VERFAHREN ZUR HERSTELLUNG VON 2,5-DIMETHYL- BZW. 2,5-DIETHYL-1,4;3,6-DIANHYDROSORBITOL.

摘要

Prodn. of 2,5-dialkyl-1,4:3,6-dianhydrosorbitols (I) is effected by alkylating 1,4:3,6-dianhydrosorbitol (II) in the presence of an aq alkali and a tert. alcohol solvent. Pref. alkylation is effected with an alkyl iodide, dialkyl sulphate or alkyl tosylate at 50-120 deg.C in the presence of 40-60% aq. NaOH or KOH and t-BuOH. (II) is formed in situ by dehydration of sorbitol. In an example, a mixt. of 292.3g (II) and 800 ml t-BuOH was stirred at 55-65 deg.C while adding simultaneously 572g of 50% aq. NaOH and 631 aq. dimethyl sulphate. The mixt. was stirred at 60 deg.C for 3 hr, distd. to remove t-BuOH, diluted with H2O and extracted with CH2Cl2. The extract was dried, evapd. and distd. to give 324g (93%) of 2,5-dimethyl-1,4:3,6-dianhydrosorbitol, b.pt. 118-120 deg.C/20 mbar.