Patent GB-763066-A (GB)
Title: Process for the manufacture of monomeric or polymeric unsaturated ethers
IPC: C08F16/12
Filed: 1953-07-21
Abstract: Polymeric or monomeric unsaturated ethers (see Group IV (b)) are obtained by subjecting an acetal to the action of heat within the body of a chemically inert liquid having a boiling point above the boiling point of the acetal.  The heat treatment may be carried out in the presence of a surface active contact material which may if desired be impregnated with an additional acetal splitting catalyst. The catalyst-auxiliary liquid mixture used for the production of one unsaturated ether can be used successively for the production of different unsaturated ethers. A current of inert gas, e.g. nitrogen, may be used to carry the acetal into the auxiliary liquid and to assist in removing the fission products as they are formed.  The production of the polymeric ethers is favoured by using appropriate surface-active contact materials and maintaining high temperatures. Examples are given for the splitting of butyraldehyde diethyl acetal at 220 DEG  C. in the presence of Tonsil to yield monomeric and polymeric ethyl crotyl ether, and of 1 : 1 : 3-triethoxy butane in the presence of Tonsil, also in the absence of a catalyst, to yield polymeric butadienyl ethyl ether diethyl acetal.  In each of the examples paraffin oil is used as the auxiliary liquid and the reaction vessel is a vertical electrically heated glass tube closed at the bottom and provided with a Claisen attachment, the acetal being introduced through an inlet tube near the bottom of the vessel in an atmosphere of nitrogen under pressure and the heated portion of the tube being charged with the auxiliary liquid and contact material (if used).  Specificatio 724,012 and German Specifications 560,354 and 843,696 are referred to.ALSO:Monomeric or polymeric unsaturated ethers (see Group IV (a)) are obtained by subjecting an acetal to the action of heat within the body of a chemically inert auxiliary liquid having a boiling point above the boiling point of the acetal.  The heat treatment may be carried out in the presence of a surface-active contact material which may, if desired, be impregnated with an additional acetal-splitting catalyst.  The catalyst-auxiliary liquid mixture used for the production of one unsaturated ether can be used successively for the production of different unsaturated ethers. A current of iner gas, e.g. nitrogen, may be used to carry the acetal into the auxiliary liquid and to assist in removing the fission products as they are formed.  Examples are given for the splitting of (1) butyraldehyde dimethyl acetal to form crotyl methyl ether; (2) butyraldehyde diethyl acetal to form crotyl ethyl ether in monomeric and polymeric form; (3) butyraldehyde dibutyl acetal to form monomeric crotyl n-butyl ether; (4) 1 : 1 : 3 triethoxy butane to yield monomeric and polymeric butadienyl ethyl ether; and (5) acetaldehyde diethyl acetal to form monomeric vinyl ethyl ether.  In the examples paraffin oil is used as the auxiliary liquid and the reaction vessel is a vertical electrically heated glass tube closed at the bottom and provided with a Claisen attachment.  The acetal is introduced through an inlet tube near the bottom of the vessel in an atmosphere of nitrogen under pressure and the heated portion of the tube is charged with the auxiliary liquid and contact material (if used). Specified contact materials and catalysts are active carbon, Tonsil and active carbon impregnated with sodium ammonium acid phosphate.  Acetaldehyde dibutyl acetal is also referred to as a starting material.  Specification 724,012 and German Specifications 560,354 and 843,696 are referred to.