9
52 J ournal of Chemical and Engineering Data, Vol. 45, No. 5, 2000
the embedded intrinsic strain Γortho(hydroxyl) ) 7.6 kJ‚mol-1
of catechol itself {calculated from ∆ H° (g) of catechol and
the sum of the aforementioned increments for the benzene
ring}. Comparison of the strains of alkylbenzenes and
catechol allowed the derivation of the effects of non-nearest-
neighbor interactions of alkyl substituents on the benzene
ring with the OH group directly. We calculated the differ-
para-, and meta-positions of alkylcatechols in comparison
with the case of alkyl-substituted phenols.1 Thus, no new
,2
f
m
parameters are needed for the prediction of the ∆
f
m
H° (g) of
similar shaped alkylcatechols by using the group-additive
ortho
procedure (exception for the intrinsic strain Γ
) 7.6 kJ ‚mol of catechol itself).
(hydroxyl)
-
1
ences ∆∆H
m
(strain) between individual strains for each
Liter a tu r e Cited
alkylcatechol and the sum of strain of the appropriate
alkyl-substituted benzene plus the intrinsic strain of cat-
echol (Table 7). These values ∆∆H (strain) were inter-
m
preted as the sum of excess interactions of alkyl substit-
uents on the benzene ring with the OH group.
The values for the pairwise interactions of a para- or
meta-methyl substituent with the hydroxyl group in meth-
(
(
(
1) Verevkin, S. P. Thermochemistry of Phenols. Quantification of
the Ortho-, Para-, and Meta-interactions in Tert-alkyl Substituted
Phenols. J . Chem. Thermodyn. 1999, 31, 559-585.
2) Verevkin, S. P. Thermochemistry of phenols: buttress effects in
steric hindered phenols. J . Chem. Thermodyn. 1999, 31, 1397-
1416.
3) Verevkin, S. P. Substituent effects on the benzene ring. Prediction
of the thermochemical properties of alkyl substituted hydroquino-
nes. Phys. Chem. Chem. Phys. 1999, 1, 127-133.
ylcatechols indicate (Table 7) a very weak destabilization
(4) Verevkin, S. P. Ph.D. Thesis, Minsk State University, Minsk,
1984.
(
about 0.5 kJ ‚mol-1 to 1.5 kJ ‚mol ) in accordance with the
-1
1
9
(5) Nesterova, T. N.; Verevkin, S. P.; Rempel, R. D.; Merdzanov, V.
R.; Roshupkina, I. Yu. Thermodynamic princyples of the tran-
salkylation of sterically hindered phenols. Zh. Prikl. Khim.
(Leningrad) 1990, 63, 1771-1775; CA 113:230728.
results for the methyl- and ethyl-substituted phenols. The
same trends were observed for the para- and meta-pairwise
interactions of isopropyl and tert-butyl substituents with
the hydroxyl group in alkyl-substituted catechols (Table
(
6) Ribeiro da Silva, M. D. M. C.; Ribeiro Da Silva, M. A. V.
Enthalpies of combustion of 1,2-dihydroxybenzene and of six alkyl
substituted 1,2-dihydroxybenzenes, J . Chem. Thermodyn. 1984,
16, 1149-1155.
-
1
7
). The similar weak destabilization of (1.7 kJ ‚mol to 3.9
-1
kJ ‚mol ) was also detected in para- and meta-alkylphenols
with secondary12 and tertiary1 alkyl substituents. Taking
(7) Steele, W. V.; Chirico, R. D.; Knipmeyer, S. E.; Nguyen, A. Vapor
Pressure, Heat Capacity, and Density along the Saturation Line,
Measurements for Dimethyl Isophthalate, Dimethyl Carbonate,
1,3,5-Triethylbenzene, Pentafluorphenol, 4-Tert-Butylcatechol,
R-Methylstyrene, and N,N′-Bis(2-hydroxyethyl)ethylenediamine.
J . Chem. Eng. Data 1997, 42, 1021-1036.
into account the average experimental uncertainties of the
-
1
values of enthalpies of formation of (2.0 kJ ‚mol , no
correction terms were necessary for the application of the
f
m
group-contribution correlation for ∆ H° (g) of the para-
(8) Hubbard, W. N.; Scott, D. W.; Waddington, G. Experimental
Thermochemistry; Rossini, F. D., Ed.; Interscience: New York,
and meta-alkyl-substituted catechols.
1
956; pp 75-127.
The ortho interactions of the methyl or isopropyl group
with the hydroxyl group in the alkylcatechols seem to be
negligible (Table 7) within the boundaries of experimental
(
9) Atomic weights of the elements. Pure Appl. Chem. 1994, 66,
2
423-2444.
(
10) Hemminger, W. F.; Cammenga, H. K. Methoden der Thermischen
-
1
uncertainties of (2 kJ ‚mol . This conclusion agrees with
the absence of ortho interactions of primary and secondary
alkyl substituents with the hydroxyl group in alkylphenols.
The para and meta interactions of the tert-butyl group
with the hydroxyls derived from 4-tert-butylcatechol led to
Analyse; Springer: Berlin, 1989.
(
11) Chickos, J . S.; Hosseini, S.; Hesse, D. G.; Liebman, J . F. Heat
Capacity Corrections to a Standard State: A Comparison of New
and Some Literature Methods for Organic Liquids and Solids.
Struct. Chem. 1993, 4, 271-278.
(
12) Verevkin, S. P. Determination of the ortho-, para-, and meta-
interactions in secondary-alkylphenols from thermochemical mea-
surements. Ber. Bunsen-Ges. Phys. Chem. 1998, 102, 1467-1474.
-1
a destabilization of 8 kJ ‚mol (Table 7). The similar weak
-
1
-1
destabilization of (2 kJ ‚mol to 3 kJ ‚mol ) was also
(13) CODATA Key Values for Thermodynamics; Cox, J . D., Wagman,
detected in para and meta tertiary alkylphenols.1
D. D., Medvedev, V. A., Eds.; Hemisphere: New York, 1989.
(
14) Olofsson, G. Combustion calorimetry; Sunner, S., Mansson, M.,
The ortho interactions of the tert-butyl group with the
hydroxyl derived from 3-tert-butylcatechol and 3,5-di-tert-
butylcatechol led to a meaningful destabilization of (13 to
Eds.; Pergamon: New York, 1979; Chapter 6.
(15) Liebman, J . F.; Greenberg, A. Strained Organic Molecules;
Organic Chemistry Series 38; Academic Press: New York, 1978.
(16) Schleyer, P. v. R.; Williams, J . E.; Blanchard, K. B. The evaluation
of strain in hydrocarbons. The strain in adamantane and its
origin. J . Am. Chem. Soc. 1970, 92, 2377-2386.
(17) Benson, S. W. Thermochemical Kinetics; Wiley: New York, 1976;
p 274.
18) Beckhaus, H.-D. Force Field for the Calculation of Structure and
Enthalpy of Formation of Alkylbenzenes. Chem. Ber. 1983, 116,
86-96.
19) Pedley, J . P.; Naylor, R. D.; Kirby, S. P. Thermochemical Data of
Organic Compounds, 2nd ed.; Chapman and Hall: London, 1986.
20) Verevkin, S. P. Thermochemical Properties of Branched Alkyl
substituted Benzenes. J . Chem. Thermodyn. 1998, 30, 1029-1040.
-
1
1
8) kJ ‚mol
(Table 7) due to steric repulsion of the
hydrogen by the alkyl substituent. This destabilization is
about the same as that of the ortho interaction of the tert-
ortho
alkyl group with the OH group Γ
(t-alkyl) ) 12.5
(
-
1
kJ ‚mol (mean value from mono-ortho-substituted phe-
1
2
nols ). The “buttress” interaction energy among the tert-
butyl and the hydroxy groups in their adjacent OH-OH-
tert-butyl position on the benzene ring is not distinguishable
within the boundaries of the experimental uncertainties.
Quantitative analysis of the pairwise interactions of
substituents on the benzene ring in alkylcatechols dem-
onstrated that there are no peculiarities in the interaction
energy among the alkyl and hydroxyl groups in the ortho-,
(
(
Received for review April 17, 2000. Accepted J une 26, 2000.
J E0001126