公开(公告)号：DE2703282A1

公开(公告)日：1978-08-10

申请号：DE2703282

申请日：1977-01-27

Applicant: BASF AG

Inventor： KIENER VOLKER DIPL CHEM DR ,  AUTZEN HORST DIPL CHEM DR ,  KOESTER HARTWIG DIPL CHEM DR ,  WUNSCH GERD DIPL CHEM DR ,  OSTERTAG WERNER DIPL CHEM DR ,  SCHREINER SIEGFRIED DIPL CHEM ,  VOELKL ERFRIED DIPL CHEM DR ,  HETZEL ECKARD DIPL CHEM

IPC: C01B17/66

Abstract: Anhydrous sodium dithionite is prepd. by the action of SO2 on NaOOCH in excess and NaOH in a reaction medium formed of H2O and an organic solvent. Methyl formate is also added to the reaction mixt. in a proportion which is =15 wt. % w.r.t. the organic solvent, and pref. when the reaction mixt. contains >=66% of the theoretical amt. of SO2 to be used. The molar proportions of NaOH and SO2 do not exceed the ratio 1:2. The process gives increased yields of a purer and more stable sodium dithionite, with a better granules size distribution. Pref. the initial reaction mixt. contains all the NaOH required in the form of an aq. soln., possibly contg. a part of the NaOOCH and/or the SO2. The remaining NaOOCH and SO2, as well as the cH3OOCH, are then added to this initial reaction mixt.