Synlett 2011(13): 1947-1948  
DOI: 10.1055/s-0030-1260969
SPOTLIGHT
© Georg Thieme Verlag Stuttgart ˙ New York

Sodium Dithionite

Xiao-Nan Zhang*
The College of Chemistry & Material Science, Hebei Normal University, Shijiazhuang 050016, P. R. of China
e-Mail: zhangxn0911@163.com;
Further Information

Publication History

Publication Date:
21 July 2011 (online)

Introduction

Sodium dithionite (also known as sodium hydrosulfite) is a versatile, inexpensive, safe and readily available reagent, which has been employed for more than 70 years. It has been used in biochemistry for the reduction of a variety of coenzymes and enzymes, and in organic synthesis to reduce several types of functional groups, such as aldehydes, ketones, imines, pyrazine, vinyl sulfones, nitro [¹] and azo groups, [²] oximes, [³] enones, [4] quinones, [5] and azides. [6] It was also found to be an efficient reagent for the reductive displacement of iodine [7] and reductive coupling of benzylic and allylic halides. [8] It has been also used as radical initiator to promote coupling of CF3CHClBr with 1,3,5-trimethoxybenzene, [9] the addition of 1-bromo-1-chloro-2,2,2-triuoroethane to the terminal double bond of allylbenzenes, [¹0] addition reaction of peruoroalkyl iodides with allenes, [¹¹] the reaction of polyfluoroalkyl iodides with alkenes, [¹²] addition of dialkyl phosphonodifluoromethyl radical onto unsaturated ketones, [¹³] fluoroalkylation of porphyrins [¹4] and vinyl ethers. [¹5] This reagent is found to be a useful reagent in the intramolecular Marschalk cyclization [¹6] and Claisen rearrangement. [¹7]

Sodium dithionite is now commercially available, but can also be prepared readily by the reaction of sodium bisulfite with zinc. [¹8] It is obtained as a white crystalline powder with a weak sulfurous odor. This compound is stable under most conditions, but it will decompose in hot water and in acid solutions.

Scheme 1