54-21-7Relevant articles and documents
Rate constants for reaction of hydroxyl radicals with sulfapyridine and aminosalicylic acids
Motohashi, Noriko,Saito, Yutaka
, p. 163 - 166 (1996)
Sulfasalazine, an anti-inflammatory drug, is metabolized to sulfapyridine and 5-aminosalicylic acid (5-ASA) which is therapeutically active. In the inflammation, active oxygen species have been suggested to play an important role. Among various active oxygen species, hydroxyl radical is known to be the most active radical. To elucidate the reactivity of sulfapyridine, 5- ASA, 4-ASA and 3-ASA with hydroxyl radicals, the rate constants were determined measuring the fluorescence of hydroxybenzoates induced by radiolysis hydroxylation of benzoate. The constant for 5-ASA, strongly fluorescent but insoluble in ether, was measured after ether extraction of hydroxybenzoates under acidic condition. For the other compounds, the rate constants were determined using a method which separates hydroxybenzoates by HPLC after the ether extraction, since the three compounds moved to the ether layer and interfered with the fluorescence of the hydroxybenzoates induced. Four rate constants were obtained in the range of 6.4-7.0 x 109 M-1 s- 1, showing that they similarly scavenge hydroxyl radicals in vitro.
Synthetic method of methyl salicylate
-
Paragraph 0016-0017; 0020-0021; 0024-0025, (2021/02/10)
The invention discloses a synthesis method of methyl salicylate. The method comprises the following steps: preparing sodium phenolate by using caustic soda flakes and phenol as raw materials, carryingout carboxylation reaction on the obtained sodium phenolate and carbon dioxide gas to obtain sodium salicylate, reacting the obtained sodium salicylate with chloromethane gas under the action of a phase transfer catalyst to obtain a crude methyl salicylate product containing a toluene solvent, neutralizing and washing the crude methyl salicylate product, recovering the toluene solvent at normal pressure, and carrying out vacuum distillation to obtain a finished methyl salicylate product. According to the method, a strong acid catalyst is not used, so that the wastewater amount is greatly reduced, and the corrosion to equipment and the pollution to the environment are reduced. According to the method, equipment is not seriously corroded, the wastewater amount is small, and the process is more environmentally friendly.
Evidence of co-operativity in the pre-micellar region in the hydrolytic cleavage of phenyl salicylate in the presence of cationic surfactants of CTAB, TTAB and CPC
Sen, Pratik K.,Chatterjee, Piyali,Pal, Biswajit
, p. 23 - 30 (2015/02/18)
The effects of cationic surfactants of cetyl trimethyl ammonium bromide (CTAB), tetradecyl trimethyl ammonium bromide (TTAB) and cetyl pyridinium chloride (CPC) on the kinetics of intramolecular general base catalyzed hydrolysis ([OH-] range 0.05-0.1 mol L-1) of phenyl salicylate have been studied at different temperatures. The rate is independent of [OH-] in the studied range. The anionic surfactant sodium dodecyl sulphate (SDS) has no effect on the rate. The presence of small amount of any of these cationic surfactants well below its critical micelle concentration markedly inhibits the rate of reaction suggesting a pre-micellar aggregation between the substrate and surfactant monomers. The kinetic data have been analyzed in terms of earlier reported models (Piszkiewicz's co-operativity model and Raghavan and Srinivasan's model) for micellar catalysis. The binding constants between the substrate and the surfactants evaluated from the two models are in good agreement. Three dimensional structure of the pre-micellar aggregate controls the approach of the nucleophile water molecule to the reaction center. The planar structure of the pyridinium head group of CPC provides less steric hindrance to the attacking water molecule that leads to the least enthalpy of activation for CPC among the three surfactants. The association between the negatively charged substrate and the cationic surfactant is favored owing to electrostatic as well as hydrophobic interactions. The binding between the substrate and pre-micelles follows the order: CPC > TTAB > CTAB.