| 摘要 |
1,156,709. Polyethers prepared by intramolecular dehydration of diols. BADISCHE ANILIN- & SODA-FABRIK A.G. 16 Nov., 1966 [17 Nov., 1965], No. 51331/66. Heading C2C. [Also in Division C3] Polyethers are prepared by inter-molecular dehydration of alkane diols having from 5 to 12 carbon atoms and terminal hydroxyl groups at elevated temperatures in the presence of a solid, non-basic dehydration catalyst, resulting water being removed from the reaction zone at the rate at which it is formed. Suitable alkane diols, which preferably have an unbranched carbon chain, are pentanediol-(1,5), hexanediol- (1,6), octanediol-(1,8), decanediol-(1,10) and dodecanediol-(1,12) or mixtures thereof. Examples of suitable catalysts, which are preferably weakly acidic, are oxides of aluminium, thorium, tungsten, vanadium, bismuth, molybdenum, titanium, osmium and chromium, or mixtures thereof to which zinc oxide or cadmium oxide may be added; boric acid; boron phosphate; borates and phosphates, especially weakly acid phosphates; aluminas, kieselguhr, silica gel; and porous materials, e.g. pumice or active carbon, impregnated with sulphuric acid, phosphoric acid, boric acid, acid phosphates or acid-forming metal oxides. Chromates or chromites of alkaline earth or heavy metals can be added to activate the catalyst. The reaction is carried out at a temperature of from 200‹ to 400‹ C. at a pressure between 50 torr and 10 atmospheres and the residence period in the reaction zone is between 1 and 1800 seconds. Water is removed from the reaction zone by azeotropic distillation or by simultaneously passing an inert gas, e.g. nitrogen or hydrogen, and the diol over the catalyst. The diol is preferably not reacted to completion so that it may act as solvent for the polyether formed. The resulting polyethers preferably have molecular weights between 300 and 1500. |
