2693.     PICHLER, H., ZIESECKE, K. H., AND TRAEGER, B.  [Oxygenated Compounds, Particularly Alcohols, From Isosynthesis.]  Brennstoff-Chem., vol. 31, 1950, pp. 361-374.

Purpose of this work was to investigate the oxygenated compounds formed on isosynthesis catalysts and to establish how their composition depends upon the various catalyst additions, the synthesis temperature, and the pressure.  In preparing the products, the synthesis conditions were, in part, intentionally chosen so that fewer hydrocarbons and more oxygenated compounds would be formed.  In order to investigate the synthesis products, which were obtained through distillation, it was necessary to separate the oxygenated compounds from the hydrocarbons.  This was first attempted by selective solution, but it did not succeed. It was necessary to convert the alcohols into their boric acid and phthalic acid esters, which were then easily separated from the hydrocarbons.  The most suitable way to isolate the alcohols boiling up to 160° from the isosynthesis mixture was to separate the nonalcohols through azeotropic distillation with MeOH.  The alcohols isolated in this way were fractionally distilled afterwards and characterized on the basis of their physical properties.  Aldehydes and ketones, as well as acids and esters, have been determined by their chemical characteristics.  The dehydration necessary for precise characterization of alcohols can be well-accomplished by extractive distillation with carbon tetrachloride.  The composition of the isosynthesis products shows, that under the reaction conditions by which oxygenated compounds are formed, the alcohols are of the same type as those formed on oxide catalysts in the synthesis of MeOH and higher alcohols.  MeOH and isobutanol were found as the chief components besides small amounts of ethanol and propanol as well as traces of isopropanol and tertiary butanol.  The higher alcohols investigated (up to C₇) showed almost exclusively a-branchings.  The carbonyl compounds formed in relatively small amounts consisted especially of isobutyraldehyde.  The ester fraction was very small.  The acid content made up about half of the ester fraction, and isobutyric acid was the chief acid component.  Addition of alkali favored up to a certain extent the formation of higher alcohols.  ZnO added to the ThO₂ catalyst increased the higher alcohol content.  Addition of Al₂O₃ strongly reduced the formation of alcohols at far lower synthesis temperatures than normal, apparently through dehydration, and ethers, in part, appeared as byproducts.  An increase in pressure effected an increase in the amount of alcohols, probably because of the prevention of dehydration.  Hereby, somewhat greater amounts of alcohols, usually present only in traces, have been formed.  Increase in temperature favored dehydration, in fact, the straight-chain alcohols decreased in amount less than the secondary or even the tertiary alcohols.  The amount decreased further with decreasing C number.  A flow diagram is presented that explains the formation of the oxygenated compounds in the catalytic hydrogenation of CO.  A comparison of the oxygenated compounds and the hydrocarbons from isosynthesis makes it appear that alcohols are the probable primary products from which by dehydration and hydrogenation the corresponding aliphatic hydrocarbons are formed.