Patent GB-652809-A (GB)
Title: A process for the base-catalysed vapour-phase production of ethers from alcohols and olefins
IPC: C07C41/06
Filed: 1948-08-10
Abstract: Ethers are made by contacting saturated monohydric alcohols and mono-olefines, preferably having initial temperatures of not more than 350 DEG  C., both in the vapour phase at 100-400 DEG  C., and under pressure, preferably above 8 atmos., in the presence of non-volatile oxides or hydroxides of alkaline-reacting metals. Alkaline reacting metals are the light and heavy metals listed on the left-hand portion of the Periodic Table of the Elements on page 314 of the "Handbook of Chemistry and Physics," 29th Edtn., published by the Chemical Rubber Publishing Co.  For highest conversions the temperature of reaction should not be above about 300 DEG  C., desirably 190-210 DEG  C.  With the latter range pressures of 10-16 atmos. are quoted.  The process leads to the formation of practically no polymeric or other side reaction products.  The following are representative of many specified olefines:-propylene, isobutene, 2 - propyl - 2 - butene, 2 - hexene, 2,4,4 - trimethyl - 1 - butene and 2 - methyl - 1 - pentene.  Tertiary olefines having a critical temperature of not more than about 250 DEG  C. such as isobutene and 2-methyl-2-butene are preferred.  Mixtures of olefines, e.g. obtainable by the fractional distillation of cracking process effluents, may be used optionally with inert diluents such as saturated hydrocarbons or ethers.  In general alcohols with not more than 4 carbon atoms are preferred, e.g. methyl, ethyl, propyl, isopropyl, normal, secondary and tertiary butyl alcohols.  Alicyclic alcohols such as cyclo-butyl alcohol may also be used as may alcoholic mixtures and inert diluents such as saturated hydrocarbons and ethers.  Mixed hydroxides and oxides of the alkali and alkaline earth metals are preferred catalysts, e.g. an activated alkaline earth metal oxide, preferably magnesium oxide, impregnated with potassium or sodium hydroxide.  Preferably the mixture contains a major amount, e.g. about 90 per cent by weight, of oxide and a minor amount, e.g. about 10 per cent, of hydroxide.  Such a catalyst may be made by impregnating activated magnesia with potassium hydroxide dissolved in just enough water to dampen the magnesia and drying the compound at 120-150 DEG  C.  It is stated that propyl methyldiethylcarbinyl ether, ethyl diethylcarbinyl ether, isopropyl tertiary butyl ether, and ditertiary-butyl ether are respectively made from 2-ethyl-2-butene and propyl alcohol, 2-pentene and ethyl alcohol, isobutene and isopropyl alcohol and isobutene and tert.-butyl alcohol by methods corresponding to those of the examples, in which (1) isobutene and methyl alcohol are passed over the magnesia-KOH catalyst prepared as above, at 13 atmos., and 200 DEG  C., with a contact time of 7.5 mins., and reaction products including methyl tertiary butyl ether, are separated by distillation after water extraction of excess alcohol; and (2) 3-methyl-1-butene and ethyl alcohol are passed over a magnesia-NaOH catalyst at 13 atmos. and 200 DEG  C. to yield ethyl methylisopropylcarbinyl ether. Specification 393,753 is referred to.  The Specification as open to inspection under Sect. 91 is not restricted to mono-olefines or to saturated monohydric alcohols and specifies allyl and butenyl alcohols.  This subject-matter does not appear in the Specification as accepted.