Process for preparing crystals of anhydrous sodium sulfide

Details Process for preparing crystals of anhydrous sodium sulfide Process for preparing crystals of anhydrous sodium sulfide

1989-05-26

1992-12-22

Straub, Gary P.

Chemistry: physical processes

Physical processes

Crystallization

23294R, 23304, 423203, 4235662, C01B 1722

Patent

active

051730880

ABSTRACT:
Disclosed is a process for preparing crystals of anhydrous sodium sulfide, the process being characterized in that the process comprises the steps of heating crystals of polyhydrate of sodium sulfide under a pressure of about 500 torr or less at a temperature varying not more than .+-.about 10.degree. C. from the phase transition point between polyhydrate crystals and monohydrate crystals of sodium sulfide for about 2 hours or longer and further heating the monohydrate under atmospheric or reduced pressure at about 90.degree. to about 200.degree. C. for about 2 hours or longer.

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Chemical Abstracts, p. 1939, Abstract No. 5606(6), Columbus, Ohio, US; B. P. Ershov et al.: "Obtaining chemically pure sodium sulfide. Preliminary communications", & J. Chem. Ind. 16, No. 2, 48-50 (1939) *Abstract*.
Chemical Abstracts, vol. 78, No. 22, Jun. 4, 1973, p. 137, Abstract No. 138433k, Columbus, Ohio, US; & SU-A-363 658 (Institute of Metallurgy and Ore Beneficiation, Acadmey of Sciences, Kazakh S. S. R.) Dec. 25, 1972.
Chemical Abstracts, vol. 68, No. 24, 1968, p. 10483, Abstract No. 108432k, Columbus, Ohio, US; N. I. Kopylov: "Sodium sulfide-water system and thermal dehydration of Na2S.9H20", ZH. Neorg. Khim. 13(2), 529-32 (1968) *Abstract*.
J. Chem. Soc. Dalton Trans., No. 3, 1986, pp. 469-475; J. Y. Andersson et al.: "Mechanisms and Kinetics of the thermal decomposition of sodium sulphide pentahydrate under controlled water vapour pressure".

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