The kinetics of thermolysis of acetyl propinyl peroxide in acetone-d 6 in the temperature range 3233373 K was studied using NMR spectroscopy and the effect of chemically induced nuclear polarization. The peroxide decomposes in acetone at rates comparable with the rates of thermolysis in alcohols, yielding numerous products. In the examined temperature range, the solvent molecules act as efficient donors of deuterium atoms, forming acetylmethyl-d 5 radicals which recombine to a significant extent with the peroxide radicals. A scheme of the processes involved in decomposition of the peroxide was suggested. The parameters of the Arrhenius equation for the peroxide decomposition were determined.Diacyl peroxide are widely used as initiators of polymerization and other free-radical reactions in chemical and petrochemical industries. Therefore, it seems important to analyze the products of decomposition of diacyl peroxides in cheap and available solvents commercially produced in large amounts. One of such solvents is acetone. Data on decomposition of diacyl peroxides in acetone are scarce. Bagdasar'yan and Mulyutinskaya [1, 2] studied only the rate of thermolysis of a 0.185 solution of benzoyl peroxide at 348 K and determined the yields of benzoic acid and carbon dioxide. Leffler et al. studied the effect of methoxy and nitro substituents on the contributions of the radical and nonradical mechanisms in thermolysis of benzoyl peroxide [3] and determined the yield of certain products in decomposition of unstable bis(o-iodophenylacetyl) peroxide [4]. Dutka et al. [5] measured the rates of thermal decomposition of a series of diacyl peroxides and determined the contribution of the induced decomposition to the apparent constant of the process.For aliphatic diacyl peroxides, we found only a single paper [6] in which the product yields in decomposition of acetyl peroxide in a mixture of acetone with carbon tetrachloride were reported.Our goals were to study the effects of chemically induced nuclear polarization, perform kinetic measurements, and analyze, on the basis of the results obtained, the mechanism of thermolysis of one of the simplest unsymmetrical aliphatic diacyl peroxides, acetyl propionyl peroxide I, in acetone-d 6 . Figure 1 shows the 1 H NMR spectrum of a 0.5 M solution of I in the course of thermolysis. Positively polarized are the protons of ethene [d 5.39 ppm, s (4H)], methylene protons of 2-pentanone-d 5 CH 3 CH 2 . CD 2 COCD 3 [1.59 ppm, m (2H)], and methyl protons of butanone-d 5 CH 3 CD 2 COCD 3 [0.98 ppm, quintet (3H)] and propane [0.92 ppm, t (3H)]. Negatively polarized are the methylene protons of ethyl ethanoate [4.10 ppm, q (2H)] and propane [1.39 ppm, m (2H)] and methyl protons of 2-pentanone-d 5 [0.89 ppm, t (3H)] and methanes [0.19 ppm, s (CH 4 ); 0.17 ppm, t (CH 3 D)]. Also, protons of propane and 2-pentanoned 5 have an insignificant contribution of the multiplet 5 4 3 2 1 0 d, ppmFig. 1. 1 H NMR spectrum of a 0.5 M solution of peroxide I in acetone-d 6 at 368 K in the course of thermolysis.

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The reactions of methyl and ethyl esters of valine with m-bromobenzaldehyde and p-chlorobenzaldehyde in absolute methanol in the presence of magnesium sulfate yielded the corresponding azomethines (CH 3 ) 2 CHCH(COOR 1 )N=CHR 2 (R 1 = CH 3 , C 2 H 5 ; R 2 = 3-BrC 6 H 4 , 4-ClC 6 H 4 ); their reduction with sodium borohydride gave N-benzyl derivatives of valine esters, (CH 3 ) 2 CHCH(COOR 1 )NHCH 2 R 2 .

The photolysis of acetylpropionyl peroxide solutions in acetone at different temperatures has been investigated by the NMR method with consideration for the effects of chemical polarization of nuclei and the yields of the photolysis products. Acetylpropionyl peroxide decomposes when it is found in the binding or loosening triplet electron states. In the process of photolysis, acetone not only serves as the triplet sensitizer, but also effectively homologizes with the formation of methyl and acetyl radicals; however, it practically does not participate in the photoreduction.Introduction. Diacyl peroxides are useful products that in various electron states can generate free radicals. Analysis of the peroxide decomposition products, their yields, and the mechanism of their formation by the NMR method with consideration for the effects of chemical polarization of nuclei (CPN) allows one to obtain comprehensive data on the molecular and spin dynamics of the intermediates formed in a nanosecond time interval and the kinetics of the chemical reactions occurring in this case. Asymmetric diacyl peroxides are the most convenient for this analysis. One of the simplest asymmetric diacyl peroxides is acetylpropionyl peroxide (APP). Acetone is of particular interest as a solvent since, in addition to the high chemical activity and ready availability, it possesses an important propertythe ability to be a triplet sensitizer in photochemical reactions.There are a number of works [1][2][3][4][5] in which the thermolysis of aromatic diacyl peroxides in acetone was investigated, but we know of only one work devoted to an investigation of the thermolysis of acetyl peroxide in a mixture of acetone and carbon tetrachloride [6]. Data on the photolysis of such peroxides are absent.The aim of the present work is an investigation of the CPN effects, a pursuance of kinetic investigations, and an analysis, on their basis, of the mechanism of photolysis of acetylpropionyl peroxide in acetone-d 6 .Experimental Procedure. Acetylpropionyl peroxide was obtained by the method of [7]. The content of active oxygen, determined by the method of iodometric titration, was 99.5%.We investigated 0.1-M solutions of acetylpropionyl peroxide in acetone-d 6 (weight fraction of the basic substance 99.5%, degree of deuteration 99%). The qualitative and quantitative compositions of the products were determined by NMR spectroscopy of 1 H. The 1 H NMR spectra were recorded in the quantitative regime on BS-587A, BS-576A (Czechia), and AVANCE-400 (Germany) spectrometers with operating frequencies of 80, 100, and 400 MHz, respectively. For the purpose of investigating the CPN effects, quartz or pyrex ampules filled with acetylpropionyl peroxide solutions were placed into a modified detector of the BS-567A spectrometer with the temperature set in advance. The CPN effects were analyzed in the temperature range 193-313 K. The light of a DRSh-1000 mercury lamp was focused on the outer face of a quartz light guide, and with the aid of the latter it was guided to the side ...