Butyl peroxide, decomposition

The experimental activation energies given in the last column of Table II are in the anticipated order of magnitudes. The activation energy of 24.0 kcal. per mole for the oxidation of 1-hexadecene to hydroperoxide is close to the value of 25.3 kcal. per mole recently reported for the constant velocity of peroxide accumulation. .. for butene-1 (9). The activation energy for the alkenyl hydroperoxide decomposition is reasonable. The activation energy of 48.1 kcal. per mole for the decomposition polymeric dialkyl peroxide is considerably higher than the value of about 37 kcal. per mole for tert-butyl peroxide decomposition. The... 

This retardation of ethyl tert-butyl peroxide decomposition may possibly be caused by competition between the inhibitor and the peroxide for methyl radicals (Reactions 1-4). 

Let us now trace stoichiometry of auto-induced di-tert-butyl peroxide decomposition Me3COOCMe3 -a 2Me3CO ... 

Thus the primary reaction in di-fe/f-butyl peroxide decomposition is a usual decomposition reaction in the scheme (1.10) the secondary reaction induced by the initial one is described by the scheme (1.11). It is worthy of note that both decomposition reactions are described by the same overall equation, and free radical is the general intermediate particle. 

Use the integral method to confirm that the reaction order for the di-fert-butyl peroxide decomposition described in Example S-1 is first order. 

The use of the differential method of data analysis to determine reaction orders and specific reaction rates is clearly one of the easiest, since it requires only one experiment. However, other effects, such as the presence of a significant reverse reaction, could render the differential method ineffective. In these cases, the method of initial rates could be used to determine the reaction order and the specific rate constant. Here, a series of experiments is carried out at different initial concentrations, C q, and the initial rate of reaction, is determined for each run. The initial rate, can be found by differentiating the data and extrapolating to zero time. For example, in the tfi-tert-butyl peroxide decomposition shown in Example 5-1, the initial rate was found to be... 

Postulate a reasonable mechanism for the di-t-butyl peroxide decomposition. Indicate how all the above facts are consistent with the proposed mechanism. 

Because di-/ fZ-alkyl peroxides are less susceptible to radical-induced decompositions, they are safer and more efficient radical generators than primary or secondary dialkyl peroxides. They are the preferred dialkyl peroxides for generating free radicals for commercial appHcations. Without reactive substrates present, di-/ fZ-alkyl peroxides decompose to generate alcohols, ketones, hydrocarbons, and minor amounts of ethers, epoxides, and carbon monoxide. Photolysis of di-/ fZ-butyl peroxide generates / fZ-butoxy radicals at low temperatures (75), whereas thermolysis at high temperatures generates methyl radicals by P-scission (44). 

The radical is generated by photolytic decomposition of di-/-butyl peroxide in methylcy-clopropane, a process that leads to selective abstraction of a methyl hydrogen from methylcyclopropane ... 

The decomposition of di- e -butyl peroxide in the presence of diethyl phosphite and an aromatic substrate leads to free-radical phosphination, Eqs. (43) and (44). 

The chemistry of the di-/-butyl and cumyl peroxides is relatively uncomplicated by induced or ionic decomposition mechanisms. However, induced decomposition of di-/-butyl peroxide has been observed in primary or secondary alcohols31" "14 (Scheme 3.37) and primary or secondary amines.312 The reaction... 

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. 

A singlet pair of <-butyl radicals produced by peroxide decomposition disproportionate to yield isobutane and isobutene [equation (41)]. Both products show E/A multiplet effects. 

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... 

Di-f-butyl peroxide is a commonly used free-radical initiator that decomposes according to first-order kinetics. Use the following data to estimate AVact for the decomposition in toluene at 120°C ... 

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. 

Preparing tert-butyl peroxide by the effect of 50% hydrogen peroxide in the presence of 78% sulphuric acid has led to numerous accidents. They were due to the high exothermicity of the reaction causing a temperature rise and leading to the explosive decomposition of the peroxide formed, if the temperature rise is badly monitored. 

Decomposition of Peroxides by Various Stabilizers. The efficiency of tert-butyl hydroperoxide decomposition in tert-butyl alcohol by various additives was determined (Table 9). Under the conditions of these experiments, the phenolic antioxidants and dilauryl thiodipropionate had little or, often, no effect on the hydroperoxide decomposition. The three zinc salts effectively inhibited peroxide decomposition. This effect might briefly inhibit the onset of substrate oxidation under weathering-test conditions, but the peroxide would decompose whenever its concentration reached a sufficient level to permit significant light... 

Ethylene-propylene and silicone rubbers are crosslinked by compounding with a peroxide such as dicumyl peroxide or di-t-butyl peroxide and then heating the mixture. Peroxide cross-linking involves the formation of polymer radicals via hydrogen abstraction by the peroxy radicals formed from the decomposition of the peroxide. Crosslinks are formed by coupling of the polymer radicals... 

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. 

The data of the table are of the decomposition of di-t-butyl peroxide to acetone and ethane at 188 C in a tubular flow reactor of 82.4 cc volume. The concentrations are in mol/liter and flow rate is in cc/sec. A carrier gas was used, and any volume change resulting from the reaction may be taken negligible. Find the rate equation. 

The decomposition of gaseous di-t-butyl peroxide in the presence of a nitrogen carrier gas (D) has been studied near 481 K in a CSTR (Mulcahy Williams, Austral J Chem 14 534, 1961). 

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. 

The reaction of EtsSiH with [l.l.l]propellane under photolytical decomposition of di-tert-butyl peroxide afforded products 17 and 18 in 1 3 ratio (Reaction 5.15) [36]. A rate constant of 6.0 x 10 M s at 19 °C for the addition EtsSi radical to [l.l.l]propellane was determined by laser flash photolysis [37]. Thus, it would appear that [l.l.l]propellane is slightly more reactive toward attack by EtsSi radicals than is styrene, and significantly more reactive than 1-hexene (cf. Table 5.1). 

The various initiators are used at different temperatures depending on their rates of decomposition. Thus azobisisobutyronitrile (AIBN) is commonly used at 50-70°C, acetyl peroxide at 70-90°C, benzoyl peroxide at 80-95°C, and dicumyl or di-t-butyl peroxide at 120-140°C. The value of the decomposition rate constant kj varies in the range... 

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