process for purification of 1,4 - dioxane - 2.5 - dion or (d, l - or l, l - 3.6 - of - 1,4 - dioxane - 2.5 - dion

摘要

Purificn of opt. substd. 1,4-dioxan-2,5-dione derivs (I) by recrystallisation in organic solvents comprises treating (I) in concns. of 25-100g/100ml organic solvent with 5-12g weakly basic alkaline earth metal oxides and/or alkaline earth metal carbonates per 100g (I) for 10-60 min at the b.pt. of the solvent, and then isolating (I) conventionally by ' recrystallisation. The oxide is pref. magnesium or calcium oxide and the carbonate is of calcium carbonate. The organic solvent is pref. CHCl3, butyl ethanoate, ethyl ethanoate and/or methylene chloride. USE/ADVANTAGE - (I) can be polymerised to high molecular aliphatic polyesters which are biodegradable and completely resorbable. They can be used as carriers for pharmaceuticals in delayed release systems and in surgical sewing materials. The process gives highly pure (4), essentially free from carboxyl gps which can be polymerised in high yields to high molecular aliphatic polyesters (I) of insufficient purity gives polyesters of lower molecular mass.