Fumaric acid method

Description of Method. Salt substitutes, which are used in place of table salt for individuals on a low-sodium diet, contain KCI. Depending on the brand, fumaric acid, calcium hydrogen phosphate, or potassium tartrate also may be present. Typically, the concentration of sodium in a salt substitute is about 100 ppm. The concentration of sodium is easily determined by flame atomic emission. Because it is difficult to match the matrix of the standards to that of the sample, the analysis is accomplished by the method of standard additions. 

Aqueous titration with IN sodium hydroxide is the usual malic acid assay. Maleic and fumaric acid are deterrnined by a polarographic method. Analytical methods have been described (40). 

Fumaric acid is used in the plastics industry, in the food industry and as a source of malic add. Although demand has increased rapidly over the last 30 years its production from fermentation has been totally replaced by a chemical method. It is now produced far more cheaply by the catalytic oxidation of hydrocarbons, particularly benzene. With the continuing uncertainties concerning the availability and cost of petroleum, however, fermentation may yet be a viable alternative. 

Examples of polyfunctional carboxylic acids esterified by this method are shown in Table I. Yields are uniformly high, with the exception of those cases (maleic and fumaric acids) where some of the product appears to be lost during work-up as a result of water solubility. Even with carboxylic acids containing a second functional group (e.g., amide, nitrile) which can readily react with the oxonium salt, the more nucleophilic carboxylate anion is preferentially alkylated. The examples described in detail above illustrate the esterification of an acid containing a labile acetoxy group, which would not survive other procedures such as the traditional Fischer esterification. 

The hydrogen transfer photosensitization has been applied to the diastereo-selective alkylation of chiral fumaric acid derivatives, where again the mild conditions of the photochemical method are advantageous (Figure 3.8). ... 

The reactions enumerated lead to the adducts that are observable by means of the ESR method. In the cases of maleic and fumaric acids, ESR spectra can be recorded at high enough pH values only Being a strong electrophile, radical SO4 is more active toward a carboxylate ion than to neutral molecules of unsaturated acids. 

One of these units is converted into a derivative A so that an enantiomeric mixture is generated which can be resolved in the usual manner. The desired enantiomer is used for the continuation of the synthesis, whereas the undesired one is recycled to the starting meso-compound. An illustration of this method is the synthesis of (/-biotin (9) from fumaric acid via the meso-intermediates 5/6 and the enantiomers 7/8 50. 

The main drawback in the use of fumaric acid is its slow solubility rate in compar ison with citric acid, and special methods need to be employed in its dissolution. It has been claimed that fumaric acid and its salts have a tendency to stabilise the suspended matter in both flash-pasteurised and frozen fruit concentrates (McColloch Gentile, 1958). 

Separation of the organic acids is also possible using an ion-exclusion column, such as a Bio-Rad HPX-87H. However, in this case it is essential that the acids are separated from the sugars otherwise a number of peaks co-elute, thus distorting the quantification. This method is particularly good for the analysis of fumaric acid in apple juice because no pre-treatment is required and the acid elutes late in the chromatogram, well separated from other components (Figure 10.7). 

Fumaric acid has been found to be a good marker to detect the addition of D,L-malic acid to apple juice (Junge Spandinger, 1982). With the advent of the enzymic assay procedure for D-malic acid the method fell out of use. However, in 1995, a number of samples of apple juice in Germany were found to contain elevated levels of fumaric acid, which was attributed to the addition of L-malic acid. 

As for the unsaturated carbonyl compounds, the most significant groups are the oc,/ -unsaturated acids or esters. Some of their methods of formation are closely analogous, for example, (a) the Horner-Emmons or Wadsworth-Emmons reaction, and (b) the aldol-type reactions. Rather more specific methods are considered below for the formation of a,/ -acetylenic acids, and for the conversion of the unsaturated dicarboxylic acid, maleic acid, into its anhydride or into fumaric acid. 

All these advanced methods have been compared with anodic oxidation for a 178-ppm 4-chlorophenol solution [140]. The mineralization rate was much faster for the new processes and the substrate was completely transformed into C02 by the Photoelectro-Fenton method, as can be deduced from data given in Fig. 22. In all cases, the initial intermediate was 4-chloro-l,2-dihydroxybenzene, which was further oxidized to yield maleic and fumaric acids with loss of Cl-. The subsequent degradation of these acids gave oxalic acid, which complexes with Fe(III). Such complexes are attacked slowly by OH, but decomposed quickly by UVA light. 

Those who wish to prevent the malo-lactic fermentation from occurring have had some success by maintaining a low pH, cleaning up the wine early, maintaining a high S02, and sterile filtering into the bottle. This is not 100 percent foolproof. Tchelistcheff et al. (23) reported on the use of fumaric acid as an inhibitor of the malo-lactic fermentation and this method is now being used with some success by a number of commercial wineries in California. 

The radical polymerization in aqueous solution of a series of monomers—e.g., vinyl esters, acrylic and methacrylic acids, amides, nitriles, and esters, dicarboxylic acids, and butadiene—have been studied in a flow system using ESR spectrometry. Monomer and polymer radicals have been identified from their ESR spectra. fi-Coupling constants of vinyl ester radicals are low (12-13 gauss) and independent of temperature, tentatively indicating that the /3-CH2 group is locked with respect to the a-carbon group. In copolymerization studies, the low reactivity of vinyl acetate has been confirmed, and increasing reactivity for maleic acid, acrylic acid, acrylonitrile, and fumaric acid in this order has been established by quantitative evaluation of the ESR spectra. This method offers a new approach to studies of free radical polymerization. 

Copolymerization with Vinyl Carboxylic Acids. The acids usually suggested for this method include maleic and fumaric acids and their half esters, crotonic, itaconic, methacrylic, and acrylic acid. The latter three appear to be most generally preferred. On occasion, the amides of these acids are suggested for achieving the same end result (24). Suggested specifically for butadiene-styrene latexes are these acids at about 0.05-10 wt. % based on total monomer. The latex should be adjusted to pH 8-11 (28, 29). For copolymerization with vinyl acetate (2) and acrylic monomers (18) identical acid monomers are suggested. Use of such latexes is claimed to give F/T stable emulsion floor polishes (25) and paints (16). 

Method of cyclisation Wislicenus was the first to suggest that an intramolecular reaction would take place easily if the reacting groups are on the same side of the double bond. Thus to find out the configuration of maleic and fumaric acids, we heat the two acids. Since the former forms the anhydride easily and not the latter, the former is cis while fumaric acid is trans. Also since the anhydride adds on water even at room temperature and is transformed back into maleic acid, there can be no doubt about the maleic acid being cis. 

The oxidation of 1,4-dicarboxylic acids with LTA in benzene results in double decarboxylation with the formation of a double bond (equation 16). Similarly, the pyrolysis of the di-r-butyl peroxy esters of 1,4-dicarboxylic acids in high boiling solvents leads to the formation of double bonds (equation 17). The method is especially useful in so far as 1,4-diacids are readily available from Diels-Alder reactions using derivatives of mtdeic and fumaric acid as the dienophile. Apparently, application of the 0-acyl thiohydroxamate method to 1,4-diacids does not result in the formation of double bonds but rather in the product of double decarboxylative rearrangement (Section S.4.6.1). ... 

The reverse of these reactions viz., the conversion of maleic and fumaric acids, by the addition of hydrogen bromide, into mono-brom succinic acid by the addition of two bromine atoms, into di-brom succinic acid and also by the addition of two hydrogen atoms, into succinic acid itself all show these same relations of maleic and fumaric acids to succinic acid and its bromine substitution products and establish the constitution of these isomeric di-basic unsaturated acids as given. The two acids may also be prepared from malic acid which is, in fact, the chief method by which they are prepared. This reaction will be considered later when malic acid itself is studied. 

German name, Trauben-saure, is derived from the word for grapes. It is probable that it does not exist in grapes as racemic acid but that it is formed from the dextro acid as this transformation can easily be effected by the action of acids or even by water alone. When tartaric acid is prepared synthetically from succinic acid, from glyoxal, or from malic, maleic or fumaric acids either racemic acid or meso-tartaric acid is always formed. That is, synthetic reactions result in the formation of an inactive form. The methods of splitting racemic acid into its optically active components has been fully discussed. The sodium-ammonium racemate is the only salt that is of importance. This has been spoken of in connection with the method of splitting racemic acid into its components.. Like the free acid this salt exists, in dilute solution, as equal molecular parts of the dextro and levo forms. Only in concentrated solution does it exist as the racemate itself. 

Many plants contain a variety of free acids such as acetic acid, citric acid, fumaric acid, malic acid, succinic acid, oxalic acid, glycohc acid, etc. They are components of citric cycle, whereas the others are intermediates in the pathway from carbohydrates to aromatic com-pounds. Following extraction, organic acids can be separated and detected with a variety of techniques. Thin layer chromatographic methods have been also employed to separate certain organic acids,as presented in Table 3. 

Dialkyl blsthioxooxalates are obtained if the sulfhydrolysis is performed in the presence of acetic acid (equation 50). The method also works successfully in the case of the homologous dicarboxylic acids (equation 51), 4 including the unsaturated fumaric acid. ° The preparation and further reaction of the appropriate imidates is not always straightforward. As Hartke and coworkers ° 4 have shown. 

Comes, J.E. and Beelman, R.B. 2002. Addition of fumaric acid and sodium benzoate as an alternative method to achieve a 5-log reduction of Escherichia coli 0157 H7 populations in apple cider. Journal of Food Protection 65 476-483. 

Method C (general procedure). The vicinal dibromide (1-2 mmol) and the diaryl ditel-Inride (1-2 mmol) are reflnxed in tolnene or HOAc for 1-4 h (1,2-dibromoethane is used neat). After cooling, the mixture is filtered to remove the Te (quantitative yield) and the diaryltellurinm dibromide is precipitated by addition of hexane. The alkene is obtained by evaporation of the filtrate (cinnamic and fumaric acids, both insolnble in petrolenm ether, are separated from the tellurium dibromide with EtOH). 

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