Reactions of carbonyl compounds in the presence of phase-transition catalysts. 4. Study of the reaction of acetoacetic ester with 1-chloro-3-methyl-2-butene in the presence of various alkaline agents

Abstract

1. The conditions for the selective formation of prenylacetoacetic ester (I) in the presence of a 50% aqueous K2CO3 solution and triethylbenzylammonium chloride (TEBA chloride) and of diprenylacetoacetic ester (II) in the presence of a 50% aqueous KOH solution and TEBA chloride were found. The effect of the concentration of aqueous alkali on the direction of the reaction was studied. 2. The difference in the condensing activities of KOH and K2CO3 is due to the large difference in the acid-base equilibrium constants of their reactions with acetoacetic ester (AAE). The effect of the concentrations of aqueous solutions of KOH in the presence of TEBA chloride on the rate of monoalkylation was studied. 3. The kinetic basicity of a 50% aqueous solution of K2CO3 in the presence of a phase-transition catalyst was estimated, and it was assumed that the condensing activity of this system is determined exclusively by the catalytic action of TEBA hydroxide. 4. A scheme for the monoalkylation of AAE that presupposes several pathways is discussed. In the presence of a 50% aqueous solution of KOH and TEBA chloride the reaction proceeds through the potassium or triethylbenzylammonium derivative of AAE with KOH and the TEBA base, respectively. 5. Dialkylation proceeds only in the presence of concentrated aqueous solutions or solid KOH; this is associated with the difference in the acidities of AAE and ester I. 6. An induction period that does not depend on the presence of TEBA in the system and is due to the formation of water as a result of the reaction is observed during the formation of 2-methylhept-2-en-6-one in the presence of solid KOH.