Patent GB-611554-A (GB)
Title: Purification of anthracene
IPC: C07C7/14
Filed: 1946-05-01
Abstract: Crude anthracene is purified by subjecting it to at least two successive crystallization steps from cyclohexylamine.  The purified anthracene obtained is suitable for direct oxidation to anthraquinone.  The crude anthracene is heated with the cyclohexylamine under normal or elevated pressures to give complete or only partial solution of the solid.  Other solvents can be mixed with the cyclohexylamine and if water is present, a solvent which is non-miscible or only slightly miscible with water may be added and the water and added solvent removed by azeotropic distillation.  The filtrate and/or washings from the crystallization of one quantity of crude anthracene can be used instead of new cyclohexylamine for the first crystallization of a second quantity of crude anthracene, fresh solvent being used in the second crystallization only.  In examples: (1) and (2) crude anthracene is heated with cyclohexylamine to give complete solution which is then cooled and filtered.  The filter cake is washed with cyclohexylamine and then heated with a further quantity of cyclohexylamine to give complete solution which is cooled and filtered, the filter cake being finally washed with cyclohexylamine and then dried.  Increased anthracene recovery is obtained by partially evaporating the solvent from the first stage filtrates and washings by heating, then cooling, filtering and washing the impure anthracene which separates out and using it in a subsequent purification process instead of an equivalent quantity of crude anthracene; (3) a two-stage purification is made as in (1) and (2) and the undried filter cake then heated with a further quantity of cyclohexylamine, the solution cooled and filtered and the filter cake is washed with cyclohexylamine and finally dried.ALSO:Crude anthracene is purified by subjecting it to at least two successive crystallisation steps from cyclohexylamine.  The purified anthracene obtained is suitable for direct oxidation to anthraquinone.  The crude anthracene is heated with the cyclohexylamine under normal or elevated pressures to give complete or only partial solution of the solid.  Other solvents can be mixed with the cyclohexylamine and if water is present a solvent which is non-miscible or only slightly miscible with water may be added and the water and added solvent removed by azeotropic distillation.  The filtrate and/or washings from the crystallination of one quantity of crude anthracene can be used instead of new cyclohexylamine for the first crystallisation of a second quantity of crude anthracene, fresh solvent being used in the second crystallisation only.  In examples (1) and (2), crude anthracene is heated with cyclohexylamine to give complete solution which is then cooled and filtered.  The filter cake is washed with cyclohexylamine and then heated with a further quantity of cyclohexylamine to give complete solution which is cooled and filtered, the filter cake being finally washed with cyclohexylamine and then dried.  Increased anthracene recovery is obtained by partially evaporating the solvent from the first stage filtrates and washings by heating, then cooling, filtering and washing the impure anthracene which separates out and using it in a subsequent purification process instead of an equivalent quantity of crude anthracene; (3) a two-stage purification is made as in (1) and (2) and the undried filter cake then heated with a further quantity of cyclohexylamine, the solution cooled and filtered and the filter cake is washed with cyclohexylamine and finally dried.