Furfural-5-carboxylic acid

Furfural [98-01-1] M 96.1, b 54-56°/llmm, 59-60°/15mm, 67.8°/20mm, 90°/65mm, 161°/760mm, dj° 1.159, n2D 1.52608. Unstable to air, light and acids. Impurities include formic acid, B-formylacrylic acid and furan-2-carboxylic acid. Distd over an oil bath from 7% (w/w) Na2CC>3 (added to neutralise acids, especially pyromucic acid). Redistd from 2% (w/w) Na2C(>3, and then, finally fractionally distd under vacuum. It is stored in the dark. [Evans and Aylesworth IECAE 18 24 1926). 

The metabolism of several furan derivatives, e.g. furan-2-carboxylic acid and furan-2-carbaldehyde (furfural), was studied in 1887 by Jaffe et al. (1887CB2311), and most of this early work has been summarized (B-47MI10900). The metabolism of furfural (127 Scheme 12) is of special interest since it yields furfuracryluric acid (furylacryloylglycine) (128) as... 

At that time, however, these reactions were not brought to the level of preparative synthesis of nitriles. The main obstacle seemed to be further transformation of the nitriles to acids. In some cases, upon treating al-doximes with alkalies, it was not at all possible to fix nitriles since they immediately converted to acids. The anti(E)-isomers exhibit an enhanced reactivity in these cases. Thus, when boiled in 2 N NaOH, -aldoximes are slowly converted to a mixture of the corresponding carboxylic acids and sy/i(Z)-aldoximes to evolve ammonia (36JA1227). Under these conditions for 4 hr the - and Z-benzaldoximes undergo 13 and 48% conversion to form benzoic acid in 10 and 38% yield, respectively. Analogously, the -and Z-oximes of furfural, under the same conditions for 1.5 hr, are converted to furan-2-carboxylic acid in 33 and 62% conversion and 18 and 49% yield, respectively. 

Furoic acid (furan-2-carboxylic acid, or pyromucic acid) is used as a bactericide, and the furoate esters are used as flavoring agents, as antibiotic and corticosteroid intermediates. It is obtained by the enzymatic or chemical/catalytic aerobial oxidation of furfural (2-furalaldehyde) the latter is the only unsaturated large-volume organic chemical prepared from carbohydrates today. D-Xylose and L-ara-binose, the pentoses contained in the xylan-rich portion of hemicelluloses from agricultural and forestry wastes, under the conditions used for hydrolysis undergo dehydration to furfural. 

Furan carboxylic acids usually decarboxylate readily, and this method is often used in the laboratory for the preparation of furans. Furan itself can be obtained in good yield from 2-furoic acid in quinoline, with a copper catalyst, while industrial methods employ the catalytic decarbonylation of furfural. Copper powder, copper oxide or copper bronze, or heavy metal oxides,22 are the best catalysts, in combination with quinoline as solvent and weak base.23-28 Dann et al,2fl decarboxylated 2,5-dimethyl-3-furoic acid in 50% yield using barium hydroxide. 3-Furoic acid, which is difficult to obtain in large quantities, is best prepared by controlled decarboxylation of the easily prepared furan tetracarboxylic acid. 

Methyl formate, ethyl formate, carboxylic acids and derivatives, acetic acid CH3COOCH, acetic anhydride CH3COOCOCH3, formic acid HCOOH, oxalic acid HOOCCOOH, phthalic anhydride C3H4O3 Acetaldehyde CH3CHO, acrolein H2C=CHCHO, formaldehyde HCHO, furfural C5H4O2... 

Poly(iso-butyl vinyl ether)-furfural condensate obtained through the condensation of furfural with poly(iso-butyl vinyl ether) in benzene medium in presence of hydrochloric acid at 50 °C on treatment with sulfuric acid yields a carboxylic acid cation-exchange resin with a capacity of 5.8 meq/g. 

The reactivity of achiral Ru compounds for the hydrogenation of functionalized ketones has not been extensively studied. RuCl2 P(C6H5)3 3 reduces y-keto carboxylic acid at 180 °C to the corresponding y-lactone (Eq. 2.15) [115]. Heterogeneous Ru/C catalyzes the atmospheric pressure hydrogenation of furfural in water at 25 °C [86]. Under such mild conditions, glucose is industrially converted to sorbitol (Eq. 2.16) [116]. At elevated temperature and pressure, tetramethyl-l,3-cyclobutanedione can be converted to a 98 2 diastereomer mixture of the diol (Eq. 2.17) [117]. 

The waste water of all furfural plants contains some carboxylic acids, with acetic acid being the principal load, ranging from 1 to 5 percent by weight, as well as some furfural, in concentrations up to 600 ppm. The furfural concentration depends on the quality of the first distillation column, with good columns going down to 50 ppm. 

All furfural processes lead not only to furfural but also to carboxylic acids. Depending on the raw material employed, the production of carboxylic acids may exceed the production of furfural. 

In the normal recovery schemes treated so far, the acid waste water of the furfural process was directly submitted to a separation so as to obtain the carboxylic acids as a byproduct, for sale. It is, however, instructive to realize that apart from the small percentage of... 

The intrinsically high reactivity of the furan nucleus is further exempUlied by the reaction of furfural with excess halogen to produce mucohalic acids incidentally, mucobromic acid reacts with formamide to provide a useful synthesis of 5-bromopyrimidine. On the other hand, with control, methyl furoate can be cleanly converted into its 5-monobromo or 4,5-dibromo derivatives hydrolysis and decarboxylation of the latter then affording 2,3-dibromofuran bromination of 3-furoic acid produces 5-bromofuran-3-carboxylic acid. ... 

Mucochloric acid can be prepared by the oxidative chlorination of fur-furaldehyde (furfural), or from furan carboxylic acid and butynediol. 

Application GT-CAR is GTC s carboxylic acid recovery technology that combines liquid-liquid extraction technology with distillation to recover and concentrate carboxylic acids from wastewater. The GT-CAR process is economical for any aqueous stream generated in the production of dimethyl terephthalate (DMT), purified terephthalic acid (PTA), pulp/pa-per, furfural and other processes. 

This chapter provides an industrial perspective on several oxidation routes to new bio-based molecules. In particular, it focuses on the use of Co/Mn/Br catalyst systems in air oxidations, based on the Amoco Mid-Century catalyst system used for / r -xylene oxidation (also see Chapter 4), as an efficient methodology for the conversion of 5-(hydroxymethyl)furfural (HMF) and 5-(methoxymethyl)furfural (MMF) to 2,5-furandicarboxylic acid (FDCA) in Avantium s YXY process. In addition, other less-studied conversions, such as methyl levulinate (ML) to succinic acid (SA), lignin to a variety of aromatic and phenolic carboxylic acids, are discussed as well. 

It has been shown that synthetic zeolites such as ZSM-5 can be used to convert oxygenated compounds derived from biomass materials into hydrocarbons which can be used as fuels or chemicals feedstocks (1,2,3,4). However, the pyrolysis oils obtained from biomass materials by different thermal and thermochemical processes (5,6) showed poor hydrocarbon yields and high tar content when contacted over ZSM-5 zeolite catalysts at high temperatures (7,8). Since the pyrolysis oils are composed of a wide variety of oxygenated compounds such as cyclopentanone, cyclopentenone, furfural, phenol, carbohydrate and carboxylic acid derivatives (9,10) it is difficult to point out exactly which family of compounds is contributing more to the observed tar and to the rapid deactivation of the catalysts. Catalytic studies on model compounds which are usually found in the biomass pyrolysis oils are therefore primordial in order to determine the best catalytic system for the up-grading of pyrolysis oils to useful hydrocarbon products. The reactions of some phenolic, carbonyl and carboxylic acid derivatives over ZSM-5 catalysts are already... 

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