A kinetic study has been made of the decomposition of benzoyl peroxide in benzene. Kinetic data for this study have been obtained from three separate sets of measurements. Rate measurements from evolved carbon dioxide and direct iodometric measurements of peroxide are in good agreement. Alkali-metric determinations of the product, benzoic acid, have also been made during the course of the reaction.Gravimetric determinations show that the total evolved carbon dioxide from the reaction is a function of the temperature, and indicate that the mechanism involves two parallel fast reactions, one of which evolves one mole of carbon dioxide per mole of peroxide and the other two moles of carbon dioxide per mole of peroxide. The latter reaction predominates at higher temperatures.A kinetic analysis is included and provides for a slow reaction involving the rupture of the peroxide bond, followed by free radical reactions.[Formula: see text]The secondary free radical reactions would probably form hydrogen radicals, but there is evidence to support the view that these hydrogen radicals are not eliminated by mutual termination.The reaction is first order and the energy of activation was found to be 31,000 cal. per mole.
This paper presents the results of the measurement of the vapor pressure of vinyl acetate, over the temperature range from 0 °C. to the normal boiling point. The determinations were carried out on vacuum distilled samples with an isoteniscope, differing slightly in detail from that used by Smith and Menzies(7).The normal boiling point is 72.5 °C. The molecular heat of evaporation has been found to be 8211 calories. The equation which represents the results is[Formula: see text]Trouton's constant and the critical temperature have been found to be 23.8 and 228.3 °C.
Vol. 50 by using a thermometer graduated to 0.1°, which was compared with one recently calibrated by the Bureau of Standards. The filled pycnometer was weighed at each temperature and the density, given in Table I, was calculated from these weights. The coeEcient of cubical expansion of Pyrex glass used was that recently obtained by BuEngton and Latimer.3 All weights were reduced to vacuum.No recent determination of the density of bromoform has been made and those in the literature are not in close agreement. However, that of Perkin,4 2.9045 g./cc. at 15°, and the value selected for the International Critical Tables, 2.890 at 20°, agree well with our values.The following empirical equation for the variation of specific volume with temperature was obtained by the method of least squares from the data in Table I.Vi = 0.24204 [1 + 0.00090411 (/ -7.7) + 0.0000006766 (t -7.7)2](1)The values calculated by the aid of this equation differ by not more than three units in the last decimal place from the experimental points.
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