Patent GB-996505-A (GB)
Title: Preparation of olefins
IPC: C07C1/32
Filed: 1963-03-14
Abstract: Compounds of the general formula R1OAIR2 (wherein R1 and R are both alkyl) are prepared by reacting an alkenyl ether containing the group <FORM:0996505/C2/1> with an aluminium compound of the general formula R2AIR3 (wherein R is alkyl and R3 is hydrogen or a radical <FORM:0996505/C2/2> wherein R4 and R5 are hydrogen or alkyl and may be the same or different).  Reaction may occur at room temperature to 130 DEG  C., preferably in presence of a hydrocarbon solvent, e.g. iso-octane, having a boiling-point intermediate between that of the olefin produced and the alkenyl ether used, the reaction taking place at the boiling-point of the reaction mixture, while adding small portions of the aluminium compound to the alkenyl ether solution. Specified alkenyl ethers are vinyl ethers, propenyl-ethyl-ether, pentenyl-ethyl-ether and compounds wherein the double bond of the alkenyl ether group is in a ring, e.g. alkoxy cyclohexenes. Specified aluminium compounds used are diethyl aluminium monohydride, di-isoamyl aluminium monohydride, diisobutyl aluminium monohydride and trialkyl aluminium, e.g. tri-isobutyl aluminium.  The examples describe the preparation of diisobutyl aluminium iso-butoxide, diisobutyl aluminium 2-ethylhexoxide and diisobutyl aluminium ethoxide.ALSO:Olefins are prepared by reacting an alkenyl ether containing the group <FORM:0996505/C4-C5/1> (where R1 is an alkyl group) with an aluminium compound of the general formula R2AlR3 (wherein R is an alkyl radical and R3 is hydrogen or a radical of the general formula <FORM:0996505/C4-C5/2> wherein R4 and R5 are the same or different and are hydrogen atoms or alkyl groups). When R3 is not hydrogen, a mixture of olefins is produced.  Reaction may occur at room temperature to 130 DEG  C. and preferably the reaction is carried out by adding small portions of the aluminium compound to a solution of the alkenyl ether in a hydrocarbon solvent having a boiling point intermediate between that of the olefin produced and the alkenyl ether used, the reaction taking place at the boiling point of the reaction mixture so that the olefin produced distills off. Specified alkenyl ethers are vinyl ethers, propenyl-ethyl-ether, pentenyl-ethyl-ether and compounds wherein the double bond of the alkenyl ether group is in a ring, e.g. alkoxycyclohexenes. Specified aluminium compounds used are aluminium diethyl monohydride, aluminium di-isoamyl monohydride, aluminium di-isobutyl monohydride and aluminium trialkyls, e.g. aluminium tri-isobutyl.  The examples describe the preparation of (1) a mixture of ethylene and isobutylene from vinyl iso-butyl ether and aluminium tri-iso-butyl; (2) ethylene from vinyl iso-butyl ether and aluminium di-isobutyl monohydride; (3) ethylene from 2-ethyl hexyl vinyl ether and aluminium diisobutyl monohydride; (4) propylene from ethyl propenyl ether and di-isobutyl monohydride in presence of iso-octane as hydrocarbon solvent; (5) pentene from pentenyl ethyl ether and di-isobutyl monohydride in presence of iso-octane; and (6) cyclohexane from 1-ethoxy-1-cyclohexene and aluminium di-isobutyl monohydride in presence of isooctane.