generate more toluenepyrosulfonic acid (7). Experimentally, the
related reaction of toluene with acetylsulfonic acid (9) appears
to follow second order kinetics and shows no significant kinetic
isotope effect when 4-deuterotoluene is used as the substrate,
and implies that sulfonation proceeds via attack of the toluene
ring at the sulfur atom, S8, of acetylsulfonic acid or toluene-
pyrosulfonic acid with simultaneous cleavage of the S8–O7
bond, where the displaced acetate or toluenesulfonate anion
respectively can facilitate the removal of the ring proton, H4Ј.
sulfonic acids using in these cases toluene (0.048 g, 0.53 mmol)
and either an aliquot (0.30 mL) of trifluoroacetic acid–
trifluoroacetic anhydride solution containing trifluoroacetyl-
sulfonic acid (0.12 g, 0.59 mmol), or an aliquot (0.31 mL) of
trimethylacetic acid–trimethylacetic anhydride solution con-
taining trimethylacetylsulfonic acid (0.097 g, 0.52 mmol).
References
1 W. H. de Groot, Sulphonation Technology in the Detergent Industry,
Kluwer, Dordrecht, 1991; H. Cerfontain, Mechanistic Aspects in
Aromatic Sulfonation and Desulfonation, Interscience, New York,
1968.
2 W. H. C. Rueggeberg, T. E. Sauls and S. L. Norwood, J. Org. Chem.,
1955, 20, 455.
3 N. H. Christensen, Acta Chem. Scand., 1964, 18, 954.
4 N. H. Christensen, Studies on Sulfonic Anhydrides, Glellerup,
Copanhagen, 1968, Chapters 2 and 3.
5 H. Cerfontain, A. Telder and L. Volbracht, Recl. Trav. Chim.
Pays-Bas, 1964, 83, 1103.
Experimental
NMR spectra were measured using a Bruker AC400 spec-
trometer, and analysed using the Bruker Xwinnmr software.
Diethyl ether used in the deuteration of 4-2H-toluene was dried
over calcium chloride and distilled before use.
4-2H-toluene
6 P. Guyer, R. Fleury and H. U. Reich, Chimia, 1968, 22, 40.
7 H. Cerfontain and C. W. F. Kort, Int. J. Sulfur Chem. C, 1971, 6,
123.
8 J. K. Bosscher and H. Cerfontain, Tetrahedron, 1968, 24, 6543.
9 J. K. Bosscher and H. Cerfontain, Recl. Trav. Chim. Pays-Bas, 1968,
87, 873.
10 J. K. Bosscher and H. Cerfontain, J. Chem. Soc. (B), 1968, 1524.
11 A. Koeberg-Telder and H. Cerfontain, Recl. Trav. Chim.
Pays-Bas, 1970, 89, 569; A. Koeberg-Telder and H. Cerfontain,
Recl. Trav. Chim. Pays-Bas, 1971, 90, 193; A. Koeberg-Telder and
H. Cerfontain, Recl. Trav. Chim. Pays-Bas, 1972, 91, 22.
12 K. Lammertsma and H. Cerfontain, J. Chem. Soc., Perkin Trans. 2,
1980, 2, 28.
13 C. W. F. Kort and H. Cerfontain, Recl. Trav. Chim. Pays-Bas, 1969,
88, 1298.
14 A. Koeberg-Telder and H. Cerfontain, J. Chem. Soc., Perkin Trans.
2, 1973, 633.
15 C. W. F. Kort and H. Cerfontain, Recl. Trav. Chim. Pays-Bas, 1967,
86, 865.
A solution of n-butyllithium (7.69 g, 120 mmol) in pentane
(60 mL) was slowly added to a stirred solution of 4-bromo-
toluene (10.2 g, 59.6 mmol) in diethyl ether (150 mL) main-
tained at approximately Ϫ78 ЊC during addition using an
acetone–dry ice bath. After addition was completed the reac-
tion mixture was allowed to warm to room temperature and
stirred for 3 h, then cooled again to Ϫ78 ЊC and deuterium
oxide (2.17 mL, 120 mmol) slowly added. The solution was
allowed to warm to room temperature and stirred for a further
3 h. Dilute hydrochloric acid (30 mL, 2 M, 60 mmol) was
added, and the solution stirred until there was no remaining
precipitate. The organic layer was, separated, washed with dis-
tilled water (30 mL), dried (MgSO4) and the excess solvent
removed by rotary evaporation to give 4-2H-toluene (4.05 g,
1
43.5 mmol) after distillation (bp 110–111 ЊC). H NMR (neat)
7.25 (d, H2, H6), 7.17 (d, H3, H5) ppm; J2,3 = 7.56 Hz.
16 C. W. F. Kort and H. Cerfontain, Recl. Trav. Chim. Pays-Bas, 1968,
87, 24; C. W. F. Kort and H. Cerfontain, Recl. Trav. Chim. Pays-Bas,
1969, 88, 860.
17 D. W. Roberts, Jorn. Com. Esp. Deterg., 1995, 26, 369.
18 J. O. Morley and D. W. Roberts, J. Org. Chem., 1997, 62, 7358.
19 M. J. S. Dewar and W. Thiel, J. Am. Chem. Soc., 1977, 99, 4899.
20 M. J. S. Dewar, E. G. Zoebisch, E. F. Healy and J. J. P. Stewart,
J. Am. Chem. Soc., 1985, 107, 3902.
Acetylsulfonic acid (9)
Sulfuric acid (4.41 g, 45 mmol) was slowly added to a mixture
of acetic anhydride (9.58 g, 94 mmol) and glacial acetic acid
(5.64 g, 94 mmol) maintained below 25 ЊC during the addition
(ice-bath). The reagent was used without any further work-up.
21 J. J. P. Stewart, J. Comput. Chem., 1989, 10, 209.
22 MOPAC 93 (J. J. P. Stewart, copyright Fujitsu Limited, Tokyo,
Japan, 1993) obtained from QCPE, Department of Chemistry,
Indiana University, Bloomington, Indiana 47405, USA.
23 M. J. S. Dewar and Y.-C. Yuan, Inorg. Chem., 1990, 29, 3881.
24 See for example W. J. Hehre, L. Radom, P. v. R. Schleyer and
J. A. Pople, Ab Initio Molecular Orbital Theory, John Wiley and
Sons, New York, 1986.
Trifluoroacetylsulfonic (10) and trimethylacetylsulfonic acids
(11)
These were prepared in a similar way by adding sulfuric acid
(4.41 g, 45 mmol) either to a mixture of trifluoroacetic
anhydride (19.8 g, 94 mmol) and trifluoroacetic acid (10.7 g,
94 mmol), or to a mixture of trimethylacetic anhydride (17.48 g,
94 mmol) and trimethylacetic acid (9.58 g, 94 mmol).
25 M. F. Guest, P. Sherwood, GAMESS, An ab initio program, The
Daresbury Laboratory, Warrington, UK.
26 See C. Wohlfarth, CRC Handbook of Chemistry and Physics,
eds. D. R. Lide, H. P. R. Frederiske, CRC Press, Boca Raton,
Florida, 1998, 78th edition, pp. 6–139.
27 J. O. Morley, Int. J. Quantum Chem., 1998, 66, 141.
28 J. O. Morley and M. H. Charlton, Int. J. Quantum Chem., 1995, 55,
361.
29 SYBYL Version 6.2, Tripos Inc., 1699 S. Hanley Road, St. Louis,
Missouri, 63144-2913, USA.
30 J. W. Viers, J. C. Schog, M. D. Stovall and J. I. Seeman, J. Comput.
Chem., 1984, 5, 598.
31 S. Miertus, E. Scrocco and J. Tomasi, J. Chem. Phys., 1981, 55, 117.
32 L. M. Stock and H. C. Brown, Advances in Physical Organic
Chemistry, ed. V. Gold, Academic Press, London, 1963, Vol. 1, p. 50.
33 E. A. Robinson and V. Silberberg, Can. J. Chem., 1966, 44, 1437.
34 E. A. Jeffrey and D. P. N. Satchell, J. Chem. Soc., 1962, 1187, 1913.
35 L. J. Tanghe and R. J. Brewer, Anal. Chem., 1968, 40, 350.
36 A. Casadevall, A. Commeyras, P. Paillons and H. Collet, Bull. Soc.
Chim. Fr., 1970, 5, 719.
37 A. Casadevall and A. Commeyras, Bull. Soc. Chim. Fr., 1970, 5,
1850.
38 J. O. Morley, J. Chem. Soc., Perkin Trans. 2, 1976, 1560;
C. Franchimont, Compt. Rend., 1881, 92, 1054; C. Franchimont,
Recl. Trav. Chim. Pays-Bas, 1881, 7, 26.
Kinetic experiments
An aliquot (0.30 mL) of the acetic acid–acetic anhydride solu-
tion containing acetylsulfonic acid (0.11 g, 0.82 mmol)
prepared as described above, was injected into an NMR tube
which was placed in a thermostated NMR probe and allowed to
warm to the specified temperature. The tube was then removed
from the probe, toluene (0.069 g, 0.75 mmol) was quickly
injected into the mixture, and the tube shaken vigorously and
placed back into the probe. The mixture was allowed to equili-
brate to the appropriate temperature for 2–3 minutes, and
spectra were then recorded every 10 minutes. The reactions
were investigated at temperatures of 22, 40, 50, 60 and 70 ЊC
(
0.5 ЊC). The rate of reaction was monitored by integrating
the 1H NMR resonances at 7.36 (m, H2, H4, H6) and 7.28 ppm
(m, H3, H5) for toluene, and at 7.51 (d, H2, H6), and 7.93 ppm
(d, H3, H5) for toluene-4-sulfonic acid. These resonances,
however, were found to vary slightly depending on both tem-
perature and the % conversion into product. A similar pro-
cedure was adopted for monitoring the reactions of the other
544
J. Chem. Soc., Perkin Trans. 2, 2002, 538–544