Substituent Effects of Alkyl Groups on the Decomposition of tert-Alkyl Peroxides
摘要:
In order to clarify substituent effects of alkyl groups on the decomposition of various tert-alkyl peroxides (RCMe(2)OOR'), the decomposition of 1-methoxy-1-(tert-alkylperoxy)cyclohexanes 3 and 1,1-bis(tert-alkylperoxy)cyclohexanes 4 has been studied by use of methods of kinetics and product analysis in cumene with the range of temperatures from 80-110 degrees C and compared with those of the corresponding peroxyesters (1; R' = CO-t-Bu) and dialkyl peroxides (2; R' = t-Bu). The decomposition rates for each peroxide series decrease in the following order: 1 much greater than 3 much greater than 4 much greater than 2. The decomposition rate for the series of peroxides 1 decreases in the following order: R = t-BuCH(2) much greater than i-Pr much greater than Et > Pr > Me. But, for the series of peroxides 2, 3, and 4, R = t-BuCH(2) much greater than i-Pr much greater than Pr > Et much greater than Me. The decomposition rate is expressed by a modified Taft equation: log k(d) = rho*Sigma sigma(CH2R)* + nh + C, which contains both inductive and C-H hyperoconjugation effects of alkyl groups. On the basis of the isokinetic relationship of the activation parameters, the Taft equation, and the decomposition products, the decomposion mechanism via an polar activation complex having a slightly stretched C-alpha - C-beta bond neighboring to the peroxy oxygen atom is suggested and the abnormal behavior of neopentyl group is discussed.
Substituent Effects of Alkyl Groups on the Decomposition of tert-Alkyl Peroxides
摘要:
In order to clarify substituent effects of alkyl groups on the decomposition of various tert-alkyl peroxides (RCMe(2)OOR'), the decomposition of 1-methoxy-1-(tert-alkylperoxy)cyclohexanes 3 and 1,1-bis(tert-alkylperoxy)cyclohexanes 4 has been studied by use of methods of kinetics and product analysis in cumene with the range of temperatures from 80-110 degrees C and compared with those of the corresponding peroxyesters (1; R' = CO-t-Bu) and dialkyl peroxides (2; R' = t-Bu). The decomposition rates for each peroxide series decrease in the following order: 1 much greater than 3 much greater than 4 much greater than 2. The decomposition rate for the series of peroxides 1 decreases in the following order: R = t-BuCH(2) much greater than i-Pr much greater than Et > Pr > Me. But, for the series of peroxides 2, 3, and 4, R = t-BuCH(2) much greater than i-Pr much greater than Pr > Et much greater than Me. The decomposition rate is expressed by a modified Taft equation: log k(d) = rho*Sigma sigma(CH2R)* + nh + C, which contains both inductive and C-H hyperoconjugation effects of alkyl groups. On the basis of the isokinetic relationship of the activation parameters, the Taft equation, and the decomposition products, the decomposion mechanism via an polar activation complex having a slightly stretched C-alpha - C-beta bond neighboring to the peroxy oxygen atom is suggested and the abnormal behavior of neopentyl group is discussed.
Enhanced conversion rates are realized in a suspension polymerization process for styrene through the use of peroxide initiators having one hour half life temperatures from 101° to 111° C are disclosed. Also disclosed are suitable initiator combinations which provide polymeric products with low residual monomer content at reduced process temperatures, polymerizable compositions containing such initiators and products produced by such processes and compositions.
Process for the preparation of expandable polystyrene
申请人:ARKEMA FRANCE
公开号:EP2105457A1
公开(公告)日:2009-09-30
The present invention relates to a process for the preparation of expandable polystyrene comprising the following steps :
- i°) heating an aqueous suspension comprising styrene monomer and at least one organic peroxide initiator of formula (I) 1-alkoxy-1-t-alkylperoxycyclohexane in which the alkoxy group contains 1 to 4 carbon atoms, the t-alkyl group contains 4 to 12 carbon atoms, and the cyclohexane ring may optionally be substituted with 1 to 3 alkyl groups each, independently having 1 to 3 carbon atoms, at a temperature ranging from 100°C to 120°C,
- ii°) adding a blowing agent selected from the group consisting of alkanes having from 4 to 6 carbon atoms and mixtures thereof.
The invention also relates to an expandable polystyrene obtainable according to such a process and to insulation parts and packaging comprising such an expandable polystyrene.
Promoters for peroxides in aqueous treatment fluids
申请人:Arkema Inc.
公开号:US10138413B2
公开(公告)日:2018-11-27
The addition of at least one promoter selected from the group consisting of thiosulfate salts, sulfite salts, bisulfite salts, erythorbate salts, isoascorbate salts, and combinations thereof to an aqueous treatment fluid containing a viscosifying polymer and a peroxide helps to promote the activity of the peroxide as a breaker, thus facilitating a reduction in viscosity of the aqueous treatment fluid at lower temperatures than are possible in the absence of the promoter. The promoted aqueous treatment fluid is useful as a fracture fluid to fracture subterranean formations in oil and gas recovery.
Compositions and methods for breaking hydraulic fracturing fluids
申请人:Arkema Inc.
公开号:US10294414B2
公开(公告)日:2019-05-21
A breaker composition for use in a fracturing fluid comprises water, at least one peroxide (e.g., tert-butyl hydroperoxide), and optionally at least one alcohol (e.g., propylene glycol and/or a butyl alcohol). The peroxide(s) and optional alcohol(s) are present in amounts effective to reduce the viscosity of a fracturing fluid at a temperature of 90-300 F. (the “breaking temperature”), and to prevent rehealing of the fracturing fluid, i.e., to maintain the reduced viscosity for a period of time after the temperature is reduced from the breaking temperature to a temperature below the breaking temperature (e.g., after the temperature is reduced from the breaking temperature to room temperature).
Stable organic peroxide compositions include at least one organic peroxide (e.g., tert-butyl hydroperoxide), at least one dye (e.g., an FD&C dye), and at least one alcohol (e.g., propylene glycol, tert-butanol, and/or glycerin).