Succinic acid value chain

On the other hand, also two CO2 molecules may react with a different number of ethene molecules yielding for instance maleic acid, succinic acid, adipic acid or long-chain dicarboxylic acids. Also these products are either bulk or fine chemicals of high commercial value. 

Succinic acid is well established as a bio-based platform chemical and intermediate. The terminal carboxylic acid groups open up numerous possibilities for further processing. A major development is the polymerization of succinic acid with its hydrogenated diol product (1,4-BDO) to produce the biodegradable plastic, polybutylene succinate (Hendrik and Willie, 2014). The potential value chain of succinic acid is depicted in Fig. 9.6. 

FIGURE 9.6 Potential value chain of succinic acid. 

Fig. 3.1. A, The respiratory chain. Q and c stand for ubiquinone and cytochrome c, respectively. Auxiliary enzymes that reduce ubiquinone include succinate dehydrogenase (Complex II), a-glycerophosphate dehydrogenase and the electron-transferring flavoprotein (ETF) of fatty acid oxidation. Auxiliary enzymes that reduce cytochrome c include sulphite oxidase. B, Thermodynamic view of the respiratory chain in the resting state (State 4). Approximate values are calculated according to the Nernst equation using oxidoreduction states from work by Muraoka and Slater, (NAD, Q, cytochromes c c, and a oxidation of succinate [6]), and Wilson and Erecinska (b-562 and b-566 [7]). The NAD, Q, cytochrome b-562 and oxygen/water couples are assumed to equilibrate protonically with the M phase at pH 8 [7,8]. E j (A ,/ApH) for NAD, Q, 6-562, and oxygen/water are taken as —320 mV ( — 30 mV/pH), 66 mV (- 60 mV/pH), 40 mV (- 60 mV/pH), and 800 mV (- 60 mV/pH) [7-10]. FMN and the FeS centres of Complex I (except N-2) are assumed to be in redox equilibrium with the NAD/NADH couple, FeS(N-2) with ubiquinone [11], and cytochrome c, and the Rieske FeS centre with cytochrome c [10]. The position of cytochrome a in the figure stems from its redox state [6] and its apparent effective E -, 285 mV in...

Other bacteria are able to use as electron donors compounds that constitute the reduced components of redox systems with E g values more negative than that of the quinone/quinol redox system (E g - OV) which binds at the Qg site of BPS [Fig. 3(c)]. Examples of such electron donors are H2S (E g of S/ HgS = -0.23V), which is used by some purple sulfur bacteria (including the versatile Chromatium), and malic acid (E of oxaloacetate/malate = -0.17V), which is used by some purple- and green non-sufur bacteria. Organisms using such electron donors have an enzyme that catalyses the generalized reaction shown in eq. 2 this enzyme is the functional equivalent of the succinate UQ oxidoreductase of complex II of the mitochondrial electron transport chain. 

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