| 摘要 |
<p>Cyclic ethers are produced by heating glycols or polyhydric alcohols combined with or mixed with metal oxides such as alkali and alkaline earth metal oxides, preferably in the presence of hydrochloric acid, and/or other condensing agents such as calcium chloride or sodium chloride. The reaction may be effected in presence of an inert liquid of high boiling-point such as tetrahydronaptthalene, decahydronaphthalene or diphenyl, and nitrogen, carbon dioxide or other gases or vapours may be passed through the reaction mixture to effect agitation. The reaction may be effected in presence of a liquid forming an azeotropic mixture with water or with the ether, and if desired the inert diluent may be one that can entrain the ether. Or an azeotroping substance may be added to the vapours leaving the reaction vessel so that the ether can be fractionally condensed while the water and entraining agent remain in the vapour state. Alternatively the ether may be separated by passing the vapours into a liquid maintained at a temperature between the boiling points of the ether and water, or into a liquid that will dissolve the ether but not water, or the vapours may be passed over water-binding substances, preferably after first fractionally condensing the bulk of the water. The vapours may be passed over substances such as sodium carbonate or calcium hydroxide to neutralize hydrochloric acid, or the neutralization may be effected after condensation. In examples, (1) a mixture of calcium glycerate and diphenyl is treated with hydrochloric and at 190-200 DEG C.; (2) a mixture of calcium glycerate and glycerol is heated at 240-280 DEG C. while stirring. Instead of glycerol, other polyhydric alcohols such as erythritol or ethers thereof containing at least two free hydroxy groups in the form of metal salts or mixtures with metal p oxides may be used. Or mixtures of salts of glycol and glycerol or of glycol and an ether of glycerol may be employed. Specification 396,761 is referred to.</p> |
