Synthesis and characterization of acidic nano diatomite and its application in aldol reaction of kojic acid

Melanogenesis is a process in which melanocytes produce melanin that is initiated by the tyrosinase enzyme after exposure to UV. Although the primary role of tyrosinase is the production of melanin, these pigments protect the skin from UV rays .But overproduction and alteration in the production of melanin causes darkening of the skin and can cause melasma [1] . Natural tyrosinase inhibitors based on kojic acid tyrosinase inhibitor compounds are of great attentions in industry due to its ease of synthesis and economic approaches [2,3].In the synthesis process of organic compounds, the aldol reaction is one of the most important reactions used to form carbon-carbon bonds. The importance of forming this bond in the synthesis of organic compounds is that large molecules can be made from small molecules. Usually, the aldol reaction is carried out in the presence of an acid or base. As a part of our continued research interest in the area of heterogeneous catalysis [4,5], we investigated the applicability of the acidic nano diatomite modified base as recyclable heterogeneous catalyst for aldol reaction of the kojic acid. In this project, acidic nano diatomite catalysts was prepared and synthesized after performing three steps of surface catalyst functionalization. Then the prepared acidic nano-diatomite catalyst characterized and investigated by TG, SEM/EDS, FTIR, XRD and BET measurements. Various conditions such as temperature, solvent, and catalyst content in the final product synthesis process was investigated and the optimum conditions were determined. Overall efficiency of synthesis process in aldol reaction with a 1:1 molar ratio of benzaldehyde and kojic acid in the optimum conditions and in the presence of acidic nano-diatomite achieved to 89%. Also product identification was analyzed and validated by FTIR and NMR spectra. Products with very good yields and less time were obtained as compared to previous similar researches.

کلیدواژه ها:

melanin ، tyrosinase inhibitors ، aldol reaction ، kojic acid ، acidic nano diatomite catalyst