THERMAL DECOMPOSITION OF ACETYL PROPIONYL PEROXIDE
1725
in the yield of the alkanes may be an increase in their
solubility as the gas pressure in the ampule grows;
this trend is the most pronounced in the initial period
of thermolysis.
and placed in an NMR ampule with the outer diameter
1
of 5 (for recording the H NMR spectra) and 10 mm
(for recording the 13C NMR spectra). With each in-
sert, the NMR spectrum was recorded in the quantita-
tive mode. The relative error in the yield of the prod-
ucts averaged over three measurements was 8%.
It should be noted in conclusion that we detected
neither alcohols no ethers; this fact indicates that the
methyl and ethyl radicals do not add to the solvent
molecules to a noticeable extent.
1
As internal reference in the H NMR spectra we
used CHD COCD (isotope impurity in CD COCD ),
2
3
3
3
1
3
2
.05 ppm, quintet, and in the C NMR spectra, the
solvent signal:
Thus, peroxide I decomposes in acetone at rates
comparable with the rates of thermolysis in alcohols,
yielding a large set of products. In the examined tem-
perature range, the solvent molecules act as efficient
donors of D atoms, transforming into acetylmethyl-d5
radicals which recombine to a significant extent with
the radicals generated from the peroxide.
1
30.2 ppm (CD ). In the H NMR
C
3
spectra, we observed the characteristic proton signals
of peroxide I ( , ppm): 2.17 s [3H, CH C(O)O], 2.47
3
q (2H, CH ), 1.22 t (3H, CH ), and in the proton-
2
3
13
decoupled C NMR spectra, the singlets ( , ppm)
C
at 170.5 [C(O)O], 167.0 [C(O)O], 24.1 (CH ), 16.7
2
[
CH C(O)O], and 9.6 (CH ).
3
3
EXPERIMENTAL
REFERENCES
Peroxide I was prepared as described in [11]. The
content of available oxygen, determined by potentio-
metric titration, was 99.5%.
1
2
. Bagdasar’yan, Kh.S. and Milyutinskaya, R.I., Zh. Fiz.
Khim., 1963, vol. 27, no. 3, p. 420.
. Bagdasar’yan, Kh.S. and Milyutinskaya, R.I., Prob-
lemy mekhanizma khimicheskikh reaktsii (Problems
of the Mechanism of Chemical Reactions), Kiev:
Akad. Nauk Ukr. SSR, 1954, p. 88.
We studied 0.1 and 0.5 M solutions of I in ace-
tone-d (weight fraction of the main substance 99.5%,
6
degree of deuteration 99%). The qualitative and quan-
titative compositions of the products were determined
3
4
5
. Leffler, J.E. and Petropoulos, C.C., J. Am. Chem. Soc.,
1
13
1
from the H and C NMR spectra. The H NMR
spectra were measured on BS-567A and AM-360
1
957, vol. 79, no. 12, p. 3068.
. Leffler, J.E. and Wilson, A.F., J. Org. Chem., 1960,
vol. 25, no. 3, p. 424.
spectrometers operating at 100 and 360 MHz, respec-
tively. The 13C NMR spectra were taken on BS-567A
. Dutka, V.S., Tsvetkov, N.S., and Markovskaya, R.F.,
Kinet. Katal., 1982, vol. 23, no. 5, p. 1071.
and BS-587A spectrometers operating at 25 and
2
0 MHz, respectively. To study the effects of chemi-
1
13
cally induced nuclear polarization in the H and
C
6. Edwards, F.G. and Mayo, F.R., J. Am. Chem. Soc.,
1950, vol. 72, no. 3, p. 1265.
NMR spectra, 0.5 M solutions of I in sealed ampules
were placed in the BS-567A NMR probe preheated to
7. Skakovskii, E.D., Stankevich, A.I., Lamotkin, S.A.,
Tychinskaya, L.Yu., and Rykov, S.V., Zh. Obshch.
Khim., 1996, vol. 66, no. 6, p. 881.
3
60 K, and after a 120-s period the accumulation was
started. The number of accumulated scans sufficient
to obtain an acceptable spectrum was several tens for
8
. Skakovskii, E.D., Stankevich, A.I., Lamotkin, S.A.,
Tychinskaya, L.Yu., and Rykov, S.V., Zh. Obshch.
Khim., 2001, vol. 71, no. 4, p. 659.
1
13
H and 1000 for C.
To analyze the reaction products, solutions of I
9
. Skakovskii, E.D., Lamotkin, S.A., and Tychin-
skaya, L.Yu., Zh. Prikl. Spektrosk., 1997, vol. 64,
no. 3, p. 306.
were sealed in glass inserts with inner diameters of
1
13
2
.6 mm for H NMR and 6.0 mm for C NMR, so
that the gas volume did not exceed 10% of the liquid
volume. Under such conditions, all the gaseous com-
pounds formed by thermolysis of the peroxide virtual-
ly fully remained in the solution, which allowed their
quantitative analysis. The thermolysis was performed
in an oil thermostat at 323, 333, 343, 353, 363, and
10. Antonovskii, V.L., Organicheskie perekisnye initsia-
tory (Organic Peroxy Initiators), Moscow: Khimiya,
1972, p. 308.
11. El’nitskii, A.P., Ol’dekop, Yu.A., Bezborodov, V.S.,
Stankevich, A.I., Glazkov, Yu.V., and Skakov-
skii, E.D., Vestsi Akad. Navuk Bel. SSR, Ser. Khim.
Navuk, 1976, no. 2, p. 58.
3
73 K. At definite intervals, the inserts (three for each
temperature point) were removed from the thermostat
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004