Benzoic acid degradation rate

Lepidocrocite (-y-FeOOH) has also been used as a catalyst for Fentonlike reactions [54]. First-order decomposition of hydrogen peroxide was observed in the presence of this catalyst. Peroxide decay at 20 g/L catalyst was found to be pseudo-first-order and pH-dependent, with rate constant values reported from 0.102 hr-1 at pH 3.3 to 0.326 hr-1 at pH 8.9. In this system benzoic acid degradation was fastest at the low pH value. Under these conditions, acid dissolution of the lepidocrocite was observed to produce... 

Soil. In unsterilized soils, 58% of C-labeled sulfometuron-methyl degraded after 24 wk. Metabolites identified were 2,3-dihydro-3-oxobenzisosulfonazole (saccharin), methyl-2-(amino-sulfonyl) benzoate, 2-aminosulfonyl benzoic acid, 2-(((aminocarbonyl)amino)sulfonyl) benzoate, and [ C]carbon dioxide. The rate of degradation in aerobic soils was primarily dependent upon pH and soil type (Anderson and Dulka, 1985). The reported half-life in soil was approximately 4 wk (Hartley and Kidd, 1987). 

A typical example of HPLC method development and validation was provided by Boneschans et al. [9]. They developed an HPLC method for piroxicam benzoate and its major hydrolytic degradation products, piroxicam and benzoic acid. The authors utilised a robust stationary phase (Phenomenex Luna, Cig), with an optimised mobile phase comprising of acetonitrile/water/acetic acid (45/7/8 v/v), and a flow rate of 1.5 ml/min. The operating pH of the mobile phase (pH 2.45) was selected on the basis that it is ca. 2 pH units from the pKa of the drug, and hence reasonably insensitive to changes in mobile-phase preparation. The injection volume was 20 pi with a detection wavelength of 254 nm. They utihsed... 

This beneficial effect was attributed to rate enhancements of reduction processes. With benzoic acid, total degradation of the ring to CO2 occurred and the detection of salycilic acid suggested the intervention of 0H° radicals (56). These radicals were also proposed to explain the oxidation of n-Cx alkanes (x = 6,7,9,10) and of cyclohexane in 1 1 vol. water ydrocarbon two-phase mixtures over 10 wt °l Pt/Ti02 Traces of alcohols (and of 2-, 4-, 5-decanone with decane) were detected. No transformation occurred without O2 and in the absence of H2O the rate was substantially decreased. The role of Pt was attributed to a greater ease of oxygen reduction however the oxidation rate was only decreased by a factor of about 1.5 without Pt (59). 

Figure 7.18 Optimization of the separation of bopindolol (2), its precursor (3), and benzoic acid (1) as a degradation product within 30 min. Conditions carbon dioxide, 20% methanol, 20 mM TBA, 20 mM acetic acid flow rate, 4 ml/min. Column diol, 10 pm (100 mm x 4.6 mm ID). [Reprinted from Ref. 31, J. Chromatogr. 500, 469 (1990), with, kind permission of Elsevier Science Publishers, The Netherlands.]...

D Hennezel et al. [203] proposed a possible degradation pathway for the photo oxidation of gaseous toluene (Scheme 6). Their work was carried out over water and used TiC>2 which had been pre-treated with HC1 as it has been shown that this pre-treatment enhanced the removal rate of the toluene. Using GC-FIC, GC-MS and HPLC-UV they found that the intermediate products formed were benzoic acid, benzaldehyde and benzyl alcohol with trace derivatives of these products and of toluene that were nonhydroxylated on the ring. 

Figure 3 Degradation rate (mmol g -cat min ) of benzoic acid for different catalyst...

Figures Degradation rate (mmol g -cat min ) of benzoic acid for different catalyst loading without external circulation. Experimental conditions Cso = 0.2mM, pH = 3.7 3.9,7 = 303 K, / = 8.0 mW cm and O2 saturated (Mehrotra et al., 2005).

Is this mechanism, the copper acts as a redox catalyst Various initiators are combined with it to catalyze the hydrolysis, including magnesium benzoate, or salts of different metals (Li, Na, K, Ba, Co, etc.. The main side reactions arc4he decarboxylation of benzoic acid to benzene, or its complete degradation, and the production of diphenyl ether and tars. These tars, produced essentially at the expense of phenol, mainly appear in the liquid phase. They slow down its rate of formation considerably, and make it necessary to extract the reaction medium as rapidly as possible ... 

The aliphatic-aromatic diacid monomers were prepared from the reaction of bromoalkanoic acid methyl ester and p-hydroxy benzoic acid methyl ester. The polymers of carboxyphenoxy alkanoic add of n = 3, 5, and 7 methylenes were soluble in chlorinated hydrocarbons and melted at temperatures below 100 °C. Copolymers of these monomers melted at lower temperatures than the respective homopolymers. These polymers displayed zero-order hydrolytic degradation profile ranging from 2 to 10 weeks. Increasing the length of the alkanoic chain, decreased the degradation rate of the polymer (Fig. 3). 

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