ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2019, Vol. 93, No. 1, pp. 23–27. © Pleiades Publishing, Ltd., 2019.
Russian Text © I.B. Abdrakhmanov, V.M. Sharafutdinov, A.G. Mustafin, Yu.S. Zimin, R.R. Daminev, 2019, published in Zhurnal Fizicheskoi Khimii, 2019, Vol. 93, No. 1, pp. 23–27.
CHEMICAL KINETICS
AND CATALYSIS
Effect of Solvents on Acid-Catalyzed Claisen Amino Rearrangement
in N-(1-Methyl-2-butenyl)aniline
I. B. Abdrakhmanova, V. M. Sharafutdinovb, A. G. Mustafinc, Yu. S. Ziminc,*, and R. R. Daminevb
aUfa Institute of Chemistry, Russian Academy of Sciences,
Ufa, 450054 Republic of Bashkortostan, Russia
bUfa State University of Petroleum Technology, Ufa, 450062 Republic of Bashkortostan, Russia
cBashkir State University, Ufa, 450076 Republic of Bashkortostan, Russia
Received February 13, 2018
Abstract—The effect solvents have on the processes of rearrangement and elimination in N-(1-methyl-2-
butenyl)aniline (I) in the presence of HCl is studied. It is shown that the dependence of the rearrangement
and elimination rate constants of (I) · HCl on the nature of solvents are described perfectly by the Koppel–
Palm equation, which considers both nonspecific and specific solvation. The inhibitory effect of solvent
nucleophilicity is explained by the complexation between (I) · HCl and solvent molecules. Analysis of the
(I) · HCl conversion products obtained in a mixed solvent (m-toluidine + nitrobenzene) demonstrates the
intermolecular transfer of the allyl moiety, confirming the formation of allyl cations in the Claisen amino
rearrangement.
Keywords: N-(1-methyl-2-butenyl)aniline, Claisen rearrangement, acidic catalysis, effect of solvents
DOI: 10.1134/S0036024418120026
INTRODUCTION
The kinetics of N-(1-methyl-2-butenyl)aniline
conversion was studied using the experiment-point
approach. Experiments were performed at 126°C in
The acid-catalyzed Claisen rearrangement in the
series of N-allylanilines is a convenient way of synthe-
sizing ortho-substituted arylamines [1]. A number of sealed glass ampoules (reaction mixture volume,
researchers [2–4] believe this reaction proceeds
according to the intramolecular 3,3-sigmatropic
mechanism. In [5, 6], we showed the mechanism of
rearrangement in N-(1-methyl-2-butenyl)aniline was
different than commonly believed. Relatively low acti-
vation enthalpy, positive activation entropy [5], and
the formation of para-products and cross rearrange-
ment products during the simultaneous conversion of
~1 mL). The catalyst (HCl) was introduced into the
reaction mixture in the form of hydrochloride of
compound I. The freshly prepared reaction mixture
was loaded in the ampules, which were then sealed
and placed into a thermostat. The temperature was
maintained with a precision of 0.2°C. The first
sample (the zero point) was taken after 2 min of heat-
two substrates [6] testify to the more complicated ing. The ampoule was cooled to 20°C and opened,
mechanism of this process.
after which excess triethylamine was added to convert
the hydrochlorides of aromatic amines into free
bases. The reaction mixture was subsequently ana-
lyzed via gas–liquid chromatography, using pentade-
cane as an internal standard. The other ampoules
were taken at specific time intervals and analyzed in
the same way.
It is known that concerted reactions depend weakly
on the nature of solvents [7]. To study the rearrange-
ment in N-(1-methyl-2-butenyl)aniline, we studied
the kinetic patterns of this reaction in different sol-
vents in the presence of HCl.
EXPERIMENTAL
N-(1-Methyl-2-butenyl)aniline (I) and 2-(1-
methyl-2-butenyl)aniline (II) were synthesized
according to [8] and [9], respectively. The physico-
chemical characteristics of the synthesized com-
pounds corresponded to the literature data. Freshly
distilled solvents were used in all the experiments.
RESULTS AND DISCUSSION
In [5], it was shown that the conversion of N-(1-
methyl-2-butenyl)aniline in the presence of HCl
obeys the laws of the parallel first-order reaction
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