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Tetrathiomolybdate mediated sulfur transfer; Dibenzyl disulfide

SyntheticPage 544
DOI: 10.1039/SP544
Submitted Mar 19, 2012, published Mar 26, 2012
Ramesha Ramakrishna (ramesha63@hotmail.com)
A contribution from ramesha


			Reaction Scheme: Tetrathiomolybdate mediated sulfur transfer

Chemicals Used

Ammonium tetrathiomolybdate, Aldrich
Acetonitrile, Lab grade
Benzyl triethyl ammonium chloride, Min 98%, lab grade
Diethyl ether, lab grade
Silicagel, coloum chromatograph grade

Procedure

To a 250 mL two necked flask was charged acetonitrile (100 mL), ammonium tetrathiomolybdate (14 g, 53 mmol), benzyltriethylammonium chloride (24 g, 106 mmol) under nitrogen atmosphere. The red colour solution was stirred for 15 min. To this solution, benzyl chloride (6.3 g, 50 mmol) was added slowly at room temperature in 5 min. The reaction mixture was stirred for 4-6 h until the disappearance of starting material by TLC. Acetonitrile was concentrated by vacuum to about 80%. To the black slurry, diethyl ether (75 mL) was added and filtered through a small pack of silica (about 35 g silica on a sintered filtration assembly). The black sludge was collected back in to the glass flask and, about 20 mL of acetonitrile was added and made the black mass into thick slurry and to this added diethyl ether (75 mL) and filtered again. This procedure repeated for 2 more times. The filtered ether layer was washed with water (200 mL) and dried over sodium sulphate. This diethyl ether solution was passed through a narrow path of silica gel (about 50 g on a sintered filtration assembly) and concentrated to give dibenzyldisulfide as the only product 5.30 g (86%).

Author's Comments

1. This reaction works for any alkyl or benzyl chloro or bromo leaving group.
2. Reaction is slow for secondary and do not work for tert- leaving group.
3. Mesylates and tosylates also works.
4. In most case the reaction is complete in 2-3 h and only single spot TLC is observed.
5. Aqueous workup is not done in the procedure.
6. Yield depends on how effectively one extracts product from the black molybdenum sludge.
7. There is no smell of thiol during or after the reaction.
8. The reaction should be carried under neutral condition. Acidic/basic cndition decampose tetrathiomolybdate

Data

1H NMR: (200 MHz, CDCl3): δ 7.28 (s, 10H), 3.60 (s, 4H)

13C NMR: (100 MHz, CDCl3): δ 137.24, 129.31,128.37,127.31,43.18

Mass (m/z): 246 (M+), 214, 182,121, 91


Lead Reference

Modified procedure of

A. R. Ramesha, Chandrasekaran S., Synthetic Communications, 1992, 22, 3277–3284.

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Keywords: aromatics/arenes, Disulfides, nucleophilic, substitution, sulphides, tetrathiomolybdate

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