Discovery of practical production processes for arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides): Beginning of a new era of "super-trifluoromethyl" arene chemistry and its industry

Abstract

Various arylsulfur pentafluorides, ArSF(5), have long been desired in both academic and industrial areas, and ArSF(5) compounds have attracted considerable interest in many areas such as medicines, agrochemicals, and other new materials, since the highly stable SF(5) group is considered a "super-trifluoromethyl group" due to its significantly higher electronegativity and lipophilicity. This article describes the first practical method for the production of various arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides), from the corresponding diaryl disulfides or aryl thiols. The method consists of two steps: (Step 1) treatment of a diaryl disulfide or an aryl thiol with chlorine in the presence of an alkali metal fluoride, and (step 2) treatment of the resulting arylsulfur chlorotetrafluoride with a fluoride source, such as ZnF(2), HF, and Sb(III/V) fluorides. The intermediate arylsulfur chlorotetrafluorides were isolated by distillation or recrystallization and characterized. The aspects of these new reactions are revealed and reaction mechanisms are discussed. As the method offers considerable improvement over previous methods in cost, yield, practicality, applicability, and large-scale production, the new processes described here can be employed as the first practical methods for the economical production of various arylsulfur pentafluorides and their higher homologues, which could then open up a new era of "super-trifluoromethyl" arene chemistry and its applications in many areas.

Keywords: arylsulfur chlorotetrafluoride; arylsulfur pentafluoride; pentafluorosulfanyl; sulfur pentafluoride; super-trifluoromethyl.

Scheme 1

Preparation of ArSF₄Cl 2.

Scheme 2

Preparation of Ar(SF₄Cl)_n from Ar(SH)_n (n = 2, 3).

Scheme 3

Reaction mechanism for the formation of ArSF₄Cl.

Scheme 4

Reaction mechanism for the formation of trans and cis-ArSF₄Cl.

Scheme 5

Preparation of ArSF₅ with ZnF₂.

Scheme 6

Preparation of PhSF₅ with anhydrous HF.

Scheme 7

Preparation of 3a with HF–pyridine.

Scheme 8

Preparation of polyfluorinated ArSF₅.

Scheme 9

Preparation of aryl bis- and tris(sulfur pentafluorides), Ar(SF₅)_n (n = 2,3).