DE930387C - Process for the preparation of trimethylol compounds with at least 5 carbon atoms - Google Patents

Description

Process for the preparation of trimethylol compounds with at least 5 carbon atoms It is already known for the production of trimethylol compounds with at least 5 carbon atoms, such as. B. methyl trimethylol methane, ethyl trimethylol methane or propyl-trimethylol-methane, aldehydes with at least 3 carbon atoms, such as propionaldehyde or butyraldehyde, together with advantageously 3 mol of formaldehyde in an aqueous medium to condense alkaline, with the proviso that this temperature of o to q.0 °, advantageously up to 25 °. After the reaction has ended, you can proceed in such a way that the alkaline condensing agent is in the reaction product is removed at most so far that the formic acid formed in the reaction remains essentially bound. It has now surprisingly been found that the condensation can also be carried out with particular advantage while maintaining temperatures can make below o °, for example at between -5 and - zo ° Temperatures.

You can proceed in such a way that you use a higher aldehyde with at least 3 carbon atoms, e.g. B. butyraldehyde, in the course of a few hours in such Sub-zero temperatures condensed with formaldehyde by For example, the former can run into an alkaline formaldehyde solution or gradually adding in small amounts. A slight increase in the Temperature nothing unless one by appropriate Prevents measures that .the, zero point is exceeded. It is advisable to stir the reaction mixture during the inflow. The stirring can also be continued for a certain time after the end of the process Continue adding the higher aldehyde. This can then be considered proportionately Then briefly heat the reaction mixture to temperatures of up to about 60 °. It is also expedient to give the condensation after the end of the condensation on the occasion of heating used to remove or dull the alkaline condensing agent Acid too.

This process gives methyl, ethyl, propyl, etc. trimethylol methane with high yield. and good purity.

The process is explained below using two examples.

Example i To carry out the condensation, 1172 g of a 30% formaldehyde solution and 1500 g of water are initially introduced. At a temperature of -5 °, 930 g of a 24.4% propionaldehyde solution are then run in over 3 hours and 150 g of hydrated lime are added in portions. After the end of the run-in, stirring is continued for 10 minutes at -5 ° and then heated to 56 °, at which temperature just before the point of transition - the pH is adjusted to 6.5 with 50% sulfuric acid. After filtering off the calcium sulfate, it is evaporated to dryness in vacuo. The resulting crude product is obtained in an amount of 570 g and is pure white and very firm.

The recrystallization takes place in twice the amount of acetone -j- 3 ° / o methanol + 1 0 /, activated charcoal in such a way that after boiling for 20 minutes on the reflux condenser and filtering off the ash, the filtrate evaporated to half and the pure methyltrimethylolmethane is allowed to crystallize. A second crystallization of leg product is obtained from the mother liquor by repeated evaporation and crystallization.

The product, washed with cold acetone and dried, weighs 377 g, corresponding to 80.1% yield. The evaporated residual liquor. result in .one Vacuum distillation (3 mm Hg column) a further 9.4 g, so that a total of 386.4 g of the - Product are obtained, which corresponds to a yield of 82.1%. Melting point 192 to 197 °, ash 0.35%, acid 0.040%. Example 2 176o g of 30% are obtained Formaldehyde solution and 22oo g of water and cooled down to - 10 °. 1500 g of a 22.7% propionaldehyde solution and 225 g of hydrated lime are now added in such a way that that the heat of reaction a gradual rise in temperature to - i ° to Causes the end of the enema. This takes 4 hours. After completion the enema is immediately heated up to 60 ° and at this temperature, just before the envelope with 50% sulfuric acid, neutralized (pg = 7). After separation the resulting plaster is concentrated in a vacuum until no more water passes over: This results in a large amount of colorless, solid rolled product.

This crude product is boiled in a reflux condenser for 1/2 hour with 180 g of acetone -f- 72 g of methanol -f- io g of activated charcoal. -The hot solution is filtered off from the remaining ash and allowed to crystallize after concentration to half. This and another crystallizate obtained after repeated evaporation of the mother liquor gives 563 g of pure product after washing with cold acetone, corresponding to a yield of 79.9%.

A further 22 g of pure product are obtained by distilling the residual liquor, so that a total of 585 g are obtained, which corresponds to a yield of 83.00%. Melting point 193 to igg °, ash 0.400 /, acid o, o ° / o. -

Claims (1)

Claim: Process for the preparation of trimethylol compounds with at least 5 carbon atoms by alkaline condensation of aldehydes with at least 3 carbon atoms with advantageously 3 mol of formaldehyde in an aqueous medium at temperatures below 40 °, characterized in that the alkaline condensation while maintaining temperatures below 0 °, expediently from -5 to - 10 °, whereupon expedient. the condensation is completed by a relatively brief heating of the reaction mixture to temperatures of up to about 60 ° and, if necessary, the acid used to remove or blunt the alkaline condensation agent after the condensation has ended is then added immediately at this temperature.