Formation of levulinic acid from

The mechanism of formation of levulinic acid from carbohydrates bears discussion. The subject was first taken up by Pummerer and co-workers in 1935 [166], who first recognized that HMF 1 was an intermediate which underwent rehydration to open chained products, but otherwise gave an oversimplified interpretation that involved the "dismutation" of oxygen from the CH2OH group in 66 to the terminal aldehyde (Scheme 21). 

Pioetz T (1941) The formation of levulinic acid from carbohydrates. Naturwissenschaften 29 707-708... 

The mechanism of the formation of levulinic acid probably involves the substance 5-hydroxymethylfurfural (XXVIII), which may also be obtained from sucrose by treatment with dilute oxalic acid. This... 

The analogous product from the pentose glycals and 2-deoxy-pentoses would be furfuryl alcohol, but, as it is unstable and is readily converted into levulinic acid under the conditions of formation, it is difficult to isolate. The spectral data52 and the fact that levulinic acid is the common product from 2-deoxy-D-erythro-pentose, D-ara-binal, and furfuryl alcohol19 substantiate the supposition that the mechanism is analogous to that just described. Other (unknown) products are formed in significant yield from the dehydration of 2-deoxy-D-ert/fhro-pentose.52,84 The mechanism of formation of levulinic acid is discussed in Section V (see p. 212). 

Levulinic Acid. Dehydration of glucose or other monomeric and polymeric C6 sugars leads to the direct formation of levulinic acid (LA) as a potential primary building block for the biorefinery, and several reviews have described its potential commercial utility 477,478 The preparation of levulinic acid is not difficult, although the mechanism of its formation from carbohydrates is complex, and offers several alternative decomposition pathways (equation 3).479... 

Production of levulinic acid from cellulose produces one mole of formic acid for every mole of levulinic acid produced on a stoichiometric basis. Large volume production of levulinic acid would yield large quantities of formic acid. We have found that AL and formic acid will react with olefins and water in the presence of acid catalysts to yield both formate and levulinate esters. All these products are attractive fuel additives. 

Formation of 7-pentalactone from levulinic acid has been proposed by Tressl et al. (1978d). 

Scheme 9.3.2 Formation of HMF levulinic acid from hexoses.

Pummerer R, Guyot O, Birkofer L (1935) Mechanism of levulinic acid formation from hexoses. II. A hydroxyl-free glucosan-like substance. Berichte 68B 480-493... 

In his cephalosporin synthesis methyl levulinate was condensed with cysteine in acidic medium to give a bicyclic thiazolidine. One may rationalize the regioselective formation of this bicycle with the assumption that in the acidic reaction mixture the tMoI group is the only nucleophile present, which can add to the ketone. Intramolecular amide formation from the methyl ester and acid-catalyzed dehydration would then lead to the thiazolidine and y-lactam rings. The stereochemistry at the carboxylic acid a-... 

The carboxyl terminated ACPA, 4,4 -azobis-(4-cya-nopentanoic acid), turned out to be a suitable reagent in condensation reactions. This compound can be prepared by Strecker s synthesis from levulinic acid following the method of Haines and Waters [12]. Regarding the formation of polymeric azo initiators, Matsakuwa et al. [13] reported on the condensation of ACPA with various diols and diamines in the presence of a condensation agent, I-methyl-2-chlorpyridinium iodide, and a cata-... 

Levulinic acid and formic acid are end products of the acidic and thermal decomposition of lignocellulosic material, their multistep formation from the hexoses contained therein proceeding through hydroxymethylfurfural (HMF) as the key intermediate, while the hemicellulosic part, mostly xylans, produces furfural.A commercially viable fractionation technology for the specific... 

Scheme 5). However, this reaction is not as easy as it looks since numerous side reactions may occur. Antal et al. showed that four different classes of reactions can take place from hexoses (1) their dehydration leading to the formation of HMF, (2) their fragmentation, (3) their isomerization, and (4) their condensation leading to the formation of insoluble polymers and humins [58, 69]. Later, Van Dam and Cottier showed that at least 37 products can be produced, thus showing the complexity of this reaction. In particular, they highlighted that HMF can react with water, leading to the formation of undesirable side products such as levulinic and formic acids [68, 70]. 

There are few good synthetic methods for these compounds because they are unstable, and must be preserved at low temperatures (Section 3.14.3.6). 2-Hydroxythiophene was first prepared by oxidation of the Grignard reagent, and later from 2-thienyllithium. The compound was also obtained by acid-catalyzed dealkylation of 2-r-butoxythiophene (equation 60). 3-Hydroxythiophene was also obtained by oxidation of 3-thienyllithium (63AHC(1)1>. 5-Methyl-2-hydroxythiophene was obtained in low yield by the Paal synthesis from levulinic acid (equation 61 Section 3.15.3.1.3). 3,5-Dinitro-2-chlorothiophene was converted to 3,5-dinitro-2-hydroxythiophene by hydrolysis with sodium formate in anhydrous methanol (equation 62). 

Similarly, with the same type of photocatalyst (Pt/TiC>2 or Fe2C>3) the decomposition of levulinic (4-oxopentanoic) acid in oxygen-free aqueous solution has been investigated in detail (60). In addition to the decarboxylation reaction, oxidative C-C scissions led to propionic and acetic acids (further converted into methane and ethane) and reductive cleavages to acetone and ethanal. The formation of acetone was apparently favoured by higher Pt contents (however product distributions referred to equal illumination durations and not to equal conversions). It was suggested that the variety of products resulted from the presence of two functional groups in levulinic acid. The quantum yield was probably of the order of 5 x IQ-3. 

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