Dichloroselenious acid

Selenium oxychloride may be prepared by several methods (1) by passing chlorine gas into a suspension of selenium dioxide in carbon tetrachloride, (2) by heating thionyl chloride, SOCE, with selenium dioxide, (3) by dehydration of dichloroselenious acid, H2Se(CE)02, and (4) by fusion of selenium dioxide, selenium, and calcium chloride. 

The classical researches of Victor Lenher on selenium(IV) oxychloride (reviewed by Smith ) were begun about 1919 at the University of Wisconsin. Lenher suggested the following practical laboratory methods for the preparation of selenium(IV) oxychloride (1) union of selenium(IV) oxide and selenium(IV) chloride (2) partial hydrolysis of sele-nium(IV) chloride, and (3) dehydration of Se02 2HCl (dichloroselenious acid, H2Se02Cl2). ... 

Anhydrous Hydrogen Chloride. Since considerable quantities of hydrogen chloride are needed in the conversion of selenium(IV) oxide to dichloroselenious acid, the apparatus described by Maxson is modified as illustrated in Fig. 23. 

The species formed in solutions of selenium dioxide in hydrochloric acid (4-12 Af), often called dichloroselenious acid, is actually a hydrate of seleninyl chloride (SeOC ), as shown by Raman studies/ At higher [HCl] the pen-tachloroselenate(V) anion is formed ... 

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