J . Org. Chem. 2000, 65, 2319-2321
2319
Th er m a l Decom p osition Rea ction of Aceton e Tr ip er oxid e in
Tolu en e Solu tion
Gladys N. Eyler,* Carmen M. Mateo, Elida E. Alvarez, and Adriana I. Can˜izo
Laboratorio de Quı´mica, Facultad de Ingenier´ıa, Universidad Nacional del Centro de la Provincia de
Buenos Aires, Avda. del Valle 5737, (7400) Olavarr´ıa, Repu´blica Argentina
Received September 15, 1999
The thermal decomposition reaction of acetone cyclic triperoxide (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-
hexaoxacyclononane, ACTP) in the temperature range of 130.0-166.0 °C and an initial concentration
of 0.021 M has been studied in toluene solution. The thermolysis follows first-order kinetic laws
up to at least ca. 78% acetone triperoxide conversion. Under the experimental conditions, a radical-
induced decomposition reaction as a competing mechanism may be dismissed, so the activation
parameters correspond to the unimolecular thermal decomposition reaction of the ACTP molecule
[∆Hq) 41.8 ((1.6) kcal mol-1 and ∆Sq ) 18.5 ((3.8) cal mol-1K-1]. Analysis of the reaction products
are not enough to elucidate the real mechanism for the thermolysis of the acetone triperoxide in
toluene solution.
Sch em e 1
In tr od u ction
The chemistry of organic peroxides, which entails the
synthesis, characterization, and transformation of de-
rivatives of hydrogen peroxide, has a long history and
strong tradition.1,2 The unusual reactivity of peroxides
is generally attributed to weakness of the O-O bond
linkage and hence the case with which it is homolytically
cleaved. Cyclic di- and triperoxides derived from aliphatic
ketones which were prepared in this laboratory are the
object of numerous studies related to their application
as initiators for the polymerization of vinyl monomers.
Up to this moment, DEKTP3,4 (R ) R′ ) C2H5; 3,3,6,6,9,9-
hexaethyl-1,2,4,5,7,8-hexaoxacyclononane, Scheme 1) and
3,6-di-tert-butyl-3,6-dimethyl-1,2,4,5-tetraoxacyclohex-
ane are currently of special interest for the radical
polimerization of styrene at high temperatures. The
effects of the nature of these peroxide initiators on
polystyrene conversion and molecular weight are being
evaluated.5
acteristics of the respective molecule’s substituents. The
absence of a significant solvent effect on the products of
the thermal decomposition reaction of CHTP6 and DE-
KTP4 suggest that the product-forming step and the rate-
determining step are separated events. Thus, the rate-
determining step is the biradical (dialkoxy radical)
formation by homolytic cleavage of one of the O-O bonds
(eq 1).
Simultaneously with the studies related to the poten-
tial application of cyclic peroxides as initiators of polym-
erization, we have been investigating the thermal de-
composition reactions in solution of other members of this
family of compounds. The kinetic of the triperoxanes
(Scheme 1) thermal decomposition reaction for cyclohex-
anone triperoxide (R-R′ ) -(CH2)5-; 3,6,9-tricyclohexy-
lidene-1,2,4,5,7,8-hexaoxacyclononane, CHTP)6 and DE-
KTP4 have been studied, and it was demonstrated that
the different products obtained are related to the char-
It is reasonable to assume that the biradical recombi-
nation7 to rebuild the triperoxide molecule in a cage
reaction (eq 1) is a fast, nondetermining process. On the
other hand, the biradical formed can react with the
solvent and/or decompose thermally to generate several
different product sets and free radicals derived from
â-scission reaction (C-C and C-O bond ruptures).
In this work, we report the thermal decomposition
reaction of acetone cyclic triperoxide (R ) R′ ) CH3,
3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexaoxacyclononane,
ACTP) in toluene solution under experimental conditions
where a radical-induced decomposition reaction as a
competing mechansim may be dismissed. A comparison
with kinetic data from the thermal decomposition reac-
tion of ACTP in acetone8 is included.
* To whom correspondence should be addressed. Tel: 54-2284-
45105516. Fax: 54-2284-450628. E-mail: neyler@fio.unicen.edu.ar.
(1) McCullough, K. J .; Morgan, A. R.; Nonhebel, D. C.; Pauson, P.
L.; White, G. J . J . Chem. Res. Synop. 1980, 34, M 0601. (b) McCullough,
K. J .; Morgan, A. R.; Nonhebel, D. C.; Pauson, P. L. Ibid. 1981, 35, M
0629; 36, M 0651.
(2) Adam, W.; Hadjiarapoglou, L. P.; Curci, R.; Mello, R. In Organic
Peroxides; Ando, W., Ed.; J ohn Wiley & Sons: Chichester, England,
1992; Chapt. 4.
(3) Eyler, G. N.; Can˜izo, A. I.; Alvarez, E. E.; Cafferata, L. F. R.
Tetrahedron Lett. 1993, 34 (11), 1745.
(4) Eyler, G. N.; Can˜izo, A. I.; Alvarez, E. E.; Cafferata, L. F. R. An.
Asoc. Quı´m. Argent. 1994, 82 (3) 175.
(5) Morales, G.; Eyler, G. N.; Can˜izo, A. I., to be published.
(6) Sanderson, J . R.; Story, P. R. J . Org. Chem. 1974, 39 (24), 3463.
(7) Benson, S. W. In Thermochemical Kinetics; Wiley: New York,
1968; p 69.
(8) Mateo, C. M.; Eyler, G. N.; Alvarez, E. E.; Can˜izo, A. I.
Informacio´n Tecnolo´gica 1998, 9 (2), 19.
10.1021/jo991459i CCC: $19.00 © 2000 American Chemical Society
Published on Web 03/28/2000