Acid continued succinic

Nitrocyclohexane has been prepared by E. I. du Pont de Nemours Company by nitration of cyclohexane. Cyclohexane undergoes nitration and oxidation to give nitrocyclohexane and adipic acid along with smaller amounts of glutaric acid and succinic add. Nitration is accelerated by the addition of nitrogen dioxide. The process may be operated continuously in the liquid phase with 45-75 per cent nitric acid at temperatures of 100-200 C and pressures of 2-10 atm. This process is of particular interest in that oxidation products from cycloalkanes are usually S3rmmetrical di-carboxylic acids, which are of industrial importance. 

Urbance, S.E., Pometto, A.L. Ill, DiSpirito, A.A., and Denli, Y. (2004) Evaluation of succinic acid continuous and repeat-batch biofilm fermentation by Actinobacillus succinogenes using plastic composite support bioreactors. Appl. Microbiol Biotechnol, 65, 664-670. 

Electrochemical membrane reactors have also been used in fine chemistry reactions. The electrochemical reduction of maleic acid to succinic add has been reported by using a sulfonated poly(styrene divinylben-zene) membrane intercalated between copper and lead anodes, assembled in a continuous contactor-type membrane reactor. Montiel et al. have recently described the use of MEA technology for the synthesis of N-acetyl-L-qrsteine by electroreduction of N,N-diacetyl-L-qrstine. 

Table 3 summarizes many of the uses mentioned in the literature. The main use of succinic acid in Japan is for bath preparations (314—322). This application in 1994 accounted for nearly 80% of total consumption. After recording a more than 10% yearly increase in the late 1980s, the growth of this apphcation has slowed down, and consumption is decreasing on account of the replacement of succinic acid by fumaric acid for economic reasons. This trend is expected to continue in the coming years. 

This process, to which the raw materials are suppHed at low pressures, is continuous and gives good yields of acrylates (see Acrylic acid and derivatives). In the presence of catalytic amounts of Co2(CO)g, acetylene has been carboxylated in methanol yielding dimethyl succinate as the principal product (135). 

Two hundred and seventy-six grams (94.3 cc., 1.72 moles) of bromine (Note 7) is now added as rapidly as possible through the dropping funnel, the rate of addition being so controlled that the Friedrichs condenser is continuously about half full of the refluxing liquid (Note 8). This operation takes about one hour (Note 9). After about 100 g. of bromine has been added, the dibromo-succinic acid forms rapidly and separates in tiny white needles. At the completion of the reaction there should be a slight excess of bromine, as indicated by the red color of the solution. Occasionally 5-10 g. of bromine has to be added at this point to insure an excess. 

The case of succinic acid cannot be discussed in terms of Coulombic interactions alone. Here, conformational changes induced by the binding process can contribute significantly to the correlation. Note also that g(l, 1) [or W(l, 1)] of succinic acid is not an average of the correlations in maleic and fiimaric acids. This could be partially due to the configurational changes in the succinic acid, induced by the binding process. We shall discuss below a simple two-state model for succinic acid, and a continuous model in the next subsection. 

Figure 4.28. The skeleton model for succinic acid, P-alanine, and ethane diamine. The model is essentially the same as that described in Fig. 4.27. Instead of a two-state model, we allow a continuous range of variation, 0 < > 2it. Also, and can be either negative or zero for a carboxylate or an amine group, respectively.

The buffering ranges of a weak electrolyte are only discrete if the pA a values of its acidic and/or basic groups are separated by more than 2 pH units. Some acids have ionisable groups with pKa values less than 2 pH units apart so that they produce buffers with wide ranges. For example, succinic acid, which has pA"a values of 4.19 and 5.57, can be considered to have a continuous buffering range between pH 3.19 and 6.57. 

A mixture of 118 g. (1 mole) of succinic acid, 188 g. (2 moles) of phenol, and 138 g. (83 ml., 0.9 mole) of phosphorus oxychloride (Note 1) is placed in a 2-1. round-bottomed flask fitted with an efficient reflux condenser capped with a calcium chloride tube (Notes 2 and 3). The mixture is heated on a steam bath in a hood (Note 3) for 1.25 hours, 500 ml. of benzene is added, and the refluxing is continued for an additional hour. The hot benzene solution is decanted from the red syrupy residue of phosphoric acid and filtered by gravity into a 1-1. Erlenmeyer flask. The syrupy residue is extracted with two 100-ml. portions of hot benzene, which are also filtered into the Erlenmeyer flask. The combined benzene solutions are concentrated to a volume of about 600 ml. (Note 4), and the pale yellow solution is allowed to cool, whereupon the diphenyl succinate separates as colorless crystals. It is filtered with suction on a Buchner funnel, washed with three 50-ml. portions of ether, and dried on a porous plate at 40°. The yield of diphenyl succinate, m.p. 120-121°, is 167— 181 g. (62-67%) (Note 5). 

Since in the citric acid cycle there is no net production of its intermediates, mechanisms must be available for their continual production. In the absence of a supply of oxalacetic acid, acctaic" cannot enter the cycle. Intermediates for the cycle can arise from the carinxylation of pyruvic acid with CO, (e.g., to form malic acid), the addition of CO > to phosphcnnlpyruvic acid to yield oxalacetic acid, the formation of succinic acid from propionic acid plus CO, and the conversion of glutamic acid and aspartic acid to alpha-ketoglutaric acid and oxalacetic acid, respectively. See Fig. 3. 

It may also be economical to remove the inhibitory product directly from the ongoing fermentation by extraction, membranes, or sorption. The use of sorption with simultaneous fermentation and separation for succinic acid has not been investigated. Separation has been used to enhance other organic acid fermentations through in situ separation or separation from a recycled side stream. Solid sorbents have been added directly to batch fermentations (18,19). Seevarantnam et al. (20) tested a sorbent in the solvent phase to enhance recovery of lactic acid from free cell batch culture. A sorption column was also used to remove lactate from a recycled side stream in a free-cell continuously stirred tank reactor (21). Continuous sorption for in situ separation in a biparticle fermentor was successful in enhancing the production of lactic acid (16,22). Recovery in this system was tested with hot water (16). 

These results show that sorption is a technical possibility for succinic acid separation. In particular, sorption remains an excellent candidate for in situ separation. However, targets for capacity, regeneration, and concentration were not met in these preliminary studies. Additional process tests focusing on regeneration and succinic acid concentration will be required. Therefore, these and other economic considerations not reported here have favored membrane or crystallization methods such as described in the referenced patents (3,26-28) these approaches were continued in the larger succinic acid fermentation project (29,30). The sorption data are presented as a baseline for other researchers in the examination of organic acid separation schemes. 

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