Lactic acid, formation constants with

Reeder and Rieger6 used ESR spectra to identify complex ions and to estimate formation constants for aqueous oxovanadium(iv) complexes with lactic acid, thiolactic acid, glycolic acid, and thioglycolic acid. Through the use of second-harmonic detection, which produces second-derivative spectra, the resolution was good enough that several of the individual species could be separately... 

The proposed mechanism assumes the formation of a cyclic complex between the reactive protonated PDC and lactic acid which undergoes C-C fission. The similarly retarded reactions of benzaldehyde and 4-nitrobenzaldehyde are second order in H+ ion. The decrease in rate with increasing dielectric constant of the solvent suggests a cation-dipole interaction. The proposed mechanism assumes the formation of a cyclic chromic ester between the hydrated benzaldehyde and the protonated PDC species, followed by C-H fission in the rate-determining step which is believed to feature a transition state with an electron-deficient reaction centre. " ... 

A number of simple carboxylic acids are known to be produced within the body, and so can be classed as endogenous ligands. Diacids such as fumaric, succinic, and malic acid are constantly synthesized and metabolized in cells during the Krebs cycle, whereas formic, oxahc, lactic, glutaric, and tartaric acid also play significant roles in biological processes (amino acids are discussed in Section 4.3). These endogenous linkers can be considered edible and have been extensively employed in MOF assembly—both transition metal and lanthanide formates with extended structures are commonplace, as well as... 

The effect of exchange of lactic, mandelic and sulfosalicylic acids on the relaxation of solvent protons gave rate constants (k) of exchange from 1.73 to 0.701 mol-1 s-1.642 Kinetics of complex formation with mandelic (HMDA) and vanillomandelic acids (HVMDA) gave rate constants (1.09 x 103 and 1.13 x 103 mol-1 s 1 for MDA- and VMDA ) consistent with a dissociative (Eigen) mechanism.438 As in the case of oxalic and malonic acids (Section 33.5.5.5.ii Table 27), species with coordinated hydroxyl are labilized. 

Most research supported the pH maintenance at 7.0 and some suggested pH maintenance at two different levels (6.3 and 7.0) to decrease the by-products formation (Ji et al., 2009). The forced pH fluctuation applied for 1,3-PD production was described (Petrov and Stoyanov, 2012). The method was realized by consecutive raisings of pH ranging from 1.0 to 2.0 between 2 and 4 hours during fed-batch fermentation. The maximal 1,3-PD concentration, productivity, and molar yield on glycerol increased by 10%, 22%, and 29% compared with constant pH under fed-batch conditions, respectively. In addition, the formation of by-products was significantly decreased, especially that of lactic and acetic acid. 

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