DE524101C - Process for converting higher quality alcohols into lower quality ones - Google Patents

Description

Process for converting higher-quality alcohols into lower-value ones It is known that 'n @ -Acetylengl'ykole in the presence of platinum or palladium black reduce with hydrogen. This occurs when using palladium catalysts saturated hydrocarbons, but mostly when using platinum catalysts not regulary; Mixtures of saturated glycol and saturated alcohol.

It has now been found that you can generally obtain a good yield Higher alcohols can regularly receive lower alcohols, if the former in the presence of hydrogenation catalysts, e.g. B. copper, silver, zinc or nickel catalysts made by adding alkalis, alkaline earths or their Compounds or of elements of the 3rd to 7th group of the periodic table or the compounds of which are activated, reduced with a considerable excess of hydrogen. The activation of the catalysts is advantageously effected by the fact that the Representation of the catalysts the starting material 'oxides, such as. B. Cr., 03, S. i O @, Ti O., Wo 03, Zr O., Mo, O, Vo, 0, etc., as such or in the form of their compounds clogs.

A sufficient activity of the catalysts can also be achieved in this way be that one applies the catalysts in very finely divided form or they used distributed on suitable supports such as fibrous asbestos, etc. For example finely divided cobalt powder can be used as a catalyst, which is obtained by reduction from powdered cobalt carbonate.

One obtains in the manner indicated, for. B. from glycol ethyl alcohol, from glycerin easily and in good yield propylene glycol and n-propyl alcohol. Even Higher alcohols, such as erythritol, hexites, etc., can be converted into Transfer lower hydroxyls, and so the homologous alcohols, glycols, glycerols are obtained etc., which so far z. Sometimes either not at all or only in a cumbersome way were accessible. The hydrogenation can be carried out both in gaseous and in liquid form Execute states with or without the application of pressure.

Example ii 1 Glass beads are made into a paste with water and 130 g of powdered, dry copper chromate, obtained by reacting molecular amounts of copper nitrate and ammonium chromate; one places o, 4. g of 89% phosphoric acid and reduced in a stream of hydrogen at 25o to 26o °. A hydrogen stream containing about 1 to 1.5 percent by volume of glycerine vapor is passed over the contact mass produced in this way at a temperature of from zoo to 20 °, and the gases leaving the contact space are strongly cooled. A liquid is deposited here. which is fractionally distilled after the removal of the water formed. The implementation of the glycerine is almost complete. The distillate consists of i # 2-propylene glycol, which is obtained in a yield of up to 70 °) a, and propyl alcohol; unchanged glycerol is no longer contained in the reaction product, or hardly at all. Instead of a catalyst activated with chromium, a copper catalyst activated with potassium chromate can also be used with the same effect.

Example ? - A mixture of hydrogen and vaporous i # 3-butylene glycol, which contains less than 10 parts by volume (based on the hydrogen) i # 3-butylene glycol, is passed over a chromium-activated nickel catalyst at a temperature of over 100 ° at such a rate that the gas mixture in the contact space is renewed about 100 times per hour. The reaction gases are cooled and, after drying, the condensate is separated by fractional distillation. In addition to butyl alcohols, methyl ethyl ketone is formed; the latter can be converted into isobutyl alcohol by further reduction, which can be obtained in this way in good yield.

Example 3 If glycerol is treated with the addition of reduced, with Chromium activated cobalt as a catalyst with hydrogen under pressure is thus formed depending on the chosen reaction temperature, predominantly propylene glycol or propyl alcohol; in addition, propane can also be formed. At a temperature of 80 degrees and a zoo at and using the above catalyst can be, for. B. up to 5o % I # 2-propylene glycol win.

Instead of glycerine, you can also use other higher-value alcohols, z. B. hexitol, erythritol, sugars, carbohydrates and similar substances, the hydrogenation subject, the substances mentioned in the liquid phase, d. H. in this The case is expediently used in a concentrated aqueous solution. Example ¢ sorbitol is mixed with half its weight in water and this solution after addition of reduced nickel catalyst containing about 5 ° F, chromium oxide, with hydrogen so start at -oo ° and Zoo at treated until there is no more hydrogen uptake. The reaction product is separated by distillation, with water between go and ioo ° aqueous propyl alcohol and between i8o to igo0 i -a-propylene glycol transforms; in addition, higher-boiling fractions such. B. i # 3 propylene glycol. The glycol yield is relatively very good. What remains is a viscous one Residue from unaltered sorbitol in addition to its anhydride and high-boiling reduction products.

Cane sugar can be subjected to reduction in a similar way, where it is advisable to replace the water with a sugar that is the same in weight as the one used Amount of i2 ° Joigen boric acid solution is used to dissolve.

Claims (1)

PATRNTANSPRU CH Process for the transfer of higher-quality alcohols in lower-valent, characterized in that the higher-valent alcohols in the presence of hydrogenation catalysts by adding alkalis, alkaline earths or their compounds or of elements of the 3rd to 7th group of the periodic System or its compounds are activated, with hydrogen in significant excess reduced.