Process for the manufacture of carboxylic peracids

In a continuous process for the manufacture of an olefin oxide from an olefin by reaction of the olefin with a carboxylic peracid comprising:

• (a) preparing the carboxylic peracid by reaction, in a reaction mixture, of the corresponding carboxylic acid with hydrogen peroxide in the presence of a catalyst and in the presence of an inert organic liquid which is contained in an organic phase and is a solvent for the peracid and is capable of forming a heterogeneous azeotrope with water, said organic liquid having a higher boiling point that that of the olefin and the olefin oxide, does not form an azeotrope with the olefin and the olefin oxide, and of which the possible azeotropes with the carboxylic acid and the carboxylic peracid have a higher boiling point than that of the olefin and the olefin oxide, removing water present in the reaction mixture by distillation of the water/organic liquid azeotrope, and maintaining a sufficient amount of water in the reaction mixture to allow the formation of an aqueous phase which is separate from the organic phase which contains the organic liquid and the carboxylic peracid;
• (b) withdrawing part of the reaction mixture of step (a), and then separating the aqueous phase from the organic phase, by decantation, of the part of the reaction mixture which has been withdrawn;
• (c) introducing the separated aqueous phase of step (b) into the reaction mixture of step (a);
• (d) reacting an olefin with the carboxylic peracid in the separated organic phase obtained in step (b) to form a reaction mixture containing unreacted olefin, olefin oxide, carboxylic acid and organic liquid;
• (e) subjecting the reaction mixture of step (d) to a separation to obtain unreacted olefin and an organic solution containing organic liquid, olefin oxide, and carboxylic acid;
• (f) distilling the organic solution obtained in step (e) to separate the olefin oxide from the carboxylic acid and organic liquid;
• and
• (g) feeding the separated carboxylic acid and organic liquid of step (f) to step (a).