Organic Process Research & Development 2002, 6, 234−237
Reactivity of Some Carboxylic Acids in Reactions with Some Epoxides in the
Presence Chromium (III) Ethanoate
Agnieszka Bukowska and Wiktor Bukowski*
Faculty of Chemistry, Rzeszo´w UniVersity of Technology, 35-959 Rzeszo´w, Poland
Abstract:
it is known that the rate of addition of a carboxylic acid
depends on the structure of oxirane. In particular, in the series
of reactions of aliphatic and aromatic monoglycidyl ethers
with caproic or capric acid in the presence of NaOH, the
rate constants of addition were found to increase slightly with
increase of the acceptor character of substituents at epoxy
rings.6 An opposite effect was observed in the system where
substituted glycidylamines reacted with acetic, benzoic, 3,5-
dinitrobenzoic, or tetrahydrobenzoic acid in chlorobenzene
solution in the presence of benzyldiethylamine.7,8 One should
note that the epoxy ring in glycidylamine is exceptionally
reactive. For example, N-ethyl-N-glycidylamine reacts with
benzoic acid in chlorobenzene ca. 100 times faster than
phenylglycidyl ether.9 Somewhat less reactive, but still much
more reactive than glycidyl ethers, are glycidyl esters. For
example, glycidyl benzoate reacts with benzoic and hexanoic
acid ca. 50-70 times faster than phenylglycidyl ether.7 For
glycidyl esters of substituted benzoic acids, an increase of
addition rate of carboxylic acids was observed with increas-
ing donor character of substituents, as for glycidylamines.
The reactivity studies for series of aliphatic and aromatic
carboxylic acids with respect to ethylene oxide in nitroben-
zene in the presence of the respective potassium carboxylates
that were carried out by Lebedev et al.10,11 at the beginning
of the 1960s revealed a clear effect of the strength of the
acids on addition rate. Separate linear dependences have been
found between pKa’s of acids in water and the logarithms
of rate constants of addition for aliphatic and aromatic
carboxylic acids. An increase of the reaction rate with the
strength of acid was observed also for the reaction of ethylene
oxide with acetic acid and its chloro derivatives in the
presence of tertiary amines in butanol,12 for the reaction of
ethylene oxide with aromatic carboxylic acids in the presence
of pyridine in some protic and aprotic solvents,13 or for the
addition of a series of aliphatic carboxylic acids to propylene
oxide in the presence of CH3COOK.14 Mallek et al.,13 as
Lebiedev et al.10,11 somewhat earlier, found Bro¨nsted-type
relationships in the systems they studied.
Reactivities have been compared of acetic, acrylic, and meth-
acrylic acid in reactions with epichlorohydrin, phenylglycidyl
ether, glycidyl acetate, and glycidyl methacrylate carried in the
presence of chromium (III) ethanoate. The acid reactivities
changed differently with respect to the oxirane series. The effect
of solvents on the reactions of acids with epichlorohydrin has
also been observed.
Introduction
Reactivity of epoxy compounds is related to the relatively
high stress within three-membered rings on one hand and,
on the other hand, to polarization of C-O bonds leading to
formation of partial charges on carbon and oxygen atoms of
magnitudes, depending on the kind of nearest neighbors of
epoxy group. Some electrophilic substances (e.g., protonic
acids or Lewis acids) may enhance the polarization and hence
affect the reactivity of epoxy group by interacting with the
electron pair of oxygen atom. The interactions may have
hydrogen-bonding, charge-transfer, or donor-acceptor char-
acteristics. Basic compounds (nucleophiles), however, may
affect the partially positively charged carbon atoms in epoxy
rings, thus facilitating ring-opening and further reactions of
epoxy compounds. Consequently, oxiranes undergo many
diversified chemical transformations,1-4 and reactions in-
volving oxiranes are catalyzed by many compounds, of both
acidic and basic character, as well as by acceptor-donor
substances.
From practical point of view, addition of carboxylic acids
to an epoxy group is an important reaction of oxiranes. One
of its applications is the addition of acrylic or methacrylic
acid to epoxy compounds, leading to formation of respective
hydroxyalkyl esters.5
The relative rate of addition of acids to oxiranes has been
studied many times in the past.6-19 From the published data
(1) Parker, R. E.; Isaacs, N. S. Chem. ReV. 1959, 59, 737.
(2) Rao, A. S.; Paknikar, S. K.; Kirtane, J. G. Tetrahedron 1983, 39(14), 2323.
(3) Gorzynski Smith, J. Synthesis 1984, 629.
The relative rate of addition of carboxylic acids to
oxiranes, however, cannot be related to their strength, as can
be deduced from the results obtained in the present work.
(4) Jacobsen E. N. Acc. Chem. Res. 2000, 33, 421.
(5) Bukowska, A.; Bukowski, W.; Galina, H. Wiad. Chem. 1997, 51(3-4), 217.
(6) Sorokin, M. F.; Gershanova, E. L. Kinet. Katal. 1967, 8(3), 512.
(7) Klebanov, M. S.; Kiriazev, F. Yu.; Tchervinskij, A. Yu.; Shologon, I. M.
Zh. Org. Khim. 1984, 20(11), 2407.
(8) Klebanov, M. S.; Kiriazev, F. Yu.; Karpov, O. N. Kinet. Katal. 1987, 28(6),
1493.
(9) Klebanov, M. S.; Kiriazev, F. Yu.; Shologon, I. M. Kinet. Katal. 1984,
25(4), 1004.
(13) Malek, J.; Silhavy, P. Collect. Czech. Chem. Commun. 1976, 41, 84.
(14) Chlebicki, J.; Zwiefka, A. Tenside Surf. Det. 1985, 22(3), 117.
(15) Bukowska, A.; Bukowski, W.; Mossety-Leszczak, B. J. Chem. Technol.
Biotechnol. 1999, 74(12), 1145.
(10) Guskov, K. A.; Lebedev, N. N. Trudy MChTI (in Russia) 1963, 42, 57.
(11) Lebedev, N. N.; Guskov, K. A. Kinet. Katal. 1964, 5(5), 787.
(12) Mares, F.; Hetflejs, J.; Bazant, V. Collect. Czech. Chem. Commun. 1969,
34, 3086.
(16) Jay, R. Anal. Chim. 1964, 36, 667.
(17) Bukowska, A.; Bukowski, W. J. Chem. Technol. Biotechnol. 1996, 67, 176.
(18) Bukowska, A.; Bukowski, W. J. Chem. Technol. Biotechnol. 1999, 74, 675.
(19) Bukowska, A.; Bukowski, W. Org. Process Res. DeV. 1999, 3(6), 432.
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Vol. 6, No. 3, 2002 / Organic Process Research & Development
10.1021/op010112q CCC: $22.00 © 2002 American Chemical Society
Published on Web 05/01/2002