Organic acid fumaric acid

Figure 17-10. Weak organic acids formic acid, fumaric acid, and sulfamic acid.

Starch Amy lose Amylopectin Proteins Organic acids Citric acid Malic acid Succinic acid Fumaric acid Minerals... 

The oxidation of phenol on a platinum anode was studied by the same author [34]. At a current density of 50mA/cm, 70°C, and a pH of 3, the initial phenol concentration of 21 mmol/dm completely disappeared in 2 h. Apart from CO2, other organic intermediates such as hydroquinone, benzoquinone, maleic acid, fumaric acid, and oxalic acid were identified. An analysis of the reaction intermediates and a carbon balance showed that the destruction reaction occurred by two parallel pathways chemical oxidation with electrogenerated hydroxyl radicals, and direct oxidation of phenol and/or its aromatic intermediates to CO2. 

The organic acids maleic acid and fumaric add are cis-trans or Z- isomers (see diagram below), while cinnamaldehyde—responsible for the odour of cinnamon—occurs in the trans or form only. 

The manufacture of alkyd resins (qv), which are obtained by the reactions of polybasic acids or anhydrides, polyhydric alcohols, and fatty oils and acids, consumes about 17% of the phthahc anhydride demand. While materials such as maleic anhydride, isophthahc acid, and fumaric acid can also be used, phthahc anhydride is the most important. The resin provides a binder for coatings that are apphed for either protection or decoration. Ak quahty concerns have put alkyd resins under pressure from water-based coatings which do not emit organic vapors upon drying. 

In 1932 Krebs was studying the rates of oxidation of small organic acids by kidney and liver tissue. Only a few substances were active in these experiments —notably succinate, fumarate, acetate, malate, and citrate (Figure 20.2). Later it was found that oxaloacetate could be made from pyruvate in such tissues, and that it could be further oxidized like the other dicarboxylic acids. 

Fumaric acid is used as a flavoring, because it is the sourest tasting of the organic acids. Three parts of fumaric acid are as sour as five parts of citric acid. 

The effect of some organic acids on the exchange in perchlorate media has been investigated Fumaric , benzoic and o-phthalic acids have been shown to cause little or no alteration in the rate, whereas acetic, succinic, carbolic, oxalic and tartaric acids have an accelerating influence. The isotopic method ( Fe) and the 2,2 -dipyridyl separation have been used. The rate law observed was ... 

An important problem in emulsified organic-aqueous systems is that of scale-up, which is concerned with the realization of stable emulsions and the separation of phases after the reaction. The use of biphasic membrane systems that contain the enzyme and keep the two phases separated is likely to solve this problem. In the case of 5-naproxen an ee of 92% has been demonstrated without any decay in activity over a period of two weeks of continuous operation. A number of examples of biocatalytic membrane reactors have been provided by Giorno and Drioli (2000) and include the conversion of fumaric acid to L-aspartic acid, L-aspartic acid to L-alanine, and cortexolone to hydrocortisone and prednisolone. 

CE is widely used for separation and quantification of organic acids (Stover, 1997). Many CE studies were performed to quantify organic acids in some food matrices (Erazier, 2001 Galli et al., 2003 Klampfl et al., 2000 Lindeberg, 1996). Many small organic acids can be well separated with CE (Boden et al., 2000 Mato et al., 2006a,b Navarrete et al., 2005). Those acids include acetic, citric, fumaric, lactic, maleic, malic, oxalic, pyruvic, succinic, and gluconic acids which can be separated by CE in a short time. 

Organic compounds such as lactic acid [74, 75], citric acid [74], fumaric acid [76, 77], and amino acids [74] were also shown to catalyze the ROP of lactones, using alcohols and amines as initiators. Interestingly, an acid catalyst can be supported on a solid support such as porous silica [78]. Unfortunately, the polymerization is slow and reuse of the catalyst after its recovery and regeneration turned out to be unsuccessful. Finally, it is worth noting the particular behavior of amino acids, which are able to both catalyze and initiate the ROP of lactones [79]. 

Photolysis [KINETTCMEASUREMENTS] (Vol 14) maleic anhydnde [MALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) of molybdenum compounds [MOLYBDENUM AND COMPOUNDS] (Vol 16) of pesticides [SOIL CHEMISTRY OF PESTICIDES] (Vol 22) of silanes [SILICON COMPOUNDS - SILANES] (Vol 22) of titanium compounds [TITANIUM COMPOUNDS - ORGANIC] (V ol 24)... 

According to the food laws and regulations of the Food and Drug Administration (FDA), organic acids can be used as acidulants (e.g., citric, fumaric, malic, and sorbic acid), antimicrobial additives (e.g., propionic acid), and sequestrants (e.g., tartaric acid) (14). Most fatty acids of... 

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). 

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