Butyl peroxide, rate

Acyl radicals can fragment with toss of carbon monoxide. Decarbonylation is slower than decarboxylation, but the rate also depends on the stability of the radical that is formed. For example, when reaction of isobutyraldehyde with carbon tetrachloride is initiated by t-butyl peroxide, both isopropyl chloride and isobutyroyl chloride are formed. Decarbonylation is competitive with the chlorine-atom abstraction. 

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 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 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... 

Consider the polymerization of styrene initiated by di-t-butyl peroxide at 60°C. For a solution of 0.01 M peroxide and 1.0 M styrene in benzene, the initial rates of initiation and polymerization are 4.0 x 10 11 and 1.5 x 10 7 mol L 1 s 1, respectively. Calculate the values of (jkj), the initial kinetic chain length, and the initial degree of polymerization. Indicate how often on the average chain transfer occurs per each initiating radical from the peroxide. What is the breadth of the molecular weight distribution that is expected, that is, what is the value of Xw/Xnl Use the following chain-transfer constants ... 

Oxidation of 1,4-thioxane by BTSP and f-butyl(trimethylsilyl) peroxide in CHCI3 at 25 °C is compared to those of the same substrate by the more common oxidants, f-butyl hydroperoxide and di-f-butyl peroxide, in the same solvent. The two silyl peroxides give similar oxidations rates, which are over 50 times higher than that measured for f-BuOOH, while f-Bu202 is almost unreactive under the conditions adopted. Oxidation... 

Let us assume that fci is equal to k9, the rate constant for the gas phase decomposition (15), where no cage effect is expected. This assumption does not always hold (15, 18). For example, it is known (18) that di-f erf-butyl peroxide (DPB) decomposes about 30% slower in the gas phase than in solution. We can calculate from our value of k8 and the known value of kg, from the work of Szwarc (7, 21), a value for the fraction of acetoxy radical pairs recombining, fR, where... 

Aliphatic amines have much less effect on the later reactions of the gas-phase oxidation of acetaldehyde and ethyl ether than if added at the start of reaction. There is no evidence that they catalyze decomposition of peroxides, but they appear to retard decomposition of peracetic acid. Amines have no marked effect on the rate of decomposition of tert-butyl peroxide and ethyl tert-butyl peroxide. The nature of products formed from the peroxides is not altered by the amine, but product distribution is changed. Rate constants at 153°C. for the reaction between methyl radicals and amines are calculated for a number of primary, secondary, and tertiary amines and are compared with the effectiveness of the amine as an inhibitor of gas-phase oxidation reactions. 

Action of Aliphatic Amines on Decomposition of tert-Butyl Peroxide. The rate of decomposition of tert-butyl peroxide is not greatly affected... 

Action of Diethylamine on Decomposition of Ethyl tert-Butyl Peroxide. The rate of decomposition of ethyl ferf-butyl peroxide is decreased by adding diethylamine (Figure 7), and the yield of products is altered (Table II). Again, the yield of methane is increased at the expense of ethane and f erf-butyl alcohol is increased at the expense of acetone. Ethanol and acetaldehyde are formed in considerably greater amounts. The yields of carbon monoxide and methyl ethyl ketone are decreased. 

Even large amounts of aliphatic amines do not alter the rate of decomposition of tert-butyl peroxide, but they do slow down the rate of decomposition of ethyl tert-butyl peroxide. 

Methylation is taken as illustrative of alkylation for comparative purposes in Table 25 however, a wide range of other alkylations have been studied (76MI20503). Photolysis of di-r-butyl peroxide in a mixture of cyclohexane and pyridine gives cyclohexylation (equation 170) (7lCR(C)(272)854>. The relative rates for homolytic substitution of pyridines by cyclic alkyl radicals have been obtained (74JCS(P2)1699). A striking contrast can be seen (Table 26)... 

To examine the extent that cage and entropy had on the original data, activation parameters for the reduction of di-ferf-butyl peroxide were measured from a temperature study using a series of donors. These values are compared with those predicted by the model that accounts for cage and entropy effects and are summarized in Table 5. Examination of the two series of AG appears to account for the original discrepancy in the ET rate... 

Experiments without Solvents. At our rates of initiation, yields of hydroperoxide, tert-B iO>R/ (A02), in liquid-phase runs were about 75% at 50°, 90 to 93% at 100°C. tert-Butyl alcohol was a major product only at 50°C. with a high rate of initiation (Run 91) acetone was a minor product under all conditions. The termination product, 39% of the expected di-terf-butyl peroxide, was detected in Run 91 where ABN was used as the initiator. 

The half-life time, Tm, of decomposition of di(t-butyl)peroxide at a temperature of 463 K and ambient pressure is 50 s. One may calculate the rate constant and the half-life time for decomposition at 300 MPa and the same temperature, when the activation volume is Av = +13 cm3 mol"1. 

Thne-of-flight (TOF) mass spectrometric analysis of the pyrolysis fragments of di-t-butyl peroxide suggests t-BuCO as the primary product, followed by decomposition of this radical into CHj.253 Elsewhere, the kinetics of the pyrolysis of dimethyl, diethyl, and di-t-butyl peroxides in a modified adiabatic bomb calorimeter have been investigated.254 The lifetime of acyloxy radicals, generated by the photolysis or thermolysis of acetyl propionyl peroxide, have been studied. Chemical nuclear polarization has been used to determine the rate constant for the decarboxylation of these radical intermediates.255... 

Since the thermal decomposition of di-(-butyl peroxide occurs at convenient rates over the temperature range from 130 to 160°C. with relatively little chain character (Batt and Benson12), many workers have... 

Example The gas-phase thermal decomposition of one mole of di-tert-butyl peroxide, in a constant volume apparatus, yields two moles of acetone and one mole of ethane. If life reaction obeys first-order kinetics, develop expression the rate-constant as a function of time, initial pressure and total pressure. 

Independent Variables. Simultaneous synthesis of two polymer networks is a complex process. Many independent variables are available for study and not all could be explored in a limited investigation. The emphasis in the present study centers on those variables whose predominant effect is to influence the relative rates or gelation times of the reactions. Three independent variables were selected (a) the concentration of di-tert-butyl peroxide initiator was changed to vary the rate of polymerization of n-butyl acrylate (b) the epoxy mix was allowed to prereact for different lengths of time before the acrylate mix was added, and (c) the amount of DEGDM added to the acrylate mix was varied to control the gel time of the acrylate without significantly affecting its rate of polymerization. 

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