PROCESS FOR THE MANUFACTURE OF ANTHRAQUINONE-1,8-DISULPHONIC ACID

摘要

1458250 Anthraquinone-1,8-disulphonic acid IMPERIAL CHEMICAL INDUSTRIES Ltd 7 Nov 1975 [5 Dec 1974] 52622/74 Heading C2C Anthraquinone - 1,8 - disulphonic acid is obtained by contacting a reaction product obtained by sulphonation of anthracene with a water-soluble Mg salt in aqueous medium whereby the Mg salt of anthracene-1,5-disulphonic acid is precipitated, separating off the precipitate, and subjecting the anthracene-1,8- disulphonic acid present in, or obtained from the residual acids to a two-stage oxidation process, the first stage under acid conditions and the second stage under alkaline conditions. Specified water-soluble Mg salts are MgCl 2 and MgSO 4 which latter compound may be prepared in situ from MgCO 3 or Mg(OH) 2 and excess H 2 SO 4 in the sulphonation mixture. After removal of the Mg salt of anthracene-1,5- disulphonic acid the anthracene-1,8-disulphonic acid may be isolated from the mother liquor by the addition of salt. The oxidizing agent used in first stage above may be aqueous HNO 3 , or alkali metal permanganate, dichromate or chlorate (optionally with V 2 O 5 ) in H 2 SO 4 , and the oxidizing agent used in the second stage may be alkali metal hypochlorite in caustic alkali.