Biobased methacrylic acid via selective catalytic decarboxylation of itaconic acid

Authors: LANSING, JAMES - Orise Fellow; Murray, Rex; Moser, Bryan

Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2017
Publication Date: 2/23/2017
Publication URL: http://handle.nal.usda.gov/10113/5661532
Citation: Lansing, J.C., Murray, R.E., Moser, B.R. 2017. Biobased methacrylic acid via selective catalytic decarboxylation of itaconic acid. ACS Sustainable Chemistry & Engineering. 5(4):3132-3140.

Interpretive Summary: This research describes a renewable and sustainable route to methacrylic acid, an important commodity monomer used for the production of numerous commercially significant polymers with an annual worldwide market value in excess of nine billion dollars. The traditional route to methacrylic acid is petrochemically-based and involves reaction of acetone with concentrated sulfuric acid and hydrogen cyanide. Bio-based methacrylic acid is of interest to obviate the safety, toxicity, and environmental deficiencies of the conventional petrochemical method. Currently, no viable bio-based approaches to methacrylic acid have been described or implemented commercially. The objective of this study was to develop a commercially viable process from environmentally benign materials with high selectivity, conversion, and yield. The results indicated that itaconic acid, a bio-based material obtained from fermentation of simple sugars, can be selectively decarboxylated in the presence of certain catalysts to yield methacrylic acid in aqueous solvent. These results will be important to commercial producers of methacrylic acid and its resulting polymers, along with downstream users of such products who are interested in sustainability and renewable materials. This research may ultimately provide a renewable alternative to an otherwise nonrenewable commercial material, thus further reducing the environmental impact of and demand for petroleum and its various products.

Technical Abstract: We report a bio-based route to methacrylic acid via selective decarboxylation of itaconic acid utilizing catalytic ruthenium carbonyl propionate in an aqueous solvent system. High selectivity (>90%) was achieved at low catalyst loading (0.1 mol %) with high substrate concentration (5.5 M) at low temperature (210–225 deg. C) and pressure (less than or equal to 425 psig) relative to previous contributions in this area. Direct decarboxylation of itaconic acid was achieved as opposed to the conjugate base reported previously, thereby avoiding basification and acidification steps. Also investigated was catalytic manganese (II) oxalate (5 mol %), but low yield (4.8%) and evolution of carbon monoxide via oxalate decomposition was problematic. Attempts at stabilization of the catalyst with triphenylphosphine were unsuccessful, but it exhibited greater catalytic efficacy (14.0% yield) than the manganese catalyst (4.8% yield) at 5 mol %. Neither carbon monoxide nor propylene (excessive decarboxylation) were detected during ruthenium-catalyzed decarboxylation. In addition, cosolvents such as tetraglyme lowered vapor pressures within the reaction vessel by >100 psig while minimizing decomposition of starting acids. In combination, these findings represent improvements over existing methodologies that may facilitate sustainable production of methacrylic acid, an important petrochemically-based monomer for the plastics industry.