RUDN University and Shahid Beheshti University (SBU) chemist together with colleagues from Iran proposed a catalyst for the simple and inexpensive oxidation of alcohols to aldehydes, which are widely used, for example, to create medicines and plastics. Unlike its analogues, the catalyst does not require harsh reaction conditions and dangerous chemicals, and the oxidizer is ordinary air. The results are published in the Journal of the Taiwan Institute of Chemical Engineers.
Aldehydes are organic substances in which a carbon atom combines with oxygen and hydrogen. This broad class of compounds is used in almost all areas of chemistry. For example, formaldehyde is used to make resins and medicines, while acetaldehyde is used to make acetic acid and plastics. One of the ways to produce aldehydes is the oxidation of alcohols. For this purpose, inorganic oxidizing agents are usually used, but they are toxic and unsafe for the environment.
"Using oxygen as an oxidant is very common; however, reactions that require pure O2 as an oxidant do not fulfill the standard criteria for an appropriate reaction because of the cost of acquiring, supply, maintaining, and utilizing the pure O2 cylinder is expensive. Thus, there is a definite need for catalysts that use air as an inexpensive and non-toxic oxidant that produces water as the only by-product, " said Ahmad Shaabani, a leading researcher at the Joint Institute for Chemical Research of RUDN and SBU
RUDN University chemist together with colleagues from Iran created a catalyst for the oxidation of alcohols in green conditions. The oxidizer is air oxygen, the reaction itself does not require harsh conditions and dangerous chemicals and gives a high yield of aldehyde. In this case, the catalyst itself can be used several times.
The new catalyst is based on metallophthalocyanines with a metal centre and organic ligands. In the centre of these complexes is a cobalt atom with organic cyclic fragments diverged from it. These complexes attach to another complex molecule (the scaffold) via an amino group. Chemists tested different initial alcohols. In 4-9 hours, 82-98% of the reagent was successfully oxidized and 80-95% of the final aldehyde was obtained. After four cycles of use, the efficiency of the catalyst dropped, but remained high -; 63%.
"The integration strategy of various types of catalytically active metal phthalocyanine in the MOF substrate generates a low-cost, simple, and efficient method for synthesizing heterogeneous catalysts. It is noteworthy that air as an oxidizing reagent in the absence of additional oxidants during the reaction, apt reaction time, high performance, and recyclability of the catalyst without losing its activity are other benefits of the introduced catalyst," said Ahmad Shaabani, a leading researcher at the Joint Institute for Chemical Research of RUDN and SBU.