Sulfated metal oxides: eco-friendly green catalysts for esterification of nonanoic acid with methanol

Abstract

Considering the need of applicability of green chemistry in research, a series of heterogeneous catalysts, viz., sulfated iron oxide, zirconia supported tungstophosphoric acid and sulfated zirconia have been synthesized by a solvent-free method. The prepared catalysts were used in the esterification of nonanoic acid with methanol and were compared with ion exchange resins for the assessment of their catalytic performance. Sulfated iron oxide was found to be best with an acid conversion of 83%, which is quite comparable with Amberlyst 15 and Dowex50Wx2. The high catalyst loading, cost, low thermal stability, and long reaction time make ion exchange resins uneconomical to use over other alternatives that result in same efficiency with low cost. Sulfated iron oxide was further optimized for its preparation conditions for high catalytic performance in the esterification reaction. The catalysts were characterized for their crystallinity, surface morphology, composition, weight loss, and structure by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The evaluated catalysts were compared on the basis of their preparation time, catalytic performance, catalyst loading, reaction time, and overall cost.

Photochemical Synthesis of Lactic Acid Esters at Ambient Temperature Employing Sulfonically Fuctionalized N/W‐Doped Nano‐semiconductor

“…As observed and inferred (Fig. 6(d)) conversion increased appreciably till 0.06 g mL −1 , afterward showing a flat region, this fact recommends the accessibility of an adequate number of acid sites capable of fetching the reaction to equilibrium (32,(39)(40)(41)(42)(43)(44)(45)(46)(47). This increase in the conversion is directly related to the increase in the quantity of active acid sites available for the reaction to proceed.…”

“…So according to Le-Chatelier's principle, an excess of any one of the reactants in the reaction can shift the equilibrium toward forward direction. This increases the forward rate constant of the reaction, favoring the conversion and hence yield of the product ester (32,(39)(40)(41)(42)(43)(44)(45)(46)(47). Alcohols can be easily separated by distillation from the reaction mixture, and they are comparatively cheaper than acids.…”

Elementary Transformation of Glycerol to Trivalerin: Design of an Experimental Approach

“…Valeric acid (>99%) and glycerol (>99%) AR were supplied by Loba Chemie, Ltd. Iron­(III) oxide and ammonium sulfate were purchased from Merck (Mumbai, India). Sulfated iron oxide was prepared via a procedure we described previously. ,, …”

“…Their high acidity, low cost, large surface area, and use of low catalyst loading to achieve the desired results in the organic reactions have proven them to be efficient. Many researchers have investigated various sulfated metal oxides, i.e., sulfated tin oxide, sulfated zinc oxide, sulfated iron oxide, sulfated copper oxide, their mixed oxides, etc., in different organic reactions. ,,− …”

Bioinspired Enzymatic Synthesis of Terpenoid-Based (Meth)acrylic Monomers: A Solvent-, Metal-, Amino-, and Halogen-Free Approach

“…A serious drawback of the synthetic methods used to prepare the monomers mentioned above is that they are not environmentally friendly. They use solvents, alkyl chloride reagents, metal or amino-based catalysts, and/or harsh conditions (acidic medium and high temperatures). , In addition, under these conditions, it is difficult to avoid the polymerization of unsaturated bonds, which are largely present on the molecular structure of terpenes. Therefore, there is an urgent need of greener and more efficient methods.…”