Succinic acid, Methylene

The constitution of ita-conic acid as methylene succinic acid is thus established. Di-basic acids which contain a triple bond and, therefore, related to propin-oic acid are known but will not be considered. 

Itaconic acid (methylene succinic acid) is an unsaturated five-carbon dicar-boxylic acid. It is a by-product of the destructive distillation of citric acid. The reaction leading to itaconic acid from citric acid is as follows ... 

Among the other reduced prochiral substrates, methylene succinic acid was hydrogenated with ee values up to 59 and 50% using respectively the catalysts Rh-3 [3] and Ru-BINAP (9) [21]. The hydrogenation of the /hketo ester 21 was also performed in water in the presence of ruthenium complexes associated with ligands 13 and 14 (Eq. 4) [24, 25] the hydroxy ester 22 was obtained with enantioselectivi-ties up to 94%. 

A rhodium complex with chiral phosphane ligand was also intercalated into sodium hectorite by cation exchange (Sento et al. ). The intercalated compound was characterized by FTIR, XRD, and TEM and the basal spacing of the compound was estimated to be 2.29 nm. This novel het-erogenized eatalyst exhibited a characteristic chiral as well as size recognition of the substrate molecule (like the "Tailor-made compounds" method used earlier by Balandin in the hydrogenation of tripticene derivatives over Ni) and was used in enantioselective hydrogenation of the itaconates (methylene-succinic acid esters). 

Others contain semi-rigid backbone structures as in the case of the itaconic acid (methylene succinic acid) (2). 

Also called methylenebutanedioic acid and methylene-succinic acid. 

Itaconic Acid (Methylene-succinic acid, pro-pytay -2 -dicarbozyUc acid)... 

Since polymerizations of maleic acid and various alkyl esters were mentioned earlier, the derivatives of maleic add discussed below are fumaric acid and dialkylfumarates, maleonitrile and fumaronitrile, maleimide and its N-substituted derivatives, and methylene succinic acid and its anhydride (itaconic anhydride). 

Merck and Company, Whitehouse Station, NJ, 2001). Also called Methylenebutanedioic Acid and Methylene-Succinic Acid. 

From the chemical point of view, succinic acid and its anhydride are characterized by the reactivity of the two carboxyUc functions and of the two methylene groups. Uses range from pharmaceuticals to food, detergents, cosmetics, plastics and resins, plant growth regulators, textiles, photography, and gas and water treatment. 

Succinic acid and anhydride undergo most of the reactions characteristic of dicarboxyhc acids and cycHc acid anhydrides, respectively. Other interesting reactions take place at the active methylene groups. 

Halogenation. Succinic acid and succinic anhydride react with halogens through the active methylene groups. Succinic acid heated in a closed vessel at 100°C with bromine yields 2,3-dibromosuccinic acid almost quantitatively. The yield is reduced in the presence of excess water as a result of the formation of brominated hydrocarbons. The anhydride gives the mono- or dibromo derivative, depending on the equivalents of bromine used. 

Several procedures for making glutaric acid have been described in Organic Syntheses starting with trimethylene cyanide (28), methylene bis (malonic acid) (29), y-butyrolactone (30), and dihydropyran (31). Oxidation of cyclopentane with air at 140° and 2.7 MPa (400 psi) gives cyclopentanone and cyclopentanol, which when oxidized further with nitric acid at 65—75° gives mixtures of glutaric acid and succinic acid (32). 

Convincing evidence for a surface erosion process is shown in Fig. 8, which shows the concomitant release of the incorporated marker, methylene blue, release of the anhydride excipient hydrolysis product, succinic acid, and total weight loss of the device. According to these data, the release of an incorporated drug from an anhydride-catalyzed erosion of poly (ortho esters) can be unambiguously described by a polymer surface erosion mechanism. 

FIGURE 8 Cumulative release of methylene blue (o), [1,4 - 14c] succinic acid (a), and polymer weight loss ( ) from polymer discs prepared from 3,9-bis(ethylidene-2,4,8,10-tetraoxaspiro[5,5Jundecane) and a 50 50 mole ratio of trans - cyclohexane dimethanol and 1,6-hexanediol at pH 7.4 and 37°C. Polymer contains 0.1 wt% [1,4 — [succinic anhydride and 0.3 wt% methylene blue. (From Ref. 

Butadiene-2,3-dicarboxylic acid Succinic acid, dimethylene- (8), Butanedioic acid, bis(methylene)- (9) (488-20-0)... 

HOOC CHj CH, C OOH + 2H 2CH,-C OOH These investigators have shown that suspensions of Aerobacier indologenes convert carboxyl-labelled acetate into isotopic succinate and vice versa. In both cases the isotope remained fixed in the carboxyl groups. Furthermore, doubly labelled acetate is converted to succinic acid which has the isotope equally distributed between the carboxyl and methylene groups. This is strong evidence that acetic acid can undergo condensation to form succinic acid without participation of carbon dioxide as an intermediate. 

A sufficient separation of all these compounds, therefore, is only achieved by using two AS4 columns in series. However, the separation of the two stereoisomers, maleic acid and fumaric acid, is much easier. It is obtained under standard conditions and is shown in Fig. 3-87. In contrast to monocarboxylic acids, the retention of aliphatic dicarboxylic acids increases with decreasing pK value. The corresponding data are summarized in Table 3-20. This finding is explained by the charge-stabilizing effect exerted by the +1-effect of the methylene groups which decreases from succinic acid to oxalic acid ... 

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