Sodium Hydrosulfite, Sodium Dithionite
Sodium hydrosulfite (sodium dithionite, Na2S2O4) is an inexpensive and safe reducing agent, which for example enables the reduction of aromatic nitro and diazonium compounds to anilines.
Recent Literature
A highly efficient and versatile method for the synthesis of
benzimidazoles was achieved in one step via the Na2S2O4
reduction of o-nitroanilines in the presence of aldehydes.
D. Yang, D. Fokas, J. Li, L. Yu, C. M. Baldino, Synthesis,
2005, 47-56.
The hydrogenation of α,β-epoxy ketones can be mediated by a catalytic
amount of BNA+Br- using Na2S2O4
as primary reducing agent to form the corresponding β-hydroxy ketones in
high yield. A radical mechanism has been proposed.
H.-J. Xu, Y.-C. Liu, Y. Fu, Y.-D. Wu, Org. Lett.,
2006,
8, 3449-3451.
Various azobenzenes have been reduced to the corresponding hydrazines by using
an aqueous solution of sodium dithionite. The yield is generally excellent, but
two compounds, viz. 4,4-dimethoxyazobenzene and
2,2,4,4,6,6-hexamethylazobenzene, gave no hydrazine at all.
L. K. Sydnes, S. Elmi, P. Heggen, B. Holmelid, D. Malthe-Sørensen, Synlett, 2007,
1695-1696.
