Patent GB-1012475-A (GB)
Title: Allenic compounds and process of manufacturing them
IPC: C07C45/67
Filed: 1961-12-13
Abstract: The invention consists per se of a compound of the Formula (I): <FORM:1012475/C2/1> in which R1 and R2, together with the carbon atom to which they are bonded, complete a carbocyclic ring, especially a 3-methyl-nor-bornan-2-yl, cyclohexyl, cyclopentyl or tetrahydrophenyl ring, R3 and R4 are each hydrogen or an alkyl group containing from one to seven carbon atoms and R5 is hydrogen or an alkyl group containing from one to four carbon atoms, or a compound of the above formula in which R1 and R2 are each an alkyl or an alkenyl group containing from one to seven carbon atoms, R3 and R4 together with the carbon atom to which they are bonded complete a carbocyclic ring, especially a cyclohexyl or cyclopentyl ring, and R5 is hydrogen or an alkyl group containing from one to four carbon atoms, or a compound of the above formula in which R1, R2, R3 and R4 are each hydrogen or an alkyl group containing from one to seven carbon atoms and R5 is an alkyl group containing from one to four carbon atoms.  The invention also includes a process wherein a compound of the Formula (II): <FORM:1012475/C2/2> is reacted in the presence of an acidic catalyst in a solvent of higher boiling point than their reactants and which boils at a temperature not higher than 250 DEG  C., with a compound of the Formula (III):  <FORM:1012475/C2/3> wherein R1 to R5 are as above defined, or when R1 or R2 represents an alkenyl group, the double bond in the compound of Formula (II) is in the alpha, beta-position to the CHO group.  The invention further includes a process for preparing a compound of Formula (I) as above defined or a compound of Formula (I) defined in the parent Specification 1 which comprises respectively reacting an aldehyde of the Formula (II) as above with an alcohol of Formula (III) as above, or an aldehyde of the Formula (II) defined in the parent Specification with an aldehyde is therein defined, said reacting being effected in the vapour phase in the presence of a siliceous catalyst or activated carbon, preferably impregnated with an acid reacting material.  The products can be converted to the corresponding 3,5-dienaldehyde by isomerization, or into a 3- or 4-olefinic aldehyde by partial hydrogenation, or into an alcohol corresponding to the starting material by reducing the CHO group of the aldehyde to a -CH2OH group, or alternatively to the corresponding carboxylic acid by oxidizing the -CHO group to a -COOH group.  The alcohols may be converted to esters, the carboxylic acids may be converted to a salt or a further ester. In the examples 2,2-dimethyl-4 - cyclohexylidene- and cyclopentylidene - 3-butyraldehyde, 2 - propadienyl - 3 - methyl - 2-norbornanecarboxaldehyde, 3 - methyl - 2-propadienyl - 2 - norbornane carboxaldehyde, 1 - propadienylcyclohexane carboxaldehyde, 1 - propadienylcyclopentane carboxaldehyde, 2 - ethyl - 2 - butyl - 3 - methyl - 3,4 - pentadienal, 2 - (1 - butenyl) - 2 - ethyl - 5 - methyl-3,4 - heptadienal, 1 - prodienyl tetrahydro benzaldehyde, are produced in the liquid phase process.  The conversion of the aldehyde to alcohol described in detail is effected using aluminium isopropoxide as the reducing agent. However, other alkoxides suggested include those of lithium, sodium, potassium, magnesium, stannic, zirconium, or titanium alkoxides. The corresponding acids may be prepared by the use of oxidizing agents known in the art or catalytically with air or oxygen or by disproportionation, care must however be taken to avoid reaction of the double bonds if mono-basic acids are desired. 2,2-dimethyl-3,4-pentadienal is also prepared by the vapour phase process using activated carbon as catalyst. 2,2 - dimethyl - 4 - cyclohexylidene - 3 - butenaldehyde is reduced with aluminium isopropoxide to 2,2 - dimethyl - 4 - cyclohexylidene-3-butenol. Named acids produced by the propargyl rearrangement are: 2-alkenyl 3-methyl-bicyclo (2,2,1)heptane-2-carboxylic acid and 4 - cyclohexyliden - 2,2 - dimethyl - 3-butenoic.