Hazard evaluation for redox system of cumene hydroperoxide mixed with inorganic alkaline solutions

In petrochemistry, dicumyl peroxide (DCPO) is used in various resins for improving physical properties, which was produced by cumene hydroperoxide (CHP) with oxidization reaction, redox reaction, and dehydration reaction. The reactant, CHP, is a typical organic hydroperoxide and has been intrinsically unstable and reactive due to its bivalent -O-O- structure which can be broken readily with bond-dissociation energy. This sequence on sensitive study aimed at the thermal hazard evaluation for the reactive and incompatible characteristics of CHP mixed with various inorganic alkaline solutions. Differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2) were used to analyze the thermal hazards and runaway reaction of redox system, such as decomposition of CHP in cumene solution and CHP react with inorganic alkaline solutions, exothermic onset temperature, peak power, heat of decomposition of dynamic scanning tests, adiabatic self-heating rate, pressure rise rate, maximum temperature, maximum pressure of reaction system, etc. The results of the tests have proven helpful in establishing safe handling, storage, transportation, and disposal guidelines.     

高效非硅氧漂稳定剂DQ05的性能及其应用

制备了一种新型的非硅氧漂稳定剂DQ05，并与硅酸钠对双氧水的稳定效果进行了对比．中试结果表明，DQ05在棉织物的冷轧堆漂白工艺中，其稳定效果接近传统的硅酸钠稳定剂；漂白后的产品白度、撕破强力均优于硅酸钠-双氧水漂白工艺的水平，是一种理想的氧漂稳定剂，有良好的应用前景。     

Effect of CH3OOH on the atmospheric concentration of OH radicals

Methyl hydroperoxide (CH₃OOH, MHP) is known to be a significant sink and reservoir of HO_x and RO_x radicals in the atmosphere. In order to investigate the impact of MHP on the concentration of atmospheric OH radicals, two key gas-phase reactions of MHP, i.e. the reactions with OH radicals and with UV photolysis, have been simulated at temperature of 293±2 K and total pressure of 1.01×10⁵ Pa, using the long path Fourier transform infrared (LP-FTIR) spectrometry. OH radicals are generated by the photolysis of O₃ in the presence of water vapor. Combined with the relative rate method, the reaction rate constant of MHP with OH radicals is determined to be (3.99±0.15)×10^-12 cm³?molecule^-1?s^-1, and thus the atmospheric lifetime of MHP is estimated at 2.9 days. Furthermore, from detailed analysis of the UV photolysis of MHP, the yield of OH radicals is obtained to be 0.91±0.04. Based on the MHP atmospheric lifetime and the yield of OH radicals, it is concluded that MHP plays an essential role in the redistribution of OH radicals in the troposphere.     

The formation and thermal decomposition of 4-hydroperoxy-2-hydroxy-3,4,6-triisopropylcyclohexa-2,5-dienone

Auto-oxidation of 3,4,6-triisopropylcatechol affords crystalline 2-hydroxy-4-hydroperoxy-3,4,6-triisopropylcyclohexa-2,5-dienone. Thermal decomposition of the resulting hydroperoxide was carried out and the reaction products were determined. The decomposition mainly proceeds by a route without cleavage of the O—O bond, unusual for hydroperoxides, to give the starting 3,4,6-triisopropylcatechol and 3,4,6-triisopropylbenzo-1,2-quinone. The hydroperoxide decomposes in part according to the traditional pattern involving the O—O bond cleavage to give 3-hydroxy-2,5-diisopropylbenzo-1,4-quinone.     

水辅助下的OH自由基与CH_3OOH气相反应机理的理论研究

利用量子化学计算方法对单个水分子不存在与存在的情况下OH自由基与CH3OOH的气相氢抽取反应进行了理论研究.在BHand HLYP/6-311++G(2df,2pd)理论水平下优化了所有驻点的几何构型,在此基础上利用CCSD(T)/cc-p VTZ方法对所有驻点的单点能重新进行了计算.计算结果表明,OH自由基与CH3OOH反应的主要通道是OH自由基抽取CH3OOH中的-OH基团上的H原子.在单个水分子存在的情况下,反应的主要通道没有改变,但是水化过渡态的能量显著地降低,显然单个水分子对OH+CH3OOH反应具有催化效应.     

Features of α-phenylisopropyl hydroperoxide decomposition catalyzed by cetyltrimethylammonium bromide

The features of cumene oxidation, α-phenylisopropyl hydroperoxide (ROOH) decomposition, and free radical formation in the presence of cetyltrimethylammonium bromide (CTAB) were studied by the kinetic methods and TLC product analysis. It was found that CTAB catalyzes ROOH decomposition to free radicals. The efficiency of an initiating system CTAB—ROOH is by a factor of 2.5 higher than that of a combination CTAB with α-phenylethyl hydroperoxide. In addition, CTAB catalyzes the reactions of ROOH with α-tocopherol and 2,2′-bis[2-(p-dimethylaminophenyl)indane-1,3-dione]. The kinetic characteristics of these reactions were determined. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1802–1807, August, 2005.     

Syntheses of antimony(v) derivatives from trimethyl and triphenylantimony(III), dihydric phenols,andtert-butyl hydroperoxide

Trimethyl and triphenylantimonyo-phenylene dioxides were obtained by the reaction of trimethyl- and triphenylantimony with pyrocatechol in the presence oftert-butyl hydroperoxide in 68 and 81 % yields, respectively. 7,7,7,15,15,15-Hexamethyl-(and phenyl)-6,8,14,16-tetraoxa-7, 15-distibatricyclo[11.3.1.1^9,13]octadeca-1,3,5,9,11,13-hexaenes were synthesized analogously by the reaction with resorcinol (in 79 and 93 % yields, respectively). The use of hydroquinone resulted in polymeric trimethyl- and triphenylantimony hydroquinolates.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 748–751, April, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No 94-03-08846).     

Regioselective radical cyclization initiated by the reaction of allylic hydroperoxides with iron(II) sulfate

Treatment of 1-methyl-2-methylene-1-cyclohexyl hydroperoxide with a mixture of FeSO₄/CuCl₂ yielded 1-(1-chlorocyclohexyl)ethanone as the major product consistent with 6-endo-trig cyclization of the intermediate 5-acetylhex-5-enyl radical. This strategy was extended to the ring enlargement of a series of 1-isopropenylcycloalkyl hydroperoxides. Regioselective 7- or 8-endo-trig cyclization reactions could be achieved by treatment of the corresponding cyclopentyl or cyclohexyl hydroperoxides with either a mixture of FeSO₄/CuCl₂ or with FeSO₄ only. The influence of substituents on the efficiency of the 8-endo-trig cyclization process was also explored.     

Photogenerated hydroperoxides of EPDM rubbers and their characterization

Three different ethylene/propylene/diene (EPDM) rubbers were allowed to react with singlet oxygen. This reaction leads to the production of polymeric pendant hydroperoxides only in one case. Terpolymer ethylene/propylene/5-ethylidene-2-norbornene reacts with singlet oxygen and isolated and associated secondary hydroperoxides are formed. Anthracene was used as a sensitizer for production of singlet oxygen under 365-nm irradiation. The course of hydroperoxide formation was similar in the solid state as well as in the toluene solution. Reactivity of hydroperoxides prepared was tested in their reaction with gaseous dimethyl sulfide (DMS). Both the isolated and associated hydroperoxides react with DMS by dual fast and slow process. Fast process is more significant in the case of the isolated hydroperoxides. © 1995 John Wiley & Sons, Inc.     

Coupled hydroperoxide lyase and alcohol dehydrogenase for selective synthesis of aldehyde or alcohol

The main objective of this work was to improve the selective synthesis of a volatile compound: aldehyde or alcohol using a coupled-enzyme system. A novel method of synthesis of C₆-aldehyde or alcohol was carried out in the presence of hydroperoxide lyase (HPLS) activity coupled to alcohol dehydrogenase (ADH) activity. After cleavage of the initial substrate, hydroperoxy fatty acid catalyzed by HPLS, the second enzyme, ADH, can catalyze the reduction of the aldehyde to the corresponding alcohol, or the oxidation of contaminating alcohol into aldehyde, depending on the cofactor present in the medium (oxidized or reduced form). We succeeded in improving the synthesis of one of the products. When coupling HPLS to NADP, the selectivity of hexanal production from 13-hydroperoxy linoleic acid was improved, and hexanol production was reduced 5 to 10 times after 15 min of reaction at 15 °C and pH 7.0. In another experiment, HPLS was coupled to ADH in the presence of NADH. The production of alcohol (hexenols) was then favored especially when using 13-hydroperoxy linolenic acid as substrate at concentrations >15 mM, reaching 95% of the products. Coupling of the enzymatic reactions (cleavage reduction) not only reduced the number of steps but also allowed us to increase the conversion rate of the initial substrate (hydroperoxy fatty acid). Structures of the compounds produced in this work were confirmed using gas chromatography-mass spectroscopy analysis. Each of these products has its own delicately different fresh odor that can be used in various applications.