| Autor: |
Yufit, S. S., Esikova, I. A. |
| Zdroj: |
Russian Chemical Bulletin; January 1983, Vol. 32 Issue: 1 p36-41, 6p |
| Abstrakt: |
Conclusions 1.The interaction of acetoacetic ester with 1-chloro-3-methyl-2-butene in the presence of solid K2CO3 and catalytic quantities of benzyltriethylammonium chloride leads to selective formation of the monoalkylated product, with a high yield. In order to obtain the dialkylated product, it is necessary to use a stronger deprotonating agent such as Cs2CO3.2.The reaction kinetics in the alkylation of acetoacetic ester on solid carbonates are determined by the presence of a limiting stage — the deprotonation of the substrate. The reaction is first-order with respect to acetoacetic ester and zero-order with respect to 1-chloro-3-methyl-2-butene. The alkylation reaction rate does not depend on the quantity of catalyst QX that is added, nor on its structure and lipophilicity.3.The deprotonation of acetoacetic ester proceeds on the surface of the solid carbonate and is described by the equation of an irreversible first-order reaction. There is no transfer of CO32- to the organic phase, and hence no homogeneous deprotonation. The deprotonation stops after the active centers have been used up and the surface of the carbonate crystal lattice has become deactivated as a result of bicarbonate formation.4.The role of the catalyst comes down to transfer of bicarbonate ion from the crystal surface into the bulk organic phase, leading to renewal of the carbonate surface; this increases the conversion of acetoacetic ester. The catalyst has no effect on the deprotonation rate. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
Full text from SpringerLink