Synthesis of Carbonated Fatty Methyl Esters Using Supercritical Carbon Dioxide

Abstract

The two-step syntheses of the cyclic carbonates carbonated methyl oleate (CMO) and carbonated methyl linoleate (CML) are reported. First, synthesis of epoxides through well-precedented chemical reactions of unsaturated fatty methyl esters with hydrogen peroxide and formic acid was accomplished. Next, a carbonation reaction with a simple tetrabutylammonium bromide catalyst was performed, allowing the direct incorporation of carbon dioxide into the oleochemical. These syntheses avoid the use of the environmentally unfriendly phosgene. The carbonated products are characterized by IR, 1H NMR, and 13C NMR spectroscopy and studied by thermogravimetric analysis (TGA). Also reported is the synthesis of a similar cyclic carbonate from the commercially available 2-ethylhexyl epoxy soyate. These carbonates show properties that may make them useful as petrochemical replacements or as biobased industrial product precursors.

Chemically Modifying Vegetable Oils to Prepare Green Lubricants

“…Fatty ester carbonates have the physical and chemical properties useful for preparing different valuable chemicals for many applications [132][133][134][135]. There are two main benefits of the conversion of fatty acid derivatives/epoxidized oils into cyclic carbonates.…”

“…Tamami et al reported on the synthesis of carbonated soybean oil from epoxidized soybean oil at an atmospheric CO 2 pressure using tetra-n-butylammonium bromide ([Bu 4 N]Br) as a catalyst [137]. An improved protocol for the synthesis of carbonated oleo compounds was described by Doll et al [133]. They have synthesized carbonated methyl oleate and carbonated methyl linoleate from epoxy derivatives of fatty esters using supercritical carbon dioxide directly with a catalytic amount of tetrabutylammonium bromide.…”

“…Conversion of the olefinic functional groups into cyclic carbonates and the use of different nucleophiles to open the rings: Cyclic carbonates are attractive green intermediates that are nontoxic, biodegradable, and can easily be prepared by coupling carbon dioxide with epoxy fatty esters ( Figure 6). Fatty ester carbonates have the physical and chemical properties useful for preparing different valuable chemicals for many applications [132][133][134][135]. There are two main benefits of the conversion of fatty acid derivatives/epoxidized oils into cyclic carbonates.…”

“…The first one is the preparation of novel materials from renewable resources, and the second is recycling and exploiting of carbon dioxide into the value chain. The coupling reaction of epoxides with CO2 is an intensively studied field of research, and various homogeneous and heterogeneous catalysts have been reported for this reaction [133][134][135]. Han et al [136] employed imidazolium-based ionic liquids with varied alkyl chain lengths bearing different anions as a heterogeneous catalyst for preparing cyclic carbonates.…”

Carbonation of Epoxy Methyl Soyate at Atmospheric Pressure

“…This scheme was applied to epoxidized soybean oil and shown to convert the oxirane to the carbonate with carbon dioxide at atmospheric pressures in the presence of tetrabutylammonium bromide 12,13) . Similarly, it was shown that epoxidized methyl oleate could be carbonated with supercritical carbon dioxide 14) . The availability of epoxidized vegetable oils and the corresponding epoxidized esters suggests a ready supply of renewable substrates for the production of long chain cyclic carbonates.…”