p‐Cymene as Solvent for Olefin Metathesis: Matching Efficiency and Sustainability

Abstract

The underexploited biorenewable p-cymene is employed as a solvent for the metathesis of various substrates. p-Cymene is a nontoxic compound that can be obtained in large amounts as a side product of the cellulose and citrus industry. For the cross-metathesis of estragole with methyl acrylate, this solvent prevents the consecutive double-bond isomerization of the product and affords the best yield of all solvents tested. Undesired consecutive isomerization is a major challenge for many substrates in olefin metathesis, including pharmaceutical precursors, and the use of p-cymene as a solvent may be a way to prevent it. This solvent results in a better metathesis performance than toluene for the three substrates tested in this work, matching its performance for two other substrates.

Ruthenium‐Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

“…The reactions were carried out under a flow of nitrogen in a Schlenk tube and stopped after 16 h at which time full conversion of the starting alcohol had not been achieved. The reaction with Ru 3 (CO) 12 gave 10 % yield of naphthalene in refluxing xylene (entry 1) while the yield increased to 26 % in refluxing p ‐cymene (entry 2). A further improvement to 39 % was obtained in the presence of PPh 3 (entry 3) and a significant amount of 2‐naphthaldehyde could also be observed in all three cases.…”

Functional nano-catalyzed pyrolyzates from branch of Cinnamomum camphora

“…9-Octadecenoic acid, (E) - (0.31%) for medical research. P-Cymene (0.26%) is a kind of expectorant, antitussive and antitussive drug, and is also an intermediate in the manufacture of other pharmaceutical products (Granato et al, 2017).…”

Transformations of bio‐sourced 4‐hydroxyphenylpropanoids based on olefin metathesis

“…[37,40] The cross metathesis of estragole (2) with a fourfold excess of methyl acrylate was optimized in 1,2-dichloroethane ([2] = 0.125 M) in the presence of 0.5 mol% of Ru4 at 70°C for 4 h to give the expected product in 79 % yield with a limited amount of double bond migration of about 10 %. [41] It was observed that the self-metathesis of (2) was more important in concentrated solution reaching 14-16 % ([2] = 0.25 M or without solvent) and that the migration towards a styryl derivative was favoured by a higher catalyst loading. The nature of the solvent was crucial for the selectivity of the cross metathesis reaction and considering productivity and selectivity aspects, p-cymene was found to be an excellent solvent leading to 95 % conversion of (2) into the cross metathesis product in % yield.…”