Acid‐catalyzed Oxidation of Levulinate Derivatives to Succinates under Mild Conditions

Abstract

Levulinate derivatives are an attractive platform for the production of renewable chemicals. Here we report on the oxidation of methyl levulinate into dimethyl succinate with peroxides under mild conditions using Brønsted and Lewis acid catalysts. Selectivities to succinate and acetate derivatives of approximately 60 and 40 %, respectively, were obtained with strong Brønsted acids in methanol. Although the molecular structure (i.e., carbon-chain length and branching around the C=O group) and the oxidant type affect the product distribution, solvent choice has the strongest impact on changing the location of oxygen insertion into the carbon backbone. Specifically, switching the solvent from methanol to heptane resulted in a decrease in the succinate/acetate ratio from 1.6 to 0.3. In contrast to Brønsted acids, we demonstrate that the nature of the metal cation is responsible for changing the reaction selectivity of water-tolerant Lewis acidic triflate salts.The conversion of renewable resources into commodity and specialty chemicals through chemical or biological routes has attracted considerable attention. [1] Thermocatalytic routes offer an attractive alternative to biological routes, with less stringent requirements for temperature and pH control, as well as potentially less energy-intensive product separation and purification processes. [1a, 2] Succinic acid (SA) has been identified as one of the top 12 building blocks from biomass by the US Department of Energy. [3] The market for SA is expected to exceed $ 1.1 billion in revenue by 2020. [4] Succinates, formed from the esterification of SA with monoalcohols, are important plasticizers, lubricants, and chemical intermediates. [5] A thermocatalytic route to produce SA and other succinate derivatives from renewable resources is highly desirable.Levulinic acid (LA) is a key platform molecule that can be readily produced from lignocellulosic carbohydrates. [6] Upon scale up, the estimated LA price is expected to decrease to less than $ 1 kg À1 from the current commercial price of approximately $ 3.5 kg À1 . [7] The carbonyl group in LA and its esters can be oxidized to produce SA and its esters, respectively; however, linear aliphatic ketones are generally difficult to oxidize selectively. Consequently, only a few studies, mostly using vanadium-, ruthenium-, and manganese-based catalysts, have been reported on the oxidation of LA derivatives. [8] These catalytic systems suffer from several challenges, including necessitating high reaction temperatures, using toxic reagents, or releasing a stoichiometric amount of CO 2 . Recently, Podolean et al. demonstrated that Ru-based magnetic nanoparticles are efficient catalysts for the oxidation of LA into SA under 10 bar of O 2 at 150 8C. [1b] The authors hypothesized that strong Brønsted acid sites are responsible for catalyzing the oxidation of the LA carbon backbone via a Baeyer-Villiger (BV) mechanism. Unfortunately, no systematic studies on the role of Brønsted acids in the BV oxidation of LA into SA were report...

Catalytic Synthesis of Levulinate Esters over Zirconia and its Modified Forms Coated on Honeycomb Monoliths: Green Synthesis

“…From energy to manufacturing, levulinic acid can be used in the preparation of resins, pharmaceutical agents and biofuels [11,12]. Levulinate ester or alkyl levulinate is synthesized from esterification reaction of levulinic acid with various alkyl alcohols [13] (Scheme-I).…”

Synthesis of Itaconic Acid Ester Analogues via Self-Aldol Condensation of Ethyl Pyruvate Catalyzed by Hafnium BEA Zeolites

“…Nonetheless, compound 13 is likely produced from the lactonization of a C7 molecule (reaction f in Scheme S1), indicating that although lactonization is feasible, the confining effects of the zeolite pores may limit this pathway for larger molecules. 34 Metal oxides with Brønsted basicity typically employed for aldol reactions, including MgO and hydrotalcite, 35 show EP conversions of less than 13% and selectivities of less than 18% (Table S1, entries [8][9][10][11][12]. In these systems, pyruvic acid produced by the hydrolysis of EP is expected to deactivate the basic sites.…”

Esterification of Levulinic Acid to Levulinate Esters in the Presence of Sulfated Silica Catalyst

“…Conversion of carbohydrate derived biomass for basic chemical production has received a great attention as biomass is regarded as alternative source for the depleting fossil fuels (Cirujano et al 2015a;Wang et al 2015). Levulinic acid (LA) is a versatile platform chemical and considered as one of the top twelve building block chemicals derived from biomass (Ahlkvist et al 2016;Ramli & Amin 2017).…”

“…Levulinic acid (LA) is a versatile platform chemical and considered as one of the top twelve building block chemicals derived from biomass (Ahlkvist et al 2016;Ramli & Amin 2017). LA can be used in several applications including fuel additives, pharmaceutical agents, resin precursors, fragrance and flavouring agents (Cirujano et al 2015a;Wang et al 2015). Esters of LA (levulinate esters) are the important compounds among the LA derivatives which are employed in fragrance and flavouring industry and can be applied as fuel additives (Démolis et al 2014;Song et al 2015).…”