Recent advances on oxidation of alcohols over various types of materials as effective catalysts: An overview

Abstract

Alcohols belong to a family of priceless chemicals that are employed as raw materials for the production of several key intermediates in crucial industrial processes. The production of value-added compounds relies on oxidation, a critical step in organic synthesis. Oxidation of alcohols is very vital for production of a range of ketones, aldehydes, and acids needed to obtain plastics, detergents, paints, cosmetics, food additives, and medication intermediates industrially. A notable instance is benzyl alcohol oxidation to commercially essential substrates such as benzaldehyde that is a very important reaction because benzaldehyde is commonly used in textiles, agricultural, cosmetics, and pharmaceutical industries. It is noteworthy that the catalytic oxidation of alcohols can be regarded as an environmentally benign process because it avoids using toxic oxidants or high temperatures and instead it uses inexpensive sustainable oxidants like molecular oxygen. This work seeks to provide a review on recent investigations performed on oxidation of alcohols catalyzed by several types of catalyst materials such as inorganic metal complexes, metal organic frameworks (MOFs), zeolites, perovskites, spinels, metal oxides, metals, carbonaceous compounds, g-C₃N₄ composites, salts, and organic materials. Furthermore, characterization as well as catalytic tests are summarized to allow comparisons of catalysts performances, including reaction rate, product selectivity, conversion, and other factors. In fact, this study presents characteristics that affect selectivity, conversion, activity, reusability, and stability of catalysts. Besides, the critical underlying mechanisms behind the oxidation of alcohols are investigated in order to realize which oxidizing species are formed in practical applications of the processes. For performance optimization, effects of factors and reaction circumstances including temperature, solvents, catalyst dose, and oxidant are studied. Therefore, this review provides an overview of the underlying knowledge about employed catalysts indicating oxidation processes of alcohols can be carried out in various solvents employing diverse catalysts.