DE832291C - Process for the preparation of ª † -oxybutyraldehyde - Google Patents

Description

Process for the production of y-oxybutyraldehyde It is already known To dehydrate 1,4-butanediol by heating in the presence of catalysts. the dehydrogenation catalysts previously used for this purpose, preferably copper, certain Metals of the B. group and oxidic catalysts lead the reaction in such a way that butyrolactone is the major dehydrogenation product, while that at a lower level of oxidation standing y-oxybutyraldellyd not formed or only in a very minor amount will. Since;, - Oxyl> utyraldehvd and butvrolactone, moreover, do not separate very easily let, were the previously known dehydrogenation methods for 1, 4-butanediol for 1-l production of this aldehyde hardly usable.

It has now been found that the dehydrogenation of 1, 4-butanediol one takes a different course and the product preferably obtained is;, - oxyl> utyraldehyde, when using cobalt catalysts, especially those whose catalytically active part consists predominantly of cobalt, is used. Metallic cobalt can be used as such, optionally use on supports such as silica gel; supported catalysts are particularly suitable, by soaking with a cobalt salt solution, e.g. B. Cobalt Nitrate, and Reduction were produced at temperatures below 20o °. By other metals, e.g. B. copper, the cobalt can still be activated. Reduced synthetic ones have proven to be excellent Tried and tested cobalt copper spinels, which provide almost butyrolactone-free γ-oxybutyraldehyde. Dehydration is easiest at ordinary pressure or in an indifferent one Atmosphere, such as in the presence of nitrogen or hydrogen, in general Temperatures executed between 15o and 300 °. Appropriately chooses the temperature is between 19o and 2300. 1) 1e best yields are obtained if anhydrous or low-water butanediol, preferably less than 5% water, is used used and the throughput selected so that no more than about half, better not over 40% are implemented.

The γ-oxyl> utyraldehyde formed can be driven off from the unused butanediol by distillation. The remaining butanediol can be fed back into the reaction. 'You can also dilute the reaction mixture with the same amount of water and extract it with organic solvents, such as. B. ether, isolate the aldehyde or drive off the y-oxybutyraldehyde with steam, whereby a very pure product is obtained. EXAMPLE i 60 cubic meters of pure 1,4-butanediol are passed hourly through a tube 0.85 m long and 30 mm in diameter, which is charged with 750 cm3 of a cobalt catalyst (Co content 200/0) applied to Kies21ge1 at 195 '. The reaction mixture withdrawn from the tube contains 28% γ-oxybutyraldehyde and 0.5% butyrolactone, the remainder being butanediol. A single distillation gives an 80% γ-oxyl>utyraldehyde; it can be further concentrated duroli a second distillation.

If all other things being equal are used at i gor one off Cobalt and copper on silica gel (20% Co, 1% Cu) existing at 17o ° in weak Hydrogen flow reduced catalyst, 33 to 35% of the 13ttanediol is transformed into y-oxy ~ butyraldelivd. The 13titvrolactc »i content of the product is o, 80/0. 13eisl) iel 2 About 75o cm3 of an atis cobalt copper spinel existing on silica gel Catalyst (16.2% Co, 8.8% Cu), which was reduced at 40o ° in a hydrogen stream, one passes hourly at 225 ° 6o cin3 pure i, 4-butanediol in a mixture with nitrogen. 40% of the 1,4-butanediol is converted into γ-oxyliutyraldehyde. plan drives out the y-oxybutyral (leliyd is removed from the reaction product with water vapor, and the condensate is etherified out and distilled. The butyrolactone content of the γ-oxyl) utyraldehyde obtained in this way is only 0.2%.

You work with a cobalt copper spinel under otherwise identical conditions (64.8% Co, 352% Cu) without carrier, which deforms into strands of 4 X 6 mm and at 40o ° has been reduced in the weak stream of hydrogen, at 23o °, so will also 40% of the butanediol converted to y-oxybutyraldehyde. The reprocessed aldehyde contains only 0.3% butyrolactone.

Claims (1)

PATr \ TA'N5t'ßC'CIl: Process for the production of y-Oxy1) utycaldehyde, characterized in that 1, 4-butanediol using cobalt catalysts catalytically dehydrated.