Solvent-Free Synthesis of Thiophenol Using Uncatalyzed Transfer Hydrogenation

Abstract

Clean and sustainable transfer hydrogenation for aryl sulfonamides and sulfonyl chlorides is described. The protocol is chemoselective and uses neither catalyst nor solvent.

GRAPHICAL ABSTRACT

Keywords:

• Solvent-free
• thiophenol
• uncatalyzed transfer hydrogenation

ACKNOWLEDGMENTS

This work has been supported by the National Natural Science Foundation of China (20776127), the National Key Technology Research and Development Program (2007BAI34B07), and the Natural Science Foundation of the Zhejiang Province (Y4090045 and R4090358).

Notes

^a Reaction conditions: 4-methylbenzenesulfonamide (0.02 mol), hydrogen donor, solvent (15 mL or none), temperature (185 °C), reaction time (5 h).

^b Determined by GC methods using hexadecane as an internal standard.

^a Reaction conditions: 4-methybenzenesulfonyl (0.02 mol), hydrogen donor, solvent (15 mL or none), temperature (100 °C for 1 h and 180 °C for another 5 h).

^b Determined by GC methods using hexadecane as an internal standard.

^a Reaction conditions: Sulfonamide (0.1 mol), potassium formate (0.5 mol), without solvent, 200 °C, 7 h; sulfonyl chloride (0.1 mol), ammonium formate (0.5 mol), without solvent, 100 °C for 1 h and 200 °C for 6 h.

^b Yield of isolated product.