Benzoic acid/benzoate

After reaction of 6-14C-DON with glutaminase, glutamic acid (1 equivalent) and I4C-methanol (0.75 equivalent) were isolated from the reaction mixture. The initial product formed from the C-6 atom appears to be diazomethane Ha). If relatively high concentrations of a benzoic acid-benzoate buffer are included in the reaction mixture, labeled methyl benzoate is formed in addition to the methanol. Further, the relative... 

FOLLOW-UP PROBLEM 19.2 How would you prepare a benzoic acid-benzoate buffer with pH = 4.25, starting with 5.0 L of 0.050 M sodium benzoate (CgHsCOONa) solution and adding the acidic component of benzoic acid (CgHsCOOH) is 6.3X10 . ... 

Aromatic compounds containing alkyl side chains are metabolized using three general strategies, illustrated in Figure 5. The first involves oxidation of the alkyl side chain toluene is oxidized to benzyl alcohol, and then further oxidized to benzaldehyde and benzoic acid. Benzoate dioxygenase then converts benzoate directly to catechol, via the corresponding air-diol. 

Benzoic acid has long been considered to be formed by benzaldehyde oxidation in the presence of oxygen, but was not bebeved to form under anaerobic conditions [95]. Here, when the reaction was performed under anaerobic conditions, benzoic acid was not detected in the effluent by gas chromatography (GC) analysis, but in situ ATR-IR spectra clearly showed its presence as an adsorbed benzoate species, indicated by bands at 1600, 1546,1422, and 1393 cm [94]. The fact that benzoate species are detected on the catalyst surface, but not in the effluent, suggests that these species are very strongly bound possibly at basic sites on the AljOj support The formation of benzoic acid/benzoate under anaerobic conditions was speculated to result from hydration of benzaldehyde via a germinal diol, followed by a dehydrogenation. This pathway is summarized as follows ... 

Benzoic acid and sorbic acid can both be extracted using modified Monier Williams distillation methods and quantified spectrophotometrically, or in the case of benzoic acid, by thin-layer chromatography. LC and GLC methodologies are available and routinely used, having the advantage of simultaneous quantification of both benzoic acid/benzoates and sorbic acid. 

You are asked to make a buffer with a pH value close to 4 that would best resist an increase in pH. You can select one of the following acid-conjugate base pairs acetic acid-acetate. Kg = 1.8 x 10 ammonium ion-ammonia. Kg = 5.6 X 10 ° or benzoic acid-benzoate, Kg = 6.3 x 10 and you can mix them in the following acid-conjugate base ratios 1 1, 2 1, or 1 2. What combination would make the best buffer ... 

The chemistry of extraction frequently involves nonlinear equihbria between the raffinate and extract. This reflects the extraction chemistry, which is often more com-phcated than that for absorption or dilute distillation. The nonlinear equilibria frequently result from specific chemical reactions. For example, benzoic acid can be extracted from water into benzene. The benzoic acid in water can ionize to form a mixture of benzoic acid, benzoate anions, and protons. Benzoic acid in benzene can dimerize. The ionization and dimerization may result in an equihbrium that is nonlinear and strongly dependent on concentration, pH, and temperature. 

---