Patent GB-435494-A (GB)
Title: A process for converting unsaturated primary or secondary alcohols into their corresponding unsaturated carbonyl compounds
IPC: C07C45/00
Filed: 1934-04-24
Abstract: Unsaturated aldehydes and ketones are produced by treating unsaturated primary or secondary alcohols having a branched chain with dehydrogenating catalysts at above 250 DEG  C., preferably at 300--550 DEG  C.  The alcohols may be substituted with alkoxy, aryl, aryloxy, aralkyl, or aralkoxy groups, which may be further substituted.  A large number of primary and secondary alcohols containing a tertiary carbon atom are mentioned as starting materials.  The process may be effected at atmospheric or slightly higher pressure, but preferably under reduced pressure, and the reaction vapours may be fractionated to separate the less volatile alcohol from the aldehyde or ketone produced.  The usual dehydrogenation catalysts may be used such as activated copper, cobalt, iron, platinum, palladium, zinc, cadmium, manganese, lead, tin, silver, brass, brass spelter, zinc sulphide, zinc, manganous, stannous, cadmium, and non-reducible or difficultly reducible oxides, silver-zinc and silver-arsenic alloys.  Silver may be activated by amalgamating the surface with mercury and heating to remove the mercury, and it may be revivified after use by a similar treatment. Zinc sulphide may be produced by heating zinc in sulphuretted hydrogen.  The initial material may be freed from sulphur and halogens by passing the vapour over such metals as can be used as catalysts for the reaction but at lower temperatures or higher velocities than would effect the dehydrogenation.  If the alcohol has a tertiary carbon atom adjacent to the double bond, the temperature for the dehydrogenation may be higher than 600 DEG  C.  In examples: (1) isobutenol is passed over brass spelter in a copper tube, yielding methyl acrolein; (2) 2-methyl butene-1-ol-3 is converted into methyl isopropenyl ketone; (3) and (4) isobutenol is passed over active copper yielding methyl acrolein and isobutyraldehyde; (5) the alcohol CH2 = C (CH3).CHOH.C6H5, (made from methyl acrolein and phenyl magnesium bromide) is passed over brass spelter yielding isopropenyl phenyl ketone; (6) 2-methyl butene-2-ol-4 is converted into b -b -dimethyl acrolein in a similar manner.  The products may be utilized as resin components alone or with aldehydes, ketones, phenols, amines, ethers or the like, or may be used to introduce alkenyl groups into organic compounds by condensation or with organo-metallic compounds, or may be oxidized to the corresponding acids.  The Specification as open to inspection under Sect. 91 is not limited to the treatment of alcohols having a branched chain, and includes the treatment of allyl alcohol at 300--550 DEG  C. to produce acrolein; of butene-1-ol-3 with a brass spelter catalyst at 550 DEG  C. to produce methyl vinyl ketone; of cinnamyl alcohol at 550 DEG  C. with a brass spelter catalyst to produce cinnamic aldehyde; and mentioned also as initial materials alcohols of the following formul : CH2 = CH.CHOH.CH3, CH2 = CH.CHOH.C2H5, CH2 = CH.CHOH.C3H7, CH2 = CH.CHOH.C4H9, CH3.CH = CH.CH2OH, CH3.CH = CH.CHOH. CH3 and their homologues.  This subject-matter does not appear in the Specification as accepted.ALSO:Unsaturated aldehydes and ketones are produced by treating unsaturated primary or secondary alcohols having a branched chain with dehydrogenating catalysts at above 250 DEG  C., preferably at 300--550 DEG  C.  The alcohols may be substituted with alkoxy, aryl, aryloxy, aralkyl, or aralkoxy groups, which may be further substituted.  A large number of primary and secondary alcohols containing a tertiary carbon atom are mentioned as starting materials.  The process may be effected at atmospheric or slightly higher pressure, but preferably under reduced pressure, and the reaction vapours may be fractionated to separate the less volatile alcohol from the aldehyde or ketone produced.  The usual dehydrogenation catalysts may be used such as activated copper, cobalt, iron, platinum, palladium, zinc, cadmium, manganese, lead, tin, silver, brass, brass spelter, zinc sulphide, zinc, manganous, stannous, cadmium, and non-reducible or difficulty reducible oxides, silver-zinc and silver-arsenic alloys.  Silver may be activated by amalgamating the surface with mercury and heating to remove the mercury, and it may be revivified after use by a similar treatment. Zinc sulphide may be produced by heating zinc in sulphuretted hydrogen.  The initial material may be freed from sulphur and halogens by passing the vapour over such metals as can be used as catalysts for the reaction but at lower temperatures or higher velocities than would effect the dehydrogenation.  If the alcohol has a tertiary carbon atom adjacent to the double bond, the temperature for the dehydrogenation may be higher than 600 DEG  C.  In examples (1) isobutenol is passed over brass spelter in a copper tube, yielding methyl acrolein; (2) 2-methyl butene-1-ol-3 is converted into methyl isopropenyl ketone; (3) and (4) isobutenol is passed over active copper yielding methyl acrolein and isobutyraldehyde; (5) the alcohol CH2--C (CH3) , CHOH , C5H6 (made from methyl acrolein and phenyl magnesium bromide) is passed over brass spelter yielding isopropenyl phenyl ketone; (6) 2-methyl butene-2-ol-4 is converted into b -b -dimethyl acrolein in a similar manner.  The products may be utilized as resin components alone or with aldehydes ketones, phenols, amines, ethers or the like, or may be used to introduce alkenyl groups into organic compounds by condensation or with organometallic compounds, or may be oxidized to the corresponding acids.  The Specification as open to inspection under Sect. 91 is not limited to the treatment of alcohols having a branched chain, and includes the treatment of allyl alcohol at 300--550 DEG  C., to produce acrolein; of butene-1-ol-3 with a brass spelter catalyst at 550 DEG  C., to produce methyl vinyl ketone; of cinnamyl alcohol at 550 DEG  C., with a brass spelter catalyst to produce cinnamic aldehyde; and mentions also as initial materials alcohols of the following formulae CH2 = CH--CHOH--CH3CH2=CH--CHOH--C2H5, CH2=CH.CHOH.C3H7, CH2= CH--CHOH--C4H9, CH3--CH=CH--CH2CH, CH3--CH=CH--CHOH--CH3 and their homologues.  This subject-matter does not appear in the Specification as accepted.