DE840844C - Process for the preparation of a mixture of isomeric cyclic ethers - Google Patents

Description

Process for the preparation of a mixture of isomeric cyclic ethers Los is known that 1, f-13utvlen ;; lycole under the f: action of dehydrating catalysts increased temperatures in almost quantitative prey converted into the corresponding tetrahydrofurans be converted, \%, although it does not matter whether one liquid or solid dehydrating catalysts used. 1? S is also known to help treat of hexancliol-i, 6 finite about 57 ° sulfuric acid at elevated temperatures a mixture of isomers cyclic ethers of the common formula C ,; H120 received, the about @ o °; a 1, .l-Ätlier, about 38,5 °, / r, 1, 5 -ether and contains only very small amounts of hexamethylene oxide.

It has now been found that a mixture of isomeric cyclic Ethers of the formula C; Hl., O, which contains considerable amounts of hexamethylene oxide, produce can, if one hexanediol-i, 6 at temperatures between Zoo and 300 ° of the action solid dehydrating catalysts subjected.

Suitable dehydrating catalysts are, for. B. the oxides of Aluminum, thorium, titanium and zirconium, and also bauxite, the phosphates and borates of aluminum, zinc or cadmium and silica gel. You can alone or in a mixture with one another or with activators, such as free acids, and optionally arranged on carriers can be used.

The best temperatures are between 230 and 24C) '.

You can work batchwise or continuously. In the latter Trap the hexanediol, 6 expediently in the stream of an inert gas, such as nitrogen or hydrogen, or with the addition of a liquid diluent, like water, trickling over the catalyst, which is firmly arranged in an oven.

The product obtained in almost quantitative yield consists of essentially from 2 ethyl tetra-15-drofuran, 2-methyl tetrahydropyran and hexainetlivIenoxyd. The proportions change depending on the temperatures and reaction conditions used. The mixture can be broken down into the individual isoers by fractional distillation Disassemble ether.

Both the mixture as such and the individual ethers excellent solvents; they are also valuable intermediates for chemical Implementations.

Compared to the already mentioned known process for splitting off water from hexanediol-i.6 with 570% sulfuric acid, the present process has the advantage that solid catalysts are more convenient to handle and can be reused in a simple manner without losses, whereas this is the case for 57% sulfuric acid does not apply. Above all, however, the present process also permits the recovery of the hexamethylene oxide in considerable quantities, which is formed in very small quantities in the known process. Example 155 g of 1.6-hexanediol per liter of catalyst are allowed to trickle through a tube filled with granular active alumina at 230 ° in a stream of nitrogen. A total of 365o g of condensate is obtained per liter of catalyst in the course of 24 hours. The aqueous layer (550 g) is separated off and the oily layer is worked up by fractional distillation with the aid of an effective column. This gives after a first run of about 30 g of diolefinic proportions 3109 2-methyltetrahydropyran (boiling point 1o3 °), 1240 g of 2 ethyltetrahydrofuran (boiling point 106 ') and 1085 g of hexamethylene oxide (boiling point 121 °); About 450 g of higher-boiling components remain as a residue.

Claims (1)

PATENT CLAIM: Process for the preparation of a mixture of isomeric cyclic ethers of the composition C, H12 O by catalytic dehydration from hexanediol-i, 6 at elevated temperature, characterized in that hexanediol-i, 6 at temperatures between 200 and 300 ° of the action of solid dehydrating agents Subjects to catalysts.