Organic levulinic acid

In the acid hydrolysis process (79—81), wood is treated with concentrated or dilute acid solution to produce a lignin-rich residue and a Hquor containing sugars, organic acids, furfural, and other chemicals. The process is adaptable to all species and all forms of wood waste. The Hquor can be concentrated to a molasses for animal feed (82), used as a substrate for fermentation to ethanol or yeast (82), or dehydrated to furfural and levulinic acid (83—86). Attempts have been made to obtain marketable products from the lignin residue (87) rather than using it as a fuel, but currently only carbohydrate-derived products appear practical. 

HMF is an important versatile sugar derivative and is a key intermediate between bio-based carbohydrate chemistry and petroleum based industrial organic chemistry (1, 2). The most coimnon feedstock for HMF is fructose and reactions are carried out in water-based solvent systems using acid catalysis (3,4). HMF is unstable in water at low pH and breaks down to form levulinic acid and formic acid, resulting in an expensive HMF recovery process. In strongly polar organic co-solvents, such as dimethylsulfoxide (DMSO), levuhnic acid formation is reduced and HMF yields are improved (5). 

Table 1 Catalysts used for the dehydration of polysaccharides Organic acids Oxalic acid, levulinic acid, maleic acid, p-toluenesulfonic acid Inorganic acids Phosphoric acid, sulfuric acid, hydrochloric acid, iodine, or hydroiodic acid generated in situ...

The major soluble components of acid hydrolysates are sugars, such as xylose, glucose, and cellobiose furfurals, such as furfuraldehyde and hydroxymethyl furfural and organic acids, such as levulinic acid, formic acid, and acetic acid (13). When natural sources of cellulose are acid-hydrolized, numerous products can result, largely because of the hemicellulose materials. These make it difficult to produce a relatively pure sugar product and limit the utility of the acid hydrolysis process. 

The liquid portion of biomass-derived process samples may also contain carbohydrate degradation products, such as 5-(hydroxymethyl)-2-furaldehyde (HMF), levulinic acid, and furfural, as well as other components of interest, such as organic acids and sugar alcohols. Portfolio methods are available for the quantitative measurement of these degradation products and byproducts of polymer hydrolysis. 

Preparation. Tollens discovered that levulinic acid can be obtained by the action of dilute mineral acids on carbohydrates starting materials include sucrose, starch, glucose, furfural," and 4-hydroxymethylfurfural." In the Organic Syntheses procedure a solution of 500 g. of sucrose in 1 1. of water is treated with 250 ml. of... 

The rehydration product of HMF, levulinic acid, is also regarded as a potential biomass derived organic compound [35, 39,40]. Levulinic acid could be utilized as feedstock for several large volume chemicals (Fig. 7), e.g., methyltetrahydrofuran and levulinate esters (fuel additives), delta-amino-levulinic acid (herbicide), and diphenohc acid (replacer for bisphenol A for polycarbonates). 

Timokhin BV, Baransky VA, Eliseeva GD (1999) Levulinic acid in organic synthesis. Russ Chem Rev 68 73-84... 

In a subsequent report, the Ru precatalyst was immobilized on three different inorganic/organic hybrid sihca supports (1) amine-functionalized (Ru-N/SiO ), (2) phosphine functionalized (Ru-P/SiOj), and (3) thiol functionalized (Ru-S/SiO ) [50]. For levulinic acid hydrogenation to GVL, the performance of the catalysts decreases in the order of Ru-P/SiO > Ru-S/SiO > Ru-N/SiO. When compared to a Ru/C catalyst, the Ru/C exhibits a much higher turnover frequency (10 times greater than Ru-P/SiOj) but has an extremely low yield ( 7% after 12h). This is attributed to the poor selectivity of Ru/C to decompose formic acid to and CO. Furthermore, the Ru-P/SiOj catalyst was used in eight consecutive experiments without noticeable loss of selectivity or yield of GVL [50],... 

Butadiene Polylactic acid Pentanes, pentene Succinic acid Phenolics Ethanol Butanol Organic acids Furfural Polyols Levulinic acid Sorbitol Xylitol Others... 

Potential of C5 Platform 11.8 Levulinic Acid Organic Keto ... 

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