Patent GB-463959-A (GB)
Title: Process for the production of valuable carbonyl compounds
IPC: C07C45/52
Filed: 1935-10-07
Abstract: Unsaturated carbonyl compounds are manufactured by heating, e.g. to 100--250 DEG  C. or higher, a polyhydric alcohol containing at least three carbinol groups, one or more of which may be tertiary, in the presence of a solution or suspension of a catalyst consisting of a mineral acid and/or another compound having a mineral acid action under the reaction conditions, in a mutual solvent or dispersion medium for the polyhydric alcohol and the catalyst which is substantially inert under the conditions of the operation, if desired at superatmospheric pressure.  The carbonyl compounds are preferably removed as quickly as they are formed, e.g. by distillation, if desired together with an excess of water. Alternatively a mixture of alcohol and acid solution may be circulated through a heated tube and the hot reaction mixture passed into contact with some substance serving to condense the carbonyl compound to a product insoluble in the reaction mixture, which is then separated therefrom.  The solvent or dispersion medium employed may be water or an organic solvent or a mixture thereof, suitable organic solvents being organic acids, e.g. formic, acetic, propionic, butyric and isobutyric acids.  The alcohols treated are preferably those containing at least three vicinal carbinol groups, or those containing at least one tertiary carbinol group which may be vicinal to or separated from at least two other vicinal carbinol groups by one or a series of tertiary carbon atoms.  If the alcohol contains only tertiary carbinol groups (in which case the reaction involves a migration of one of the alkyl radicles) the carbinol groups need not be vicinal but may be separated by one or a series of tertiary carbon atoms. When the alcohol contains a primary carbinol group which is involved in the reaction, the product is usually an aldehyde but sometimes a mixture of aldehyde and ketone.  When only secondary or tertiary carbinol groups are involved, the product is usually a ketone, but sometimes a mixture of aldehyde and ketone.  Alcohols specified are: glycerol (which may be employed in the crude state, e.g. as the crude aqueous solution obtained in soap manufacture), 1 : 2 : 4-trihydroxybutane, b -methylglycerol, a -ethyl-b -methylglycerol, a -ethylglycerol, a -g -dimethyl glycerol, a -phenyl-b -methylglycerol, 1 : 2 : 3 trihydroxycyclohexane, b -(hydroxymethyl)-glycerol, and their homologues and substitution products.  Suitable catalysts are sulphuric, phosphoric, or hydrochloric acids, sodium bisulphate, zinc sulphate, and alkyl acid sulphates.  The products may be used as resin-forming bodies per se or after treatment with polymerizing agents, for solvent and extraction purposes, in pharmaceutical chemistry, and as intermediates in the preparation of organic chemicals, e.g. for the introduction of alkyl or alkenyl groups into organic compounds by condensation or by the use of organo-metallic derivatives.  They may be oxidized to the corresponding acids.  In examples: (1) an aqueous solution of glycerol is fed into the kettle of a pressure still containing dilute sulphuric acid and heated to 190 DEG  C., and a mixture of acrolein and water is distilled off; (2) b -methylglycerol is heated in a pressure still to 120 DEG  C. with aqueous sulphuric acid yielding a -methylacrolein.  A sample has been furnished under Sect. 2 (5), of methyl isopropenyl ketone, obtained by treating 2 - methyl-1 : 2 : 3 - trihydroxy - butane with aqueous sulphuric acid at 100 DEG  C.  b -Methylglycerol is obtainable by treating symm.-dichloro-tert.-butyl alcohol with lime slurry to form b -methylepichlorhydrin, hydrating this to b -methylglycerol monochlorhydrin by means of dilute sulphuric acid, treating this product with dilute caustic soda to form b -methylglycidol and hydrating this by means of dilute sulphuric acid. a -Phenyl-b -methylglycerol is similarly obtainable from the phenyl derivative of dichlorotert.-butyl alcohol, obtainable by reacting isobutenyl chloride with phenyl magnesium bromide to form phenylisobutenyl, chlorinating this and reacting the product with hypochlorous acid.  b -(Hydroxymethyl)-glycerol is obtainable by treating g -g <1>-dichlorisobutene with hypochlorous acid to form trichloro-tert. butyl alcohol, converting this, by steps similar to those used in the preparation of b -methylglycerol, into b -(chloromethyl)-glycerol, and hydrolysing this with dilute caustic soda solution.