Patent GB-435321-A (GB)
Title: Improvements in or relating to the manufacture of selenium compounds of the benzanthrone series
IPC: C09B3/06
Filed: 1934-03-19
Abstract: Selenium compounds of the benzanthrone series are obtained by heating an alkali metal selenide or polyselenide with a bz-1-halogen-benzanthrone or a substitution product thereof, in a diluent.  A lower temperature is required than when elementary selenium is employed, and the reaction may be controlled to produce benzanthronyl alkali selenide or dibenzanthronyl alkali selenide or dibenzanthronyl thronyl selenide, the former being obtained when an excess of alcohol as diluent and a short reaction time are employed, and the latter when excess of alkali selenide or polyselenide are employed.  The alkali selenides, which may be prepared in situ, may be obtained by treating selenium with sodium or potassium in a solvent or diluent such as alcohol, treating selenium with caustic alkali, aqueous or alcoholic, in presence of a reducing metal such as aluminium or magnesium, or heating selenium with phosphorus and decomposing the product with alkali. According to examples: (1) selenium is melted with red phosphorus, sodium hydroxide is added after cooling and bz-1-bromo-benzanthrone is boiled with the so-obtained solution of sodium polyselenide; the product after isolation and purification is bz - 1 : bz - 1<1> - dibenzanthronyl selenide; (2) freshly-prepared sodium selenide is added to an alcoholic solution of the above brom-derivative to give the same product; (3) sodium selenide prepared from sodium and selenium in alcohol is added to bz-1-bromobenzanthrone suspended in alcohol and heated to give a product the same as example 1, together with some bz-1 : bz-1<1>-dibenzanthronyl diselenide, which gives on mild alkali fusion, bz - 1 - benzanthronyl potassium selenide, or on acidification, bz-1-benzanthrone selenol which may be reconverted into the above-mentiond diselenide on oxidation; (4) a selenium solution obtained by treating selenium with caustic potash and aluminium with exclusion of air, is treated with bz-1-bromobenzanthrone, to give mainly bz - 1 - benzanthronyl hydrogen selenide which may be isolated or used directly for subsequent reactions, for example, by aeration to give the diselenide.  Specification 367,462 is referred to.  Substitution products of benzanthrone which may be employed are methoxy, halogen and nitro derivatives, the latter being reduced to an amino compound in the course of the reaction.ALSO:Alkali selenides are obtained: (1) by treating selenium with alkali metal in a solvent such as alcohol; (2) by treating selenium with aqueous or alcoholic caustic alkali in presence of a reducing metal such as aluminium or magnesium; and (3) by heating selenium with phosphorus and decomposing the product with alkali. According to examples, a sodium polyselenide solution is obtained by melting selenium with red phosphorus, cooling and adding caustic soda; sodium selenide is prepared from sodium and selenium in alcohol; and selenium is treated with caustic potash and aluminium in the absence of air.  Excess of selenium in any of these processes results in the formation of a polyselenide.