Acyl peroxides benzoyl peroxide

There are solid phase enthalpy of formation data for four aromatic acyl peroxides dibenzoyl peroxide and the bis-o- and bis-p-toluyl derivatives and dicinnamoyl peroxide. The last three were reported in the same publication . The first disconcerting observation is that the p-methyl substituted benzoyl peroxide is less stable than the ortho isomer by nearly 50 kJmol. We cannot reconcile the large difference between the enthalpies of formation of these two isomers, especially since the corresponding anhydrides have comparable enthalpies of formation, —521.0 + 7.9 (p ) and —533.5 + 7.9 (o )kJmol . However, they too exhibit an unexpected stability order and were measured by the same... 

Organic peroxides acyl peroxides (benzoyl, acetyl, lauryl peroxides, etc), alkyl peroxides, hydroperoxides, etc. are used as polymerization initiators. Azocompounds (for example, redox systems, etc. are also widely used as initiators. In... 

The experimental data on the reactions of ketyl radicals with hydrogen and benzoyl peroxides were analyzed within the framework of IPM [68]. The elementary step was treated as a reaction with the dissociation of the O—H bond of the ketyl radical and formation of the same bond in acid (from acyl peroxide), alcohol (from alkyl peroxide), and water (from hydrogen peroxide). The hydroperoxyl radical also possesses the reducing activity and reacts with hydrogen peroxide by the reaction... 

Benzoyl chloride is used in the manufacture of benzoyl peroxide and dye intermediates, for acylation (introduction of the benzoyl group into alcohols, phenols and amines), and as an analytical reagent (Lewis, 1993 Budavari, 1996). 

In titanium acylates, the carboxylate ligands are unidentate, not bidentate, as shown by ir studies (333,334). The ligands are generally prepared from the halide and silver acylate (335). The benzoate is available also from a curious oxidative addition with benzoyl peroxide (335—338) ... 

Subsequent loss of carbon dioxide from the alkyl acyl carbonate may occur. It was estimated, in the decomposition of Ira 5-4-I-butylcyclohexanecarbonyl peroxide in carbon tetrachloride, that two-thirds of the reaction occurs via the inversion process and one-third by the homolytic process It is suspected that inversion may be major decomposition route for other secondary aliphatic diacyl peroxides as well as for some bridgehead peroxides . Confirmation that the inversion process does contribute to the decomposition of i-butyryl peroxide is given . Further evidence for the inversion process is found in the volumes of activation for the decomposition of i-butyryl peroxide in isooctane at 50° and ram-4-r-butylcyclohexanecarbonyl peroxide in -butane at 40 °C. The AF values are —5.1 and —4.1 cm. mole , respectively. These values may be compared to the positive values of A F for benzoyl peroxide (Table 77) where there is no inversion. While the transition states for homolytic decomposition and inversion for secondary and tertiary diacyl peroxides are both polar, it is felt that the transition state for inversion is more polar . The extent of contribution of structure (V) to the transition state in the homolytic decomposition must be held with considerable reservation. In general much of the reported data for the decomposition of secondary and tertiary alkyl diacyl peroxides should be viewed with some scepticism unless efforts were made to assess the importance of the inversion process. One clue that may be used to evaluate the importance of this process is the yield of ester, which is a product of this reaction. 

O 53.89% expl oil or solid possessing the sharp ozone-like odor of volatile acyl peroxides, mp 28-35° (dec), decompg spontaneously at RT, deflgr on contact with a flame np 1.4017 at 20° sol in a wide range of org solvs si sol in w obtd in an impure form by Wieland et al (Ref 2) by reaction of ethyl chloroformate in chlf soln with powdered Na peroxide. Strain et al (Ref 3) prepd the compd by the same procedure but pointed out the special care that was reqd in temp control (0-10°) in all operations of prepn purification because of its high degree of thermal instability. When subjected to heat, friction or shock. Diethyl Peroxydicarbonate app>ears to be more sensitive than Benzoyl Peroxyde (qv)... 

In organic media amines can be used as the reductant [15,16] for redox initiation with acyl peroxides, an example being the combination of benzoyl peroxide and an N,N-dialkyl-aniline. 

Hydroxy sulfones can be easily transformed into derivatives for radical-mediated reactions such as thiobenzoates,220 xanthates,221,222 selenoben-zoates,221,222 and thionocarbonates.221,222 These substrates may be used in subsequent stereoselective syntheses of alkenes by free radical methods. Methyl xanthates usually give the best results in the olefination reaction, typically using O-acyl A - It y d roxy- 2 - thiopy ri d o n e under visible light irradiation. Alternatively, diphenylsilane in combination with radical initiators such as Et3B/02, benzoyl peroxide, or AIBN may also be used (Eq. 127).221 222... 

Among the initiators which have been used in the bulk polymerization of vinyl acetate are dibenzoyl peroxide (BPO) [48,71,72], benzoyl steroyl peroxide [71], disteroyl peroxide [71], dialiphatic acyl peroxides in general [71], 2,2 -azobisisobutyronitrile [37, 69, 72], pinacols [73], dilauroyl peroxide (LPO) [74], and difuroyl peroxide [74, 75]. 

Hardeners. The polymerisation reaction is initiated by peroxide radicals. Typical examples are cyclohexanone peroxide and methyl ethyl ketone peroxide (hydroperoxides), benzoyl peroxide, perbenzoates and peroctoates (acyl peroxides). It is standard to use around 4 % (calculated on the resin and styrene content) of a desensitised supply form (e.g. 50% peroxide in flexibiliser). The manufacturer s instructions are to be observed in handling peroxides. 

If the finish is to be stoved, a wide range of peroxides is suitable, depending on the temperature to be used and the pot-life required. Lauroyl, 2,4-dichlorobenzoyl and benzoyl peroxides (acyl peroxides) methyl ethyl ketone (MEK) peroxide and cyclohexanone peroxide (ketone peroxides) and cumene hydroperoxide are examples. 

Matsugo et al. (1998) reported that, three different water-soluble chitosan derivatives obtained by the acylation of chitosan inhibited thiobarbituric acid reactive substance formation in t-butylhy-droperoxide and benzoyl peroxide induced lipid peroxidations. 

Butanediamine (BDA)-g-PDLLA was synthesized by grafting maleic anhydride onto the side chains of PDLLA via melt-free radical polymerization using benzoyl peroxide as initiator. BDA was then grafted via a V-acylation reaction. The biodegradation behavior of these graft copolymers could... 

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