3-(Trimethylsilyl)prop-2-ynyl p-toluenesulfonate

In the title compound, C13H18O3SSi, the SO3 group displays a partial rotational (ca 50°) disorder about the C—S bond, with relative proportions 0.7744 (13):0.2256 (13). This disorder also forces the propynyl CH2 group to be disordered.

In the title compound, C 13 H 18 O 3 SSi, the SO 3 group displays a partial rotational (ca 50 ) disorder about the C-S bond, with relative proportions 0.7744 (13):0.2256 (13). This disorder also forces the propynyl CH 2 group to be disordered.

Related literature
For information on the title compound, see: Westmijze & Vermeer (1979); Tanabe et al. (1995); Morales (1995 ales, 1995). It has been described as a colorless liquid at room temperature (Tanabe et al., 1995;Westmijze & Vermeer, 1979). Our initial synthesis, by treating 3-trimethylsilylpropargyl alcohol with freshly powdered KOH and freshly recrystallized p-toluenesulfonyl chloride in ether at -50°C, also yielded the desired sulfonate as a liquid. However, after several recrystallizations from hexanes, suitable single crystals were obtained as colorless needles with melting point 43-44°C.
3-Trimethylsilyl-2-propynyl p-toluenesulfonate contains a p-toluenesulfonate group with the S(O) 2 OCH 2 group partially (22.56 (13)%) disordered by rotation of ca 50° about the C-S bond. The disorder was modelled with constrained partial occupancy of two O 3 and two H 2 sites. The disordered O-C bond distances were restrained to be approximately equal (to within σ = 0.002 Å) to compensate for disorder of the C atom itself. The two partial S-O bonds average 1.574 (2) Å, and the four partial S═O bonds average 1.435 (1) Å.

Experimental
The title compound was prepared according to the procedure of Westmijze & Vermeer (1979): Commercially available 3-trimethylsilylpropargyl alcohol (5.13 g, 40.0 mmol) and freshly purified tosyl chloride (9.53 g, 50.0 mmol) were mixed in anhydrous diethyl ether under an Ar atmosphere. The mixture was cooled to -50 °C, and freshly powdered KOH (15.0 g, 268 mmol) was added at once under vigorous stirring. The temperature of the resulting thick mixture was slowly raised to 0°C , and the mixture was stirred at this temperature for 30 min. This mixture was poured onto water (200 ml), extracted with ethyl ether (3 τimes 50 ml), washed with water (100 ml), and concentrated under reduced pressure to give a light brown oil.
Atomic displacement parameters were constrained to be equal for the following disordered atom pairs: O1 and O1A, O2 and O2A, O3 and O3A, and interatomic distances C8-O1 and C8-O1A were restrained to be equal to within σ = 0.002.
All H atoms were placed in calculated positions, guided by difference maps, with C-H bond distances 0.95 (aromatic-H), 0.98 (methyl-H), and 0.99 (alkyl-H) Å, and displacement parameters U iso =1.2U eq (aromatic and alkyl C) and 1.5U eq (methyl-C), and thereafter refined as riding.