercury(II) acetate, gave α-acetoxy ketone. ... Tertiary acetylenic alcohols, such as 2-methyl-3-butyn-2-ol, were found to react more rapidly and more completely than secondary or primary acetylenic alcohols, while saturated tertiary alcohol under the same reaction conditions was found to be less reactive than secondary or primary saturated alcohols. 2-Hydroxy-2-methyl-3- butanone, 2-butyn-l-ol, 3-butyn-l-ol, allyl alcohol, 1- hexyne, 2-methoxy-2-methyl-3-butyne were also treated in the same manner. The reactions of 2-methyl-3-butyn-2-ol were also carried out separately in methanol or nitro- ethanol in presence of mercury(II) acetate and trace of p-toluenesulfonic acid. Comparison of the results obtained suggest the neighboring hydroxyl group participate in the formation of the α-acetoxy ketone by attacking the mercurinium complex to form an epoxide ring. Opening this epoxide ring, either by the attack of acetic acid or by rupture to a carbocation, leads to the acetoxy ketone.