Spongy titanosilicate promotes the catalytic performance and reusability of WO₃ in oxidative cleavage of methyl oleate

Abstract

Proposed “dissolve and precipitate” reaction mechanism of WO3–STS catalyzed MO oxidative cleavage reaction.

Solvent‐Free Aerobic Oxidative Cleavage of Methyl Oleate to Biobased Aldehydes over Mechanochemically Synthesized Supported AgAu Nanoparticles

“…The catalyst Ag 8 Au 92 /SiO 2 , besides affording higher productivities, was the only one to produce 2-decenal (9) starting from 1 h, but also found at longer reaction times (4 h and 16 h) and with ZrO 2 . As a function of temperature, the samples that showed productivity toward aldehydes (at 60 and 80 °C) had similar ratios of nonanal (5), 2-undecenal (14), and heptanal (13). The reaction at 60 °C was the only one that produced 9-octadecenal (15), derived directly from the original hydrocarbon chain composed of 18 carbons.…”

“…The oxidative cleavage of methyl oleate ( 1 ) may proceed through a variety of possible pathways, as demonstrated in Scheme 1. The main reason for this is that step i), previously described by the formation of the epoxide, is able to either generate the direct products of cleavage (Box A) or dehydrate forming two conjugated double bonds vicinal to the original unsaturation, that lead to the other sets of main products indicated in Box B and Box C. In addition, other byproducts derived from partial decomposition, hydrolysis and oxidation mechanisms may be formed, such as carboxylic acids and alcohols [13] …”

“…The main reason for this is that step i), previously described by the formation of the epoxide, is able to either generate the direct products of cleavage (Box A) or dehydrate forming two conjugated double bonds vicinal to the original unsaturation, that lead to the other sets of main products indicated in Box B and Box C. In addition, other byproducts derived from partial decomposition, hydrolysis and oxidation mechanisms may be formed, such as carboxylic acids and alcohols. [13] In this study, we synthesize the catalysts using a bottom-up mechanochemically induced approach, inspired by what has been previously reported. [17] In contrast to solution-based methodologies, this synthesis does not need any solvents or surfactants, suiting green chemistry principles, such as atom economy and waste prevention.…”

“…The mechanism of olefin oxidation proceeds in three steps: i) formation of epoxides on olefinic double bonds; ii) epoxide opening to vicinal diols as intermediate; iii) aerobic cleavage of the C−C bond between the vicinal diols, affording two carbonyl compounds. The reaction has also been reported to occur without the formation of vicinal diols [13] …”

“…The reaction has also been reported to occur without the formation of vicinal diols. [13] In recent years, gold-based catalysts have received increased attention in the field of selective oxidation catalysis for their performance in reactions such as the epoxidation of alkenes, and the oxidation of alcohols or carbon monoxide. [14] The formation of metallic Au nanoparticles has proven to be approachable by green strategies with lower costs associated, increasing the catalysts surface area, robustness, recyclability, and stability in comparison to their bulk counterparts.…”