Heterogeneous Catalytic Synthesis of Zingerone and Dehydrozingerone
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rogeneous Catalytic Synthesis of Zingerone and Dehydrozingerone P. A. Chistyakovaa, *, A. V. Chistyakova, and M. V. Tsodikova aTopchiev
Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, 119071 Russia *e-mail: [email protected] Received March 26, 2020; revised May 5, 2020; accepted May 12, 2020
Abstract—Results of a single-stage heterogeneous catalytic synthesis of zingerone and dehydrozingerone have been described. The prospects of the proposed approach have been shown; the main kinetic laws governing the reaction have been revealed. Optimum conditions for zingerone and dehydrozingerone synthesis providing a yield of the target products of 45.8 and 76.2%, respectively, have been found. Keywords: heterogeneous catalysis, copper, dehydrozingerone, zingerone DOI: 10.1134/S0965544120090066
Zingerone and dehydrozingerone are biologically active substances constituting ginger root [1]. These substances are commonly used in the food industry (as flavorings and conserving agents [2]) and the pharmaceutical industry: dehydrozingerone is used as an active component of anticonvulsants, an antioxidant, and an antimutagenic agent [3], while zingerone is an antioxidant and an antiinflammatory agent and exhibits activity in the suppression of enterotoxins (Escherichia coli) that cause diarrhea [4, 5] (this type of diar-
rhea is the main cause of infant mortality in developing countries [6]). Zingerone and dehydrozingerone were first isolated from ginger root by Japanese chemist Hiroshi Nomura in 1917 [7]. In addition, Nomura has developed a synthetic method for zingerone synthesis by the hydrogenation of dehydrozingerone derived by the condensation of acetone and vanillin in the presence of alkalis (Scheme 1).
OH
OH O
O
CH3 +
OH
OH
H3 C
CH3
NaOH
CH3
O +H2
CH3
−H2O
O
CH3
O Dehydrozingerone Scheme 1. Two-stage synthesis of zingerone.
Zingerone is still [8] produced by the two-stage method proposed by Nomura with the use of alkalis, which significantly increases the amount of waste and the cost of production [9]. Currently, attempts are being made to search for effective heterogeneous catalysts for the production of dehydrozingerone by the condensation of acetone with vanillin. A promising catalyst for the process is hydrotalcite, in the presence of which the dehydrozingerone yield achieves 88% within 4 h of the reaction [3]. It was previously found that primary alcohols can undergo heterogeneous catalytic cross-condensation with secondary alcohols [10]. This approach can be
CH3 O Zingerone
used to synthesize zingerone from vanillin and isopropanol in a single stage. A single-stage synthesis in the presence of supported catalysts will make it possible to exclude the hydrogenation stage and abandon the use of alkali at the first stage of condensation of vanillin with acetone. This study is focused on the development of heterogeneous catalytic methods to produce valuable biologically active substances by the alkylation of vanillin with acetone or isopropanol. Results of a single-stage
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