Org. Synth. 1974, 54, 33
DOI: 10.15227/orgsyn.054.0033
TRIMETHYLENE DITHIOTOSYLATE AND ETHYLENE DITHIOTOSYLATE
[Benzenesulfonothioic acid, 4-methyl-, S,S'-1,3-propanediyl and S,S'-1,2-ethanediyl esters]
Submitted by R. B. Woodward
1, I. J. Pachter
2, and Monte L. Scheinbaum
3.
Checked by P. A. Rossy and S. Masamune.
1. Procedure
Caution! This procedure should be carried out in a hood to avoid inhalation of hydrogen sulfide.
A. Potassium thiotosylate. A solution of 64.9 g. (1.00 mole) of 86.5% potassium hydroxide (Note 1) in 28 ml. of water is cooled in an ice bath, saturated with hydrogen sulfide, and flushed with nitrogen to ensure complete removal of excess hydrogen sulfide (Note 2) and (Note 3). The freshly prepared potassium hydrosulfide solution is diluted with 117 ml. of water and stirred under nitrogen at 55–60° before 95.3 g. (0.500 mole) of finely ground p-toluenesulfonyl chloride (Note 3) is introduced in small portions at a uniform rate so that the reaction temperature is maintained at 55–60° (Note 2). A mildly exothermic reaction ensues, and the solution becomes intensely yellow. After about 90 g. of the tosyl chloride has been introduced, the yellow color disappears, and the dissolution of the chloride ceases. The reaction mixture is rapidly filtered with suction through a warmed funnel, and the filtrate is cooled several hours at 0–5°. The crystals of potassium thiotosylate are filtered, dissolved in 200 ml. of hot 80% ethanol, filtered hot to remove traces of sulfur, and cooled several hours at 0–5°. The recrystallized salt is filtered and air-dried, providing 48–55 g. (42–49%) of white crystals.
B.
Trimethylene dithiotosylate. To
150 ml. of 95% ethanol containing
10–20 mg. of potassium iodide is added
40 g. (0.18 mole) of potassium thiotosylate and
20 g. (0.10 mole) of 1,3-dibromopropane (trimethylene dibromide) (Note 4). The mixture is refluxed with stirring for 8 hours in the dark and under
nitrogen. The reaction mixture is cooled to ambient temperature, diluted with an equal volume of cold water, and agitated. After decantation of the supernatant liquid, the residual honeylike layer of product is washed with three 200-ml. portions of cold water, once with
100 ml. of cold 95% ethanol, and once with
100 ml. of cold absolute ethanol. The crude product
(Note 5) is dissolved in
10 ml. of acetone, diluted with
80 ml. of hot absolute ethanol, and stirred under
nitrogen at 0°. The oil which separates is redissolved by the addition of a minimum amount
(ca. 5 ml.) of acetone. Seed crystals are introduced
(Note 6), and the mixture is stirred for 1 hour at 0° under
nitrogen and stored at −30° for several hours. The microcrystalline product is collected by filtration and weighs
20.2 g., m.p.
63.5–65.0°. Three recrystallizations from nine parts
(180 ml.) of ethanol give
17.2 g. (
41%) of white needles, m.p.
66–67° (Note 7). During the recrystallizations some of the material oils out when the solution is cooled to room temperature. The supernatant liquid is decanted, seeded, and stored at −30° for several hours. The oil is not further purified. The recrystallized material is chemically pure for further use [
Org. Synth., Coll. Vol. 6, 590 (1988)].
C. Ethylene dithiotosylate. To 200 ml. of ethanol containing 10–20 mg. of potassium iodide is added 45.3 g. (0.200 mole) of potassium thiotosylate and 18.8 g. (0.100 mole) of 1,2-dibromopropane. The mixture is refluxed with stirring for 8 hours in the dark and under a nitrogen atmosphere. The solvent is removed, and the resulting white solid is washed with a mixture of 80 ml. of ethanol and 150 ml. of water. After decantation, the solid is washed three times with 50-ml. portions of water and recrystallized from approximately 150 ml. of ethanol, yielding 28.7 g. of crude product, m.p. 72–75°. Three recrystallizations from a mixture of ethyl acetate and ethanol afford 24 g. (60%) of white crystals, m.p. 75–76° (Note 8).
2. Notes
1.
Potassium hydroxide pellets of reagent grade commonly available, such as that from Fisher Scientific Company, contain 10–15% water. The checkers used the amount calculated on the basis of 86.5%, as specified.
2.
Hydrogen sulfide is undesirable because its presence can lead to the formation of
potassium p-toluenesulfinate. The latter can be formed by the desulfurization of thiotosylate by
hydrogen sulfide generated in the reaction of
potassium hydrosulfide with the tosyl chloride. Attention should be directed toward control of the reaction temperature so that
hydrogen sulfide is rapidly removed, thereby ensuing survival of the S-S bond of the thiotosylate.
p-Toluenesulfinate ion can displace bromide to form stable sulfones which are less soluble in common solvents, such as
benzene, than
trimethylene dithiotosylate. Therefore, purification of the dithiotosylate contaminated with the sulfones is difficult to achieve by fractional recrystallization.
3.
The
p-toluenesulfonyl chloride should be free of
p-toluenesulfonic acid, otherwise
potassium p-toluenesulfonate will be formed and result in the formation of tosylates, rather than thiotosylates. The reagent used by the checkers was obtained from British Drug Houses Ltd. and was purified by washing
benzene solution of the tosyl chloride with
5% aqueous sodium hydroxide, drying with
magnesium sulfate, and distilling under reduced pressure, b.p.
146° (15 mm.).
44.
Trimethylene dibromide, available from Eastman Organic Chemicals, was distilled prior to use (b.p.
167–168°).
5.
The checkers found that the crude oily product crystallizes after storage for a few days under
nitrogen at −30°. Some of this solid was saved and used as seed crystals.
6.
The submitters reported that seed crystals were obtained by column chromatography, using 40 parts by weight of Woelm
neutral alumina (activity grade one) and
benzene elution. The center cuts of m.p.
65° or higher were combined and recrystallized from nine parts of
ethanol to give white needles, m.p.
67°. Two recrystallizations of chromatographed gave
trimethylene dithiotosylate, m.p.
67.5°.
7.
The purified
trimethylene dithiotosylate exhibits IR bands (CHCl
3) at 3030 (w), 2930 (w), 1590 (w), 1490 (w), 1440 (w), 1410 (w), 1325 (s), 1300 (m), 1180 (w), 1140 (s), 1075 (s), 1015 (w), and 810 (m) cm
−1. The
1H NMR spectrum (CDCl
3 included signals at δ 1.98 (quinlet,
J = 7 Hz., 2H, CH
2C
H2CH
2), 2.43 (s, 6H, 2 C
H3), 2.97 (t,
J = 7 Hz., 4H, C
H2CH
2C
H2), 7.30 (d,
J = 9 Hz., 4H), and 7.75 (d,
J = 9 Hz., 4H). Analysis calculated for C
17H
20O
4S
4: C, 49.01; H, 4.84; S, 30.79. Found: C, 49.13; H, 4.81; S, 30.51 (submitters). Found: C, 48.71; H, H, 4.64; S, 30.45 (checkers). The checkers found that the product exhibited a single peak on a
3 ft. × 1/8 in. Waters Associates Analytical Liquid Chromatographic column, packed with Durapak-Carbowax 400/Poracil C.
Chloroform was used as the eluting solvent.
8.
The
1H NMR spectrum (CDCl
3) has absorptions at δ 2.47 (s, 6H, 2C
H3), 3.31 (s, 4H, 2C
H2), 7.48 (complex in,
J = 9 Hz., 4H) and 7.97 (d,
J = 9 Hz., 4H). Analysis calculated for C
16H
18S
4O
4: C, 47.73; H, 4.51; S, 31.86. Found: C, 47.89; H, 4.44; S, 32.22.
3. Discussion
Although it has been long known that
trimethylene dithiotosylate can be prepared by the reaction of thiotosylate ion with
trimethylene dibromide,
5 6 various difficulties are associated with the preparation. These problems are to a considerable extent related to the mode of preparation and the resultant purity of
potassium thiotosylate. The thiotosylate salt must be free of tosylate and
p-toluenesulfinate impurities, otherwise side products such as tosylates or sulfones will form. One such by-product,
tosyltrimethylene thiotosylate, CH3C6H4SO2(CH2)3SSO2C6H4CH3, m.p.
92°, was isolated from contaminated samples of
trimethylene dithiotosylate. It is products such as these, that make crystallization of the dithiotosylate difficult. The procedure described herein serves as a reliable technique for minimizing these experimental difficulties. More recently, it has been shown
7 that
trimethylene dithiotosylate can be prepared easily by the reaction of
tosyl chloride and
1,3-propanedithiol in
pyridine. This procedure, however, is unchecked.
Trimethylene dithiotosylate can react with activated methylene groups, enamines, or hydroxyethylene derivatives of carbonyl compounds to form dithiane derivatives. In this context,
trimethylene dithiotosylate has been employed in the preparation
8 and modification
9 10 of several steroids. It has also been used in the synthesis of alkaloids,
11 12 13 10-membered ring lactones,
14 and vernolepin analogues.
15 Ethylene dithiotosylate undergoes similar reactions, forming dithiolanes.
3,16
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
Benzenesulfonothioic acid, 4-methyl-, S,S'-1,3-propanediyl
S,S'-1,2-ethanediyl esters
ethanol (64-17-5)
Benzene (71-43-2)
ethyl acetate (141-78-6)
sodium hydroxide (1310-73-2)
chloroform (67-66-3)
hydrogen sulfide (7783-06-4)
1,2-dibromopropane (78-75-1)
trimethylene dibromide,
1,3-dibromopropane (109-64-8)
potassium iodide (7681-11-0)
nitrogen (7727-37-9)
sulfur (7704-34-9)
acetone (67-64-1)
pyridine (110-86-1)
potassium hydroxide (1310-58-3)
potassium hydrosulfide (1310-61-8)
magnesium sulfate (7487-88-9)
p-toluenesulfonic acid (104-15-4)
1,3-propanedithiol (109-80-8)
tosyl chloride,
p-Toluenesulfonyl chloride (98-59-9)
ethylene dithiotosylate
trimethylene dithiotosylate (3866-79-3)
potassium thiotosylate
tosyltrimethylene thiotosylate
potassium p-toluenesulfonate
potassium p-toluenesulfinate
p-toluenesulfinate
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