Benzoic acid

About: Benzoic acid is a research topic. Over the lifetime, 11832 publications have been published within this topic receiving 167127 citations. The topic is also known as: Retardex & E210.

Hydrogen Atom Abstraction by Permanganate: Oxidations of Arylalkanes in Organic Solvents.

Abstract: Oxidations of arylalkanes by nBu4NMnO4 have been studied in toluene solvent: toluene, ethylbenzene, diphenylmethane, triphenylmethane, 9,10-dihydroanthracene, xanthene, and fluorene. Toluene is oxidized to benzoic acid and a small amount of benzaldehyde; other substrates give oxygenated and/or dehydrogenated products. The manganese product of all of the reactions is colloidal MnO2. The kinetics of the reactions, monitored by UV/vis spectrometry, show that the initial reactions are first order in the concentrations of both nBu4NMnO4 and substrate. No induction periods are observed. The same rate constants for toluene oxidation are observed in neat toluene and in o-dichlorobenzene solvent, within experimental errors. The presence of O2 increases the rate of nBu4NMnO4 disappearance. The reactions of toluene and dihydroanthracene exhibit primary isotope effects: kC7H8/kC7D8 = 6 (±1) at 45 °C and kC14H12/kC14D12 = 3.0 (±0.6) at 25 °C. The rates of oxidation of substituted toluenes show only small substituent...

On the Inhibition of Muscle Membrane Chloride Conductance by Aromatic Carboxylic Acids

Abstract: 25 aromatic carboxylic acids which are analogs of benzoic acid were tested in the rat diaphragm preparation for effects on chloride conductance (G(Cl)). Of the 25, 19 were shown to reduce membrane G(Cl) with little effect on other membrane parameters, although their apparent K(i) varied widely. This inhibition was reversible if exposure times were not prolonged. The most effective analog studied was anthracene-9-COOH (9-AC; K(i) = 1.1 x 10(-5) M). Active analogs produced concentration-dependent inhibition of a type consistent with interaction at a single site or group of sites having similar binding affinities, although a correlation could also be shown between lipophilicity and K(i). Structure-activity analysis indicated that hydrophobic ring substitution usually increased inhibitory activity while para polar substitutions reduced effectiveness. These compounds do not appear to inhibit G(Cl) by altering membrane surface charge and the inhibition produced is not voltage dependent. Qualitative characteristics of the I-V relationship for Cl(-) current are not altered. Conductance to all anions is not uniformly altered by these acids as would be expected from steric occlusion of a common channel. Concentrations of 9-AC reducing G(Cl) by more than 90 percent resulted in slight augmentation of G(I). The complete conductance sequence obtained at high levels of 9-AC was the reverse of that obtained under control conditions. Permeability sequences underwent progressive changes with increasing 9-AC concentration and ultimately inverted at high levels of the analog. Aromatic carboxylic acids appear to inhibit G(Cl) by binding to a specific intramembrane site and altering the selectivity sequence of the membrane anion channel.

Hydroxylation reactions induced by near-ultraviolet photolysis of aqueous titanium dioxide suspensions

Abstract: Aqueous suspensions of titanium dioxide (anatase) containing benzoic acid or sodium benzoate have been illuminated with near-ultraviolet light under a variety of experimental conditions. In the presence of oxygen, o-, m- and p-hydroxybenzoic acids are formed in the same isomeric distribution found for OH-radical attack on benzoic acid. When OH-radical scavengers are present the yield of o-hydroxybenzoic acid is depressed. Ratios of rate constants evaluated on the basis of competition kinetics for the OH radical are in agreement with published rate constants. In the absence of oxygen the yield of the hydroxy compound is quite low, but high yields can be restored by the addition of iron(III). In oxygenated slurries, peroxides are formed in initial yield equivalent to about half the yield of total hydroxybenzoic acids. The addition of hydrogen peroxide to the slurries makes no significant difference to the yield of o-hydroxybenzoate. The results are consistent with the generation of OH radicals via the positive holes of the TiO2 particles, followed by OH-radical attack on the aromatic ring and subsequent oxidation of the hydroxy adduct with oxygen or iron(III) to give the corresponding phenol.