Thermal butyl peroxide

In the case of allyl peroxides (12 X= CH2, A=CH2, BO),1 1 1 intramolecular homolytic substitution on the 0-0 bond gives an epoxy end group as shown in Scheme 6.18 (1,3-Sn/ mechanism). The peroxides 52-59 are thermally stable under the conditions used to determine their chain transfer activity (Table 6.10). The transfer constants are more than two orders of magnitude higher than those for dialkyi peroxides such as di-f-butyl peroxide (Q=0.00023-0.0013) or di-isopropyl peroxide (C =0.0003) which are believed to give chain transfer by direct attack on the 0-0 bond.49 This is circumstantial evidence in favor of the addition-fragmentation mechanism. 

The determination of A V is illustrated by data for the thermal decomposition of di-ferf-butyl peroxide.10 The rate constants at 120 °C in toluene are as follows ... 

A plot of the logarithm of the rate constant for the thermal decomposition of di-rm-butyl peroxide with pressure. The data, from Ref. 10, refer to a temperature of 120 °C in toluene. 

The addition of (TMS)3SiH to a number of monosubstituted acetylenes has also been studied in some detail. These reactions are highly regioselective (anti-Markovnikov) and give terminal (TMSlsSi-substituted alkenes in good yields. High cis or trans stereoselectivity is also observed, depending on the nature of the substituents at the acetylenic moiety. For example, the reaction of the alkynes 23 and 24 with (TMSlsSiH, initiated either by EtsB at room temperature (method or by thermal decomposition of di-ferf-butyl peroxide at 160 °C... 

In order to bring about crosslinking of polyesters with styrene one of two types of initiator systems is used, which differ in the temperature at which they are effective. For curing at elevated temperatures, peroxides are used which decompose thermally to yield free radicals. Among those peroxides employed are benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxide, and dodecyl peroxide. Mixtures of polyester prepolymer, styrene, and such initiators are reasonably stable at room temperatures but undergo fairly rapid crosslinking at temperatures between 70 °C and 150 °C, depending on which particular peroxide is used. 

Pyrolysis of the phosphorodichloridothioate (59) at 550 °C gives mainly dibenzothiophen and a smaller amount of the cyclic phosphonochlorido-thioate (60). Thermal decomposition of di-t-butyl peroxide in triethyl phosphate gives rise to diethyl methyl phosphate in a reaction which may be interpreted as resulting from attack of methyl radical on the phosphoryl oxygen. An extension of this mechanism accounts for the formation of (61) from tri-isopropyl phosphate under the same conditions. 

At pressures above 6000 bar, free radical polymerisation sometimes proceeded explosively [ 1 ]. The parameters were determined in a batch reactor for thermal runaway polymerisation of acrylonitrile initiated by azoisobutyronitrile, dibenzoyl peroxide or di-/er/-butyl peroxide [2],... 

Biesenberg, J. S. etal., J. Polym. Eng. Sci., 1976,16, 101-116 Polymerisation of methyl methacrylate initiated by oxygen or peroxides proceeds with a steady increase in velocity during a variable induction period, at the end of which a violent 90°C exotherm occurs. This was attributed to an increase in chain branching, and not to a decrease in heat transfer arising from the increasing viscosity [ 1 ]. The parameters were determined in a batch reactor for thermal runaway polymerisation of methyl methacrylate, initiated by azoisobutyronitrile, dibenzoyl peroxide or di-ferf-butyl peroxide [2],... 

Some examples, such as thermal polymerization of styrene and decomposition of di-f-butyl peroxide, are given in [194], both treated as first-order reactions. The activation energy found for the decomposition of di-f-butyl peroxide agrees well with the literature value. From the pressure data, it appears that the initial pressure rise is caused by the evaporation of toluene, present as a solvent. At higher temperatures, the gases generated by decomposition are the main contributors to the pressure rise. 

A number of reports on the thermal decomposition of peroxides have been published. The thermal decompositions of f-butyl peroxyacetate and f-butyl peroxypivalate, of HCOH and a kinetic study of the acid-induced decomposition of di-f-butyl peroxide in n-heptane at high temperatures and pressures have been reported. Thermolysis of substituted f-butyl (2-phenylprop-2-yl) peroxides gave acetophenone as the major product, formed via fragmentation of intermediate alkoxy radicals RCH2C(Ph)(Me)0. A study of the thermolysis mechanism of di-f-butyl and di-f-amyl peroxide by ESR and spin-trapping techniques has been reported. The di-f-amyloxy radical has been trapped for the first time. jS-Scission reaction is much faster in di-f-amyloxyl radicals than in r-butoxyl radicals. The radicals derived from di-f-butyl peroxide are more reactive towards hydrogen abstraction from toluene than those derived from di-f-amyl peroxide. 

Fig. 21. Inverse recombination probability of f-butyl radicals formed from O, di-f-butyl peroxide (DBP) by photo-dissociation , di-f-butyl hyponitrite (DBH) by thermal dissociation and A, di-f-butyl peroxyoxalate (DBPO) by thermal dissociation plotted against the inverse viscosity of the solvent. The temperature was 45°C. After Kiefer and Traylor [288 ].

The first estimates were made by Volman and co-workers. Brinton and Volman (7) studied the thermal decomposition of di-tert-butyl peroxide between 129° and 154°C. in the presence of ethyleneimine. 

Birss, Danby, and Hinshelwood (6) investigated the thermal decomposition of di-fert-butyl peroxide from 130° to 170°C. in the presence of NO. In that investigation, Reaction 24a was in competition with... 

Mulcahy and Williams (32) looked at the thermal decomposition of di-fer -butyl peroxide at 482°, 516°, and 547°K. in the presence of C6H5OH. Reaction 24a was definitely in the second-order region. At... 

Hoare and Wellington (22) produced CH3O radicals from the photochemical (50° and 100°C.) and thermal (135°C.) decompositions of di-terf-butyl peroxide in the presence of 02. The initially formed tert-butoxy radicals decomposed to acetone plus methyl radicals, and the methyl radicals oxidized to methoxy radicals. Formaldehyde and CH3OH were products of the reaction the formation of the former was inhibited, and the latter was enhanced as the reaction proceeded. If the sole fate of CH3O were either... 

A recent oommtiruo tion by Gritter and Wallace discloses initiation of a study of the free-radical chemistry of epoxides Under the influence of U t-butoxy radicals, formed by thermal decomposition of di-lerf-butyl peroxide, propylene oxide is believed to yield an epoxy radical as shown in Eq. (3). The latter undergoes Isomerization to CHsCOCH - and further reaction with unreaoted propylene oxide or other available substrates, such as 1-octene, toluene, oyolohexene, and ethanol,fl7a as shown in Eq. (3). 

The parameters were determined in a batch reactor for thermal runaway polymerisation of styrene, initiated by azoisibutyronitrile, dibenzoyl peroxide or di-ferf-butyl peroxide. 

Epoxynovolak resin and BPA/DC-BMI prepolymer, tert.butyl peroxide and Zn acetate [106, 107] or 2-phenylimidazole and other catalysts [108] were filled with wollastonite. Carbon-fiber reinforced composites were obtained using a binder, which consisted of BPA/DC, BMI, an epoxynovolak, 2-ethyl-4-methylimidazole and an organic solvent [109]. A BPA/DC-BMI prepolymer in methylethylketone was mixed with middle-molecular-weight epoxide resin (Epikote 1001), 2-ethyl-4-methyl-imidazole, Zn acetate and triethylenediamine thermal shock resistant GRP was thus obtained [110]. 

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