[1041-16-3] · C18H15BS3 · Triphenyl Thioborate · (MW 338.35)
Alternate Names: phenyl thioborate; tris(phenylthio)borane.
Solubility: sol benzene, ether, acetone.4
Preparative Methods: can be made from Boron Triiodide and Diphenyl Disulfide;5 from Thiophenol and Boron Trichloride;6 from (phenylthio)borane trimer and thiophenol;7 or from Boron Trisulfide and thiophenol.2,8
Handling, Storage, and Precautions: sensitive to moisture and should be stored in a desiccator. Can be weighed out quickly in air, if humidity is low, but best handled in a dry box.2
Esters are converted into phenylthio esters by heating with phenyl thioborate in refluxing xylene (140 °C) (eq 1), but the same transformation can be done at room temperature with phenyl thioaluminate. With the aluminum reagent, a,b-unsaturated esters give products contaminated with the b-(phenylthio) ester, but the boron reagent does not suffer from this disadvantage (eq 2).
a,b-Unsaturated aldehydes and ketones form 1,3-bis(phenylthio)alkenes on treatment with phenyl thioborate (eq 3). The (phenylthio)alkenes are b-acyl vinyl anion equivalents (eq 4).
Philip L. Wickens & Derrick L. J. Clive
University of Alberta, Edmonton, Canada