Fumeric acid

Step two of the analysis is performed when the yellow color has disappeared. Here dilute sodium hydroxide solution R is added dropwise, and an intense blue color is produced caused by a complex between the dihydrox-fumeric acid and the iron(III) ions. No structure of this complex has apparently been published. It is different from the general complexes normally formed between the aliphatic dihydroxy carboxylic acid wi iron(III), since they are often yellow or violet and have an optimum in the pH region below neutrality. One could suspect that an enolization of the dihydroxfumeric acid is responsible for the blue colored complex. 

Polyesters are macromolecules made by reacting a diacid or dianhydride with a dihydroxy compound (diols). To make unsaturated polyesters, maleic anhydride or fumeric acid is used in addition to a saturated acid, which provides unsaturation in the structure. The most commonly used anhydrides are maleic anhydride (unsaturated) and phthalic anhydride (saturated). The commonest diols are ethylene glycol or propylene glycol. Use of an unsaturated anhydride is very critical to provide unsaturation in the structure, which is utilised to cure the resin by free-radical polymerisation. The chemical reaction for the synthesis of UPE is shown in Figure 2.13. 

BPA fumarate resins are prepared by the reaction of propoxylated BPA with fumeric acid. The use of BPA results in a significant reduction in the number of ester linkages and makes the resin comparatively non-polar. This resin therefore shows very good corrosion resistance and chemical resistance. BPA fumerate resin-based composites... 

Copolymerization. Vinyl chloride can be copolymerized with a variety of monomers. Vinyl acetate [9003-22-9], the most important commercial comonomer, is used to reduce crystallinity, which aids fusion and allows lower processing temperatures. Copolymers are used in flooring and coatings. This copolymer sometimes contains maleic acid or vinyl alcohol (hydrolyzed from the poly(vinyl acetate)) to improve the coating s adhesion to other materials, including metals. Copolymers with vinylidene chloride are used as barrier films and coatings. Copolymers of vinyl chloride with maleates or fumerates are used to raise heat deflection temperature. Copolymers of vinyl chloride with acrylic esters in latex form are used as film formers in paint, nonwoven fabric binders, adhesives, and coatings. Copolymers with olefins improve thermal stability and melt flow, but at some loss of heat-deflection temperature (100). Copolymerization parameters are listed in Table 5. 

To solve this problem we can first note the four ATP equivalents consumed in the biosynthesis of one urea from two amino acids. But the fumerate produced must be taken back to regenerate the oxalacetate used to pick up the nitrogen from one amino acid) ... 

Fumer, G., Westall, J. C., and Sollins, P. (1990) The Study of Soil Chemistry Through Quasi-steady State Models II. Soil Solution Acidity, Geochim. Cosmochim. Acta 54(9), 2363-2374. 

Stereospecificity may also apply to enzymes acting on the substrates containing double bonds, which give rise to geometric isomers, cis and trans or E and Z. For example, fumerase specifically catalyzes trans hydration of fumerate (trans-butenedioic acid) ... 

It is, however, better known that flavoenzymes (i.e., enzymes utilizing the flavin adenine dinucleotide [FAD FADH2] redox system) mediate the introduction of a,P carbon-carbon double bonds into carboxylic acids and into acetyl Coenzyme A (acetyl CoA) thioesters of long-, medium-, and short-chain fatty acids. In carboxylic acids, such as those of the tricarboxylic acid (citric acid, TCA, or Krebs) cycle (Chapter 11) the oxidation is affected by the enzyme sucdnate dehydrogenase (fumerate reductase— EC 1.3.99.1), which utilizes the cofactor flavin adenine dinucleotide (FAD) The latter is reduced to FADH2 and an ( )-double bond is introduced. The process shown in Scheme 9.105, for the conversion of succinate (1,4-butanedioic acid) to fumerate [(E)-l,4-butenedioic acid], is a fragment of the tricarboxylic acid (citric acid, TCA, or Krebs) cycle (Chapter 11), which is the pathway commonly utilized for oxidative degradation of acetate to carbon dioxide. 

The esters of maleic acid can be hydroformylated to obtain the formyl derivative 8. Adkins and Kresk reported the reaction of diethyl fumerate 7. In the presence of a cobalt catalyst at 150°C and a total pressure of 4 800 psi of carbon monoxide and hydrogen (2 1) CO Hi, the Oxo product, diethyl formylsuccinate 8 (R = Et), was formed in a 51% yield. The fate of the remaining material was not specified but it is believed to have mostly converted to diethyl succinate by hydrogenation (see below). 

Figure 3.20 shows a pyrogram of polymethylmethacrylate copolymerised to contain 1 and 10% of acrylic or methacrylic acid. By this procedure, copolymerised acrylic or methacrylic acid has been identified in terpolymers with (a) butyl acrylate and styrene, (b) methylmethacrylate and ethyl acrylate and, (c) ethylene and propylene. A methyl methacrylate - methylstyrene - maleic acid terpolymer, when examined by this propylation - pyrolysis procedure, yielded dipropyl fumerate and a smaller amount of dipropyl maleate. 

Styrenated fatty acids and alkyd resins spectrophoto-metric analysis using a modified Kappelmeier procedure, with ultraviolet determination of polymerized styrene Styrene and fumerate in esters and resins 0.1-2% styrene in polystyrene at 250-260 m/i direct determination polystyrene in a copolymer in chloroform solution at 269 mu partial separation, nitration, and determination as neutralized p-nitrobenzoic acid, of bound styrene in raw and cured polymers, using a three-wavelength ultraviolet measurement to check for unexpected interfer-... 

Tacticity studies have been conducted on poly(3-methyl-l-butene) [120], poly(p-isopropyl-a-methyl styrene) [121], a-methyl styrene [122], polytetrafluoroethylene [123], polyacrylic acid [124], polymethylvinyl ethers [125], polyacrylonitrile [126, 127], polyvinyltrifluoro acetate [128], polyvinyl alcohol and its ethers [129, 130], isobutene-maleic anhydride [111], isobutene dimethyl fumerate [131], isobutene dimethyl maleate [131], polyacrylonitrile [127], ethylene - vinyl acetate [132-135], polyalkyl vinyl ethers [136, 137], ethyl-2-chloroacetate [133], poly-trans-1,3-pentadiene [138], isotactic-l-butene - propylene [139], butadiene - propylene [140], polybutene [141], polychloroprene [142], ethylene - vinyl chloride [143], chlorinated polyethylene [144, 145], poly-a-methyl styrene [146], styrene acrylic acid [147], a-methyl styrene - methacylonitrile [148], styrene acrylonitrile [149], styrene isobutene [150], poly(p-fluoro-a-methyl styrene) [151], polyarylamide-6 [152], PP - polyamide-6 [152], polystyrene oxide [153], polybutene [154], atraconic anhydride - p-chlorostyrene [155], styrene - maleic anhydride [156, 157], ethylene - vinyl acetate [158], polymethyl vinyl ether [159], propene - carbon monoxide [160], methyl(3,3,3-trifluoropropyl)siloxane [161], poly(diallyldimethyl ammonium chloride) [162], polypropene [163, 164], polyepichlorohydrin [165], maleic anhydride-p-chlorostyrene [166], polymethacrylonitrile [167] and polyvinyl acetate [168]. 

As stated earlier, the growth of GC methods for the separation of organic acids has been dependent on the development of suitable derivatives and many of the problems have centred around difficulties in derivatization methods. Without the use of definitive identification from mass spectrometry, many workers have laboured in an effort to prove the nature of particular peaks and to understand the presence of additional peaks. This is especially true with regard to methylation methods which are known to give rise to multiple products and artefacts in some cases. Luke et al. (1963) reported the isomerization of dimethyl fumerate to dimethyl maleate, although McKeown and Read (1965) suspected that this was not isomerization but was due to formation of 4,5-dicarbomethoxypyrazoline. Derivatization difficulties have been paramount in the analysis of oxo acids (e.g. Simmonds et al, 1967 Alcock, 1969) (see Chapter 3). 

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