- Recombination of 1,1-dimethylpropyl peroxy radicals in polar solvents
-
The kinetics of 1,1-dimethylpropyl peroxy radicals recombination in polar solvents - water, methanol, and their mixtures - was studied by EPR spectroscopy in combination with the stopped-flow method, and the rate constants of this reaction were determined. Peroxyl radicals were generated by mixing solutions of Ce4+ sulfate and 1,1-dimethylpropyl hydroperoxide. The observed EPR signal of the peroxyl radical is a singlet with a g-factor of 2.015 ± 0.001, and a line width of ΔH = (1.36 ± 0.02) × 10-3 T for methanol and ΔH = (9.7 ± 0.2) × 10-4 T for water. The measured rate constants of (CH3)2C(O2 ·)CH2CH3 radical recombination at 298 K are 2k t = (3.9 ± 0.4) × 104 L mol-1 s-1 for water and 2k t = (5.2 ± 0.5) × 103 L mol-1 s-1 for methanol. A linear relationship between ln(2kt ) and the Kirkwood function (?-1)/(2? + 1), where e is the dielectric constant of the medium, has been established, indicating an important role of nonspecific solvation in the recombination of tertiary peroxyl radicals.
- Denisova,Shuvalov
-
-
Read Online
- Synthesis and purification method of high-purity tert-amyl peroxy-2-ethylhexyl carbonate
-
The invention belongs to the fields of peroxidation, organic synthesis and peroxide purification, and particularly relates to a synthesis and purification method of tert-amyl peroxy-2-ethylhexyl carbonate, which comprises the steps of peroxidation reaction, substitution synthesis reaction, peroxide purification and the like. According to the method, the discharge of the waste liquid and the treatment cost of subsequent waste liquid are reduced, the reaction conditions are easy to control, the product yield is high, the product purity is high, and the purity can reach 97% or above.
- -
-
Paragraph 0029-0031; 0034-0036; 0039-0041; 0044-0046
(2021/02/10)
-
- ONLINE CONTINUOUS FLOW PROCESS FOR THE SYNTHESIS OF ORGANIC PEROXIDES USING HYDROGEN PEROXIDE AS RAW MATERIAL
-
An online continuous flow production process for directly preparing organic peroxides by using hydrogen peroxide as a raw material. This production process uses hydrogen peroxide, catalyst, and an oxidation substrate as a raw material. Substrate will be turned to designated peroxides sequentially through oxidation and workup. This process is performed in a plug-and-produce integrated continuous flow reactor, and the raw materials are continuously fed to the reactor. So, specified peroxide can be continuously obtained at the outlet of the plug-and-produce integrated continuous flow reactor.
- -
-
Paragraph 0290; 0293
(2020/06/29)
-
- Organic hydroperoxide formation in the acid-catalyzed heterogeneous oxidation of aliphatic alcohols with hydrogen peroxide
-
Organic hydroperoxides (ROOH) are reactive species which play significant roles in atmospheric processes, such as acid precipitation, hydroxyl radical cycling and secondary organic aerosol formation. Despite their observation in the atmosphere, our understanding of their formation mechanism is still incomplete. In the present work, ROOH formation was found in the acid-catalyzed heterogeneous oxidation of aliphatic alcohols with hydrogen peroxide. The kinetics and mechanism of acid-catalyzed heterogeneous oxidation of three aliphatic alcohols (2-methyl-2-butanol, 3-buten-2-ol and 2-butanol) with hydrogen peroxide were investigated. Based on the experimental results, tertiary or allyl alcohols may contribute to ROOH formation through this route while secondary alcohols may not. The kinetic experiments were conducted in a rotated wetted-wall reactor coupled to a mass spectrometer at room temperature (298 K) with 40-70 wt% H2SO4 solution. The reactive uptake coefficients were acquired for the first time. The generation and degradation mechanisms of ROOH in acidic media were proposed according to the product information. Once formed, ROOH are found to undergo two degradation pathways: the acid-catalyzed rearrangement reaction and the organic hydrogen peroxysulfate formation pathway. The newly found acid-catalyzed process may occur under certain conditions and influence particle growth in the atmosphere.
- Liu, Qifan,Wang, Weigang,Liu, Ze,Wang, Tianhe,Wu, Lingyan,Ge, Maofa
-
p. 19716 - 19724
(2014/05/20)
-
- New route for conversion of camptothecin to 7-ethylcamptothecin and 7-propylcamptothecin
-
In this article, a new route for conversion of camptothecin to 7-ethylcamptothecin and 7-propylcamptothecin is described. Compared with previous reports, the reaction time of the new synthetic route was greatly shortened to 30 min, and the products were obtained in high yield. Copyright Taylor & Francis Group, LLC.
- Wang, Xin,Wu, Xiaojing,Cheng, Ning,Zhao, Huiqing,Gu, Zhihong,Shen, Xiang
-
p. 519 - 523
(2007/10/03)
-
- Process for the preparation of tertiary amyl hydroperoxide
-
The present invention provides an improved process for the production of tertiary amyl hydroperoxide by the liquid phase oxidation of isopentane in presence of air or molecular oxygen as oxidant using the oxides of Group IIA metals such as magnesium, calcium, strontium and barium in high pressure reactor under stirring conditions at a temperature ranging between 110°-180° C. and at moderate pressures for a period of 0.1-12 h. The catalyst reused for sevral times without affecting its catalytic performance. The present invention produces a tertiary amyl hydroperoxide with 40-60% selectivity and tertiary amyl alcohol, which has a numerius industrial applications.
- -
-
Page/Page column 4
(2008/06/13)
-
- AN IMPROVED PROCESS FOR THE PREPARATION OF TERTIARY AMYL HYDROPEROXIDE
-
The present invention provides an improved process for the production of tertiary amyl hydroperoxide by the liquid phase oxidation of isopentane in presence of air or molecular oxygen as oxidant using the oxides of Group IIA metals such as magnesium, calcium, strontium and barium in high pressure reactor under stirring conditions at a temperature ranging between 110°- 180oC and at moderate pressures for a period of 0.1- 12 h. The catalyst reused for several times without affecting its catalytic performance. The present invention produces a tertiary amyl hydroperoxide with 40-60 % selectivity and tertiary amyl alcohol, which has a numerius industrial applications.
- -
-
Page/Page column 9
(2008/06/13)
-
- Crystalline MWW-type titanosilicate catalyst for producing oxidized compound, production process for the catalyst, and process for producing oxidized compound by using the catalyst
-
A crystalline titanosilicate catalyst which is usable as a catalyst in the oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group, a process for producing the catalyst, and a process for producing an oxidized compound by an oxidation reaction using the catalyst. It has been found that a crystalline titanosilicate having a structural code of MWW effectively functions as a catalyst in an oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group, or a compound having a carbon-carbon double bond a functional group and having a total carbon number of not smaller than 2 and not larger than 5, wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent, thereby to highly selectively provide an intended oxidized compound.
- -
-
-
- Oxidations by the reagent "O2-H2O2-vanadium derivative-pyrazine-2-carboxylic acid". Part 12. Main features, kinetics and mechanism of alkane hydroperoxidation
-
Various combinations of vanadium derivatives (n-Bu4NVO3 is the best catalyst) with pyrazine-2-carboxylic acid (PCA) catalyse the oxidation of saturated hydrocarbons, RH, with hydrogen peroxide and air in acetonitrile solution to produce, at temperatures V(PCA)(H2O2) → VIV(PCA) + HOO. + H+. The VIV species thus formed reacts further with a second H2O2 molecule to generate the hydroxyl radical according to the equation VIV(PCA) + H2O2 → VV(PCA) + HO. + HO-. The concentration of the active species in the course of the catalytic process has been estimated to be as low as [V(PCA)H2O2] ≈ 3.3 × 10-6 mol dm-3. The effective rate constant for the cyclohexane oxidation (d[ROOH]/dt = keff[H2O2]0[V]0) is keff = 0.44 dm3 mol-1 s-1 at 40 °C, the effective activation energy is 17 ± 2 kcal mol-1. It is assumed that the accelerating role of PCA is due to its facilitating the proton transfer between the oxo and hydroxy ligands of the vanadium complex on the one hand and molecules of hydrogen peroxide and water on the other hand. For example: (pca)(O=)V ... H2O2 → (pca)(HO-)V-OOH. Such a "robot's arm mechanism" has analogies in enzyme catalysis.
- Shul'pin, Georgiy B.,Kozlov, Yuriy N.,Nizova, Galina V.,Suess-Fink, Georg,Stanislas, Sandrine,Kitaygorodskiy, Alex,Kulikova, Vera S.
-
p. 1351 - 1371
(2007/10/03)
-
- Molybdenum-catalyzed epoxidations of oct-1-ene and cyclohexene with organic hydroperoxides: Steric effects of the alkyl substituents of the hydroperoxide on the reaction rate
-
A kinetic study of the epoxidation of oct-1-ene and cyclohexene with alkyl hydroperoxides is reported. The alkyl hydroperoxides were obtained in a moderate to high purity from the corresponding alcohols by acid-catalyzed exchange with hydrogen peroxide. The reaction rates in pseudo first-order experiments of these olefins with various alkyl hydroperoxides strongly depend on the structure of the alkyl group of the alkyl hydroperoxide. When one of the methyl groups in tert-butyl hydroperoxide (TBHP, 4a) is substituted by an alkyl group, R, the reaction rate decreases in the order Et > Pr > Bu > t BuCH2 > tBu. Substitution of two methyl groups of TBHP as in 1-ethyl-1-methylpropyl hydroperoxide (5a) and 1-ethyl-1-methylbutyl hydroperoxide (5b) showed a further decrease in reaction rate of epoxidation. When all three methyl groups are substituted by, for example, three ethyl groups as in 1,1-diethylpropyl hydroperoxide (6a) a decrease of approximately 99% in reaction rate is observed. Introduction of a ring system in the hydroperoxide such as in cyclohexyl hydroperoxide (3), 1-methyl-cyclohexyl hydroperoxide (2) and pinane hydroperoxide (1) also showed a dramatic decrease in reaction rate of epoxidation. An investigation of relative rates of epoxidation in competition experiments of cyclohexene and hex-1-ene with 1-tert-butylcyclohexene with different alkyl hydroperoxides also showed them to depend on the structure of the alkyl group of the alkyl hydroperoxide. These results are rationalized on the basis of a mechanism involving nucleophilic attack of the olefin on an alkylperoxomolybdenum(VI) intermediate. Bulky substituents at the α-position in the alkyl hydroperoxide can seriously impede the approach of the olefin to the O-O bond.
- Lempers,Van Crey,Sheldon
-
p. 542 - 546
(2007/10/03)
-
- Novel organic peroxides and their use in the preparation of epoxide groups containing (co)polymers
-
Novel organic peroxides of the general formula wherein p = 0 or 1 and n = 1, 2, 3 or 4 are described. These peroxides are excellently suitable for use in the preparation of epoxide groups-containing (co)polymers. Also described are shaped objects obtained by using (co)polymers thus modified.
- -
-
-
- Homolytic Decomposition of t-Alkyl 2,2-Dimethylperoxypropionates
-
Decomposition rates and products of t-alkyl 2,2-dimethylperoxypropionates were measured in cumene at several temperatures.The peroxyesters decomposed homolitycally, depending on the structure of the t-alkyl moiety.The relative rates of the t-alkyl moieties to the 1,1-dimethylethyl one were: 1,1-dimethylbutyl (1.14), 1,1-dimethylpropyl (1.19), 1,1,2-trimethylpropyl (1.85), 1,1,3,3-tetramethylbutyl (2.10), and 1,1-dimethyl-2-phenylethyl (2.34).The decomposition showed an isokinetic relationship and the importance of stabilization by hyperconjugation.Based on these data, the decomposition mechanism, which contains a slight stretching of the Cα-Cβ bond to the peroxyl oxygen at the transition state is, discussed.
- Komai, Takeshi,Matsuyama, Kazuo,Matsushima, Masaru
-
p. 1641 - 1646
(2007/10/02)
-
