Levulinate esters prepared

Levulinic esters. Levulinic esters of sugars can also be prepared by Mukaiyama s method for esterification with 2-chloro-l-methylpyridinium iodide (8, 95-96). Deblocking of the ester group is possible with hydrazine hydrate (1 equivalent, 20°).1... 

Levulinic esters. Alcohols can be protected as the levuhnates, readily prepared by reaction of the alcohol with the anhydride in pyridine at 25°. The protecting group can be removed by NaBH4, which selectively reduces carbonyl groups in the presence of ester groups. This reaction is usually quantitative. This... 

Besides HMF, the rehydration product levulinic acid is also regarded as a potential biomass-derived organic compound. Large volume chemicals can be prepared from levulinic acid by chemical conversion, among them methylte-trahydrofuran and levulinate esters (fuel additives), delta-amino-levulinic acid... 

Alkyl levulinate esters 72 can be prepared by homogeneous acid-catalyzed Fischer esterification of LA [188], under solid acid catalysis [189, 190], by acid-catalyzed... 

Levulinic acid is obtained by hydrolysis of cellulose-containing biomass. R D is actively conducted at DuPont Co. to employ levulinic acid for the synthesis of pyr-rolidones (solvents and surfactants), a-methylene-y-valerolactone [monomer for the preparation of polymers similar to poly(methyl methacrylate)], and levulinic acid esters (fuel additives) [26]. 

Addition of the anion of 2-methyl-l,3-cyclopentadione (348) to protoane-monin (349), easily prepared from levulinic acid in four steps (207), led to adduct 350 in low yield due to ready self-condensation (Scheme 39). Transesterification with acidic methanol set the alcohol free, which cyclized spontaneously to the 1 1 mixture of ketals 351 and 352. To enhance the yield of the ketal 352, ketal 351 was recycled by equilibration in acidic methanol. Under Kharash-Grignard conditions, the isopropenyl group added unselectively in 1,4-mode and the ester enolate 353... 

The levulinoyl esters are prepared from the free hydroxyl group by treatment of levulinic acid with DCC [255,256] or l-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (EDAC) [257] in the presence of DMAP (O Scheme 38). Additionally, 3 - and 5 -0-levulinyl protected derivatives of 2 -deoxy nucleosides have been prepared by regioselective enzymatic acylation using a variety of lipases and acetonoxime levulinate as acylating agent [258]. In contrast to other ester substituents, the 0-levulinoyl group is far less prone to migration [259]. 

After Adams and Long (71) had established the structure of monocrotic acid unequivocally by the synthesis of a,/3-dimethyllevulinic acid (LXIV), these workers established some grounds for the elimination of the unsatisfactory structures among those three postulated for monocrotalic acid. One of the intermediates prepared in the synthesis of a,/3-dimethyl-levulinic acid was the substituted malonic ester LXXV. By acid hydrolysis, the malonic acid derivative (LXXVI), which would be formed first, might then isomerize spontaneously to LXIX, one of the possibilities for mono-... 

As previously discussed, 2 -i- 2 photocycloaddition can be stereoselective when carried out with rigid starting materials. When unsaturated lactam 178, prepared in a few steps from levulinic acid and (S)-( -f )-valinol, was subjected to photocycloaddition with ethylene, a very diastereoselective addition (de = 85%) takes place [152] (Scheme 29). Acidic methanolysis produces the corresponding esters and recovered valinol. Preferential formation of 179 involves an attack of ethylene from the convex side of the molecule. 

Fagan PJ, Korovessi E, Manzer LE, Mehta R, Thomas SM (2003) Preparation of levulinic acid esters and formic acid esters from biomass and olefins. WO 2,003,085,071 A1... 

Manzer LE (2005) Preparation of levulinic acid esters from alpha-angelica lacfame and... 

An attempt to convert methyl levulinate to vinyl levulinate was unsuccessful (Figure 2). Heating methyl ester with vinyl acetate in acidic mercuric acetate gave a-angelica lactone as the major product rather than the vinyl ester. Vinyl levulinate was previously prepared by the mercuric ion-catalyzed reaction of levulinic acid with vinyl acetate (id), so this older preparation will be used for future studies. a-Angelica lactone can also be prepared by dehydration of the acid without the use of vinyl acetate (/ 7). 

The reaction of ethyl levulinate with furfural gave a condensation product, of which the major isomer is presumed to be the 8-furfurylidenelevulinate ester, since the acid-catalyzed reaction of furfural with levulinic acid produces this isomer 19). Some of this reaction could occur during the preparation of ethyl levulinate, since furfural and acid catalyst are present, but no furfurylidenelevulinate ester was detected in the ether extract. Thus, if condensation reactions occur, the products stay in the char or the resin products and are likely of higher molecular weight. 

A similar reaction of ethyl levulinate was conducted with a UF preparation. The acid-catalyzed reaction incorporated the levulinate into the resin structure, forming aii insoluble mass. This reaction does not occur to a large extent during the initial particle board degradation owing to the large volume of ethanol solvent however, it can cause a problem in the workup of the products after the ethanol has been removed. The reaction explains the failure of attempts to distill ethyl levulinate directly from the levulinate-resin product mixture without prior extraction of the ester from the resin. These attempts resulted in low ester yields and the formation of intractable resin. Thus, by extracting the ester we can avoid the inadvertent condensation reaction with the resin. 

As shown in eq. (12.30), levulinic acid ethylester has two kinds of carbonyl ketacarbonyl and estercarbonyl. Me2TiCl2 then selectively reacts with a keto-carbonyl group, and the methylated alcohol esters are prepared in 90% or more yield [83]. 

Levulinic acid esters have been studied extensively (11) as fuel additives. Ethyllevulinate meets or exceeds the ASTM D-975 diesel fuel standard and numerous other qualifiers. It can be prepared directly from levulinic acid and... 

Figure 10. Preparation of Levulinic Acid Esters from Olefins, Water and...

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