Sodium dithionite

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Description

Pale yellow powder that is used as a Reducing agent in dyeing Indigo and vat dyes. Sodium dithionite is also used to strip dyes from dyed textiles and reduce iron oxide stains to [[ferrous oxide|ferrous oxide]. Sodium dithionite was also used as a bleach for Leather and mechanical paper pulps but its use has declined in recent years due to poor color reversion properties (AIC Book and Paper Catalog).

Note: this is not the same compound as Sodium thiosulfate (Na2S2O3; also called sodium hyposulfite) that is used for fixation in photography.

Synonyms and Related Terms

sodium thiosulfite; sodium hydrosulfite; sodium sulfoxylate

Chemical structure

Sodium dithionite.jpg


Other Properties

Soluble in water (pH = 6.0-7.5 for 1-6% solution). Insoluble in ethanol.

Composition Na2S2O4
CAS 7775-14-6
Melting Point 52-55
Density 2.19
Molecular Weight mol. wt. = 174.1

Hazards and Safety

Fire risk in contact with moisture and air. Use dry sand to extinguish fires. Flash point=90 C

Contact causes irritation

Mallinckrodt Baker: MSDS

Additional Information

AIC Book and Paper Catalog, p.

Authority

  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 786
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
  • Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989
  • The Dictionary of Paper, American Paper Institute, New York, Fourth Edition, 1980
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 8771

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