SU516690A1 - The method of purification of the reaction mass of the synthesis of 4,4-dimethyldioxane-1,3 - Google Patents

Description

one

The invention relates to a process for the purification of the reaction mass of the synthesis of 4,4-dimethyldioxane-1,3 (DMD).

In the existing production of DMD-synthesis from isobutylene and formaldehyde from the DMD synthesis reactor, the so-called shty oil is supplied for further non-processing, the following composition, wt.%: Fraction C (isobutylene-1 isobutane; 45-5 O Trimethylcarbinol (TA1K; cJ - t Dimetsch1dioksan40-45

High boiling point by-products (runway) 4-5

Water1-2

Formaldehyde 0.5-1

During the subsequent processing of the oil layer, formaldehyde contained in it at elevated temperatures forms with the components of the oil layer tar-like products that can clog pipelines and equipment. As a result, the unproductive losses of foomaldehyde sharply increase, which, in turn, increases the coil / loss of the target product. Thus, for further processing of the oil layer from bliss, it is necessary to isolate formaldehyde.

A known method of purification of the reaction mass of the synthesis of DMD containing TMK from formaldehyde with the use of azeotrophy rectification. Hydrocarbons, such as hexane or benzene, are used as the separating agent.

The disadvantage of this method is the need to create an additional technological separation agent separation agent, which complicates the process,

In order to simplify the process, a rectification process has been proposed, with the presence of 5-20% by weight of water.

Claims (1)

Formaldehyde is distilled off with TMK and DMD water azeogrones (i.e., those that are located in the oil layer of DMD synthesis). The amount of water in the azeotrope with TMK is 11.8 Bes.%, And with a gas content of 35.2 wt.%. The rectification is carried out at a pressure of 3-5 atm. From the top of the column, TMK and D.ASH wave azeotropes are combined with formaldehyde at 70-90 ° C, depending on the pressure in the column, and from the bottom of the column at 14O-160 C - DMD with high by-products and excess water. This mixture is exfoliated and water is reused. The added water maintains the temperature in the cube of the column in the range of 140–160 ° C. QB lack of water (temperature is about 200 ° C), which reduces the thermal decomposition of the components of the synthesis and makes it possible to isolate up to 97% by weight of formaldehyde. PRI me R. The continuous distillation column5, operating under a pressure of 4.5 atm, is supplied with an oil layer of DMD synthesis and water in the following amounts (in g / hour): Fraction C 1000 TMK80 DMD675 High-boiling by-products80 Water 150 Formaldehyde 15 Total: 2000 From the top of the column at 85 ° C, taken (in g / hour): Fractions of C 1QOO. 80 Traces of TV 14.5 Formaldehyde 1112.5 "From the bottom of the column they are beaten at 148 C (in g / hour): DMDg High boiling by-products 80 products Formaldehyde Total: The oil layer removed from the cube is practically non-formaldehyde (0 , 03 - 0.05 wt.%). Extraction of formaldehyde 97 weight%. DETAILED DESCRIPTION OF THE INVENTION The method of purification of the reaction mass of synase 4,4-dimethyldioxane-1,3 from formaldehyde using azeotropic rectification, which, in order to simplify the process,. The process of ektifikatsii lead in the presence of 5-20.% water.