SU1199755A1 - Method of producing 4,4-dimethyl-1,3-dioxane - Google Patents

Abstract

METHOD OF OBTAINING 4,4-DIMETHYL-1, 3-DIOKSANA by the interaction of formaldehyde with isobutylene at 80100 C and a pressure of 1.5-2.5 MPa in the presence of an acid catalyst with the subsequent separation of the reaction mixture into oil and water layers, by evaporation of the aqueous layer at 45-90 ° C and a pressure of 0.003-0.052 MPa, by recycling the evaporated water layer to the synthesis stage in a mixture with a solution of fresh formaldehyde, due to the fact that, in order to increase the process performance, reduce losses of formaldehyde and reduce corrosion of the equipment, uparku water layer carried out in two stages, in the first stage the water layer is evaporated by 35-70%, the cubic product of the first stage of the evaporated water layer is mixed with a fresh formaldehyde solution, taken in a concentration of 38-45%, to achieve a formaldehyde concentration in the mixture equal to 23-32,0%, and (L luchennuyu mixture is served on the second stage of evaporation.

Description

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The invention relates to an improved process for the preparation of 4,44 methyl-1, 3-dioxane (DHS), which is an intermediate product in the production of isoprene, from formaldehyde and isobutylene. The aim of the invention is to intensify the process, reduce formaldehyde and reduce the corrosion of equipment: U, p and measure 1 (according to a known method). / 59.2t / h of a formaldehyde solution in a mixture with organic compounds (for foraldehyde mixture) recirculated in the process, wt.% Formalde guide 32.4 Methanol. 0.9 Trimethyl carbinol (TMK). 0.2 Dimethyldioxane (DVD) 0.8 VPP16.4 Oxalic acid 2.47 Formic acid 0.2 Water The rest is fed to the reactor block for the synthesis of DM 40.3 t / h of a direct fraction of isobutane from the fraction with a concentration of isobylene of 49.5 wt. The% is fed to an extractor for extracting organic components from the distillate and for the evaporation of the aqueous layer of the reaction mixture for the synthesis of DVD. The amount of distillate at the inlet to the extractor is 44.9 t / h, the composition of the distillate is indicated below. From the extractor, 30.3 tons of extracted distillate, which is sent to the recovery column of formaldehyde, and 54.9 tons / h from the butane-isobutylene fraction, wt.%, Are extracted: H-Butane, 0.3 Isobutane, 36.7 Isobutylene, 36.3 Alpha-, beta-butylenes 0.3 Formaldehyde0.7 DVD19.2 Unsaturated alcohols and methylal0.1 Trimethylcarbinol (TMK) 3.3 VPP3.1 The isobutane-isobutylene fraction with the extracted organic components is fed to the reactor block for the synthesis of DMD. The synthesis of DMD in the reactor block is carried out at 97.4 C and a pressure of 25 a, 5 MPa), the contact time of the raw material is 3 hours. A reactive mixture is withdrawn from the reactor block, which is divided into oil and water layers. 60.4 t / h of aqueous layer are obtained, wt.%: Formaldehyde Methanol DSh10,3 Oxalic acid Formic acid The rest is 53.8 t / h of oil layer composition, s.%: N-Butane, 0.3, Isobutane 33.0 Isobutylene 5.0 Alpha-, beta-butylenes 0.3 Formaldehyde. 1.3 DMC39.3 Unsaturated alcohols and methylal 0.3 TMK 10.7 VPP..5.2 Oxalic acid 0.4 Water: 4.2 The oil layer is washed with a sieve of formaldehyde and oxalic acid. Obtain 7.2 t / h wash water composition, wt.%: Formaldehyde 8,7 Methanol. .0.9 TMK .2.8 DMD8.4 VPP16.2 Oxalic acid 0.8 Water Others Wash water is mixed with water. The total amount of 67.6 t / h aqueous concentration of formaldehyde wt.% Is fed into the column of the evaporated layer, operating at a residual pressure of 0.5 at (0.05 MPa) in the bottom part of 80 ° С. camping evaporated at 66.5%. Of the cubic parts of the column, 22.7 t / h of the aqueous Aqueous layer of the composition,%, are derived: Formaldehyde8.3 Methanol0.3 TZh0.4 DVD2.3 VPP41.3 Oxalic acid 6.4

3

Formic acid 0.5 Water Else

One stripped off water layer is sent to the reactor block for the synthesis of alkaline phosphorus for mixing with the bottom liquid of the column the concentration of fresh formaldehyde solution.

45.0 t / h of distillate of composition, wt.%, Are taken from the upper part of the water column;

Formaldehyde 4,4

Methanol

TMK6.3

dad15,0

VSh0,3

Oxalic acid 0.03 Formic acid 0.04 WaterEstal

The distillate of the aqueous layer is sent to an extractor to extract the organic components of the direct isobutane-isobutylene fraction from it. 54.9 t / h of isobutane-isobutylene fraction are obtained, which is sent to the synthesis reactor unit, and 30.3 t / h of extracted distillate, and the composition is prepared by weight, wt%:

. Formaldehyde6,5

Methanol2,1

TMK1,2

Runway0,2

Oxalic acid 0.03 Formic acid 0.04 Water Else Extracted distillate is mixed with 87.2 t / h of a 6.6% reversible formaldehyde solution, coming from the decomposition plant of the oil generator to isoprene, and also with 11.9 t / h a distillation column for the concentration of a fresh formaldehyde solution (the composition is given below) and sent to a formaldehyde recovery column under pressure.

48.5 t / h of a fresh formaldehyde solution with a formaldehyde concentration of 41.6% and methanol of 2.1% are fed from a formalin de-moistening column to a concentration column of a fresh formaldehyde solution operating under a residual pressure of 0.05-0.15 at. (5-15 μPa), at a temperature in the bottom part of 55-55C. From the concentration column, 86.5 t / h of bottom liquid is withdrawn, wt.%: Formaldehyde 50.7

Methanol1 5

WaterEverything

97554

The bottom liquid of the concentration column of the fresh formaldehyde solution is mixed with 22.7 t / h of the evaporated aqueous layer and 59.2 t / h 5 of the formaldehyde mixture (composition indicated at the beginning of the example) is obtained, which is sent to the DMD synthesis reactor block.

From the upper part of the concentration column, 11.9 t / h of distillate of composition are taken, wt%:

Formaldehyde13,7

Methanol 4,3 Water Else

Distillation concentrate columns (5 neither fresh formaldehyde solution mixed with an extracted distillate of an aqueous layer column and a return formaldehyde solution from the DMD decomposition shop serve 20 S formaldehyde recovery column under pressure. The composition of the column, wt.%:

Formaldehyde7,2

Methanol0.9

25 TMK0.2

DMD0,1

Runway0,1

Oxalic acid 0.01 A formic acid 0.05 3Q Water Else

The amount of the mixture is 129.5 t / h. The total amount of 100% formaldehyde in the distillation column of the aqueous layer evaporation and concentration of the formaldehyde solution is 3.6 t / h, the amount of return formaldehyde from the decomposition plant DMC is 5.76 t / h.

The formaldehyde recovery column operates under a pressure of 5-6 atm (0.50, 6 MPa), the temperature in the bottom part is 150-160 s. Get 26.9 t / h distillate composition, wt.%:

Formaldehyde 34,5

Methanol4.0

 TMK0.9

DMD0.4

Runway. 0.4

Formic acid 0.14 Water - Remaining 50 Distillate is sent to a formalin degummeting column to produce fresh formaldehyde.

The bottom liquid of the recovery column in the amount of 10.2 tonnes per hour is directed to the treatment plant. Bottom liquid composition, wt.%: Formaldehyde 0.09 Formic acid 0.05 VGSH0.05 WaterOther Estimated Formaldehyde losses in the formaldehyde recovery column are 374 kg / h or 17.0 kg in terms of 1 ton of production DMD Recovery time equipment for the recovery column is 3000 hours. The washed oil layer is rectified to obtain 16.5 tons / h of the return C4 fraction, 7.0 tons / h of the recycled fraction of TMK and 27.5 tons / h of the target fraction. From the target fraction of the oil layer, 22.8 tons / h of DMD and 4.72 tons / h of runway were added. The output of the DSB is 54.8 tons per day. The runway yield is 207 kg / ton DMD. Example2. 59.2 g / h of formaldehyde charge composition, wt.%: Formaldehyde Methanol Oxalic acid Formic acid The rest is fed to the reactor unit for the synthesis of DMD. 41.6 t / h of the direct isobutane-isobutylene fraction with a concentration of 30 isobutylene and 49.5 wt.% Are fed to an extractor to extract organic components from the distillate of the stripped water column of the reaction mixture for the synthesis of DMD. The amount of distillate 35 liters at the inlet to the extractor is 45.5 t / h, the composition of the distillate is given below. 30.9 t / h of the extracted distillate, which is sent to the formaldehyde recovery column, and 55.1 t / h of the isobutane-isobutylene fraction-composition, wt.%: -C-Butane; 0.3 Isobutane 37 , 45 Isobutylene36.1 Alpha, beta-butylenes 0.2 Formaldehyde1.1 DMD18.8 Unsaturated alcohols50 and methylal0.1 TMK3.1 VPP3.2 The isobutane-isobutylene fraction with 55 organic components extracted is fed to the reaction block of DOD synthesis. The synthesis of DMD is carried out at a pressure of 25 at (2.5 MPa) 1199755 and qi of 5 liters during 10 15 and mai boilers at 6, in the Up 44 slst 48 pa to 6, and the raw material contact mixture From the reactor block The reaction mixture is withdrawn, which is divided into water and oil layers. Get 60.0 t / h st layer composition, wt.%: Formaldehyde 5,3 Methanol .1,2 TMK, 4.8 TsShch99 VPP14,1 Oxalic acid 2.2 Formic acid acid 0.2 WaterOtherly 4.4 t / h of oil layer of composition, sec.%: n-butane Isobutane Isobutylene Alpha, beta-butylenes Formaldehyde Unsaturated alcohols and methylal 0.3 TMK10.4 VPP5.7 Oxalic acid 0.4 Water 3.7 The oil layer is washed intelligently Doy from formaldehyde and sorrel slots. Obtain 7.5 t / h washdown composition, wt.%: Formaldehyde 8.9 Methanol 0.8 TMK3.1 grandfather. 7.9 VPP15.7 Oxalic acid 0.7 Water Vital Aqueous layer mixed with washing water in a total amount of 67.4 t / h with a formaldehyde concentration of 0 wt.% Served in an evaporated column of the bottom layer under the conditions of example 1. Arch wire t by 66.5%. 7 t / h of distillate and 22.7 t / h with a cube of liquid (one stripped of water o) are obtained with the compositions according to Example 1. 22.7 tons / h of the aqueous layer evaporated in the first upund are mixed, 5 tons / h of fresh formaldehyde assembly composition according to example 1 and shine a mixture of composition, wt.%: Formaldehyde31.0 Methanol1.5 TZh0,1 DMD. 0.7 VPP13.2 711 Oxalic acid 2.0 Formic acid 0.1 Water The remaining 71.2 t / h of the mixture is fed to the second stage of evaporation in a column operating at a residual pressure of 0.2 at (20 MPa) and a temperature in the bottom Part 65 C. From the bottom of the column, 59.2 t / h of the bottom liquid is taken, which is used directly as a formaldehyde charge, and 11.9 t / h of distillate composition, May. %: 6.5 Formaldehyde 4.3 Methanol 0.1 0.5 0.2 0.2 0.04 Formic acid Else Water 11.9 ton / h of distillate are mixed with 44.7 ton / h of distilled water and fed to the formaldehyde recovery column. The total amount of 100% formaldehyde in the distillate mixture is 2.15 t 1h. Here, 87.2 t / h of a 6.6% recycled formaldehyde solution coming from the DMD decomposition plant into isoprene are served. The amount of 100% formaldehyde in the return formalin is 5.76 t / h. The formaldehyde recovery column operates under the conditions of example 1. From the upper part of the column, 26.9 t / h of distillate with the composition according to example 1 and 116.9 t / h of the bottom water liquid, wt.%: Formaldehyde 0.08 Formic acid 0 , 04 Runway 0.04 Water Remaining Formaldehyde losses in the formaldehyde recovery column are 347 kg / h or 15.2 kg per 1 ton of production DMD. The overhaul mileage of the recovery column equipment was 6000 hours. 23.58 t / h of DND and 4.88 t / h of HS1 are separated from the oil layer. The production of DMD is 566 tons per day, the runway yield is 207 kg / ton DMD. The DMD rate is increased by 3.3% compared to its production by a known method described in Example 1. 99755 de 5 10 IO Code 15 and next 20 cm long with cm 25 30 cm re pho about co 55 re 38 to 8 trymid. 59.2 t / h of a formalgid charge of the composition in wt.%: Formaldehyde 40.4, Methanol 0.6 TMK0.1 DMC0.8 VPP15.7 Phosphoric acid 2.4 Formic acid 0.2 Water Vkalnaya give into the reactor block synthesis D1. The amount of direct isobutane-isobulene fraction is 46.8 t / h, the isobutylene concentration is 49.5%. Synthesis of dschp was carried out at 25 at (2.5 mPa), and water evaporation was carried out at 66.5% under conditions of immersion 1. 22 , 3 t / h of fresh formaldehyde with the composition according to example 1 and get the composition, wt.%: Formaldehyde 31.4 Methanol 1.6 TMK0.1 DMD0.6 VPP11.7 Phosphoric acid 1.8 Formic acid O, 1 80.0 t / h of the mixture of this composition is given into the second-stage upar column operating under the conditions of example 1. 52.2 t / h of bottom vial liquid are obtained, the torus is used directly as a formaldehyde mixture (combined is given at the beginning of the example), 20.4 t / h of distillate composition, sec.%: Formaldehyde 8.0 Methanol4.3 TMK0.1 DMC-0.4 VPP0.2 Formic acid 0.04 WaterOther Distillate of the column is fed to the column Forderation of Fordehyde. The total amount of 100% rmaldehyde in the distillates of columns in their water vaporization stages is 3.60 t / h. The formaldehyde loss in the formaldehyde coupe column is 7 kg / h or 14.5 kg per ton DOD. The DMD output is 640 g per day, the VSH1 yield is 209 kg / t dach. The overhaul mileage of the recovery column equipment is 5500. The DMD output is increased by 16.8% compared to its production by the known method described in Example 1. P r m a p 4. 59.2 t / h of the formaldehyde charge composition, wt. %: Formaldehyde 39.0 Methanol1.5 TJ0.2 DVD0.8 Runway 15.6 Hydroxyethylidene diphosphoric acid2.4 Formic acid O, T Water The remaining is fed to the reactor block of the synthesis of DMD The amount of isobutane-isobutylene fraction is 45.6 t / h, isobutylene: 49.5%. The synthesis of DMD was carried out under conditions of example 2. The water layer was evaporated by 50%, the bottom of the first stage of the evaporation column was 75 ° C, and the residual pressure was 0.4 atm (0.04 MPa). 33.9 t / h of distillate composition, wt.% Are taken from the top of the column: Formaldehyde4.4 Methanol1.5 TZH6.7 DMD15.4 VPP -0.3 Hydroxyethylidene diphosphoric cylot Absence Formic acid 0.04 Water OTHER Distillate of the column is directed to the extractor to extract organic components from it, and then sent (in the amount of 25.9 t / h) to the formaldehyde recovery column. 33.9 t / h of the evaporated water layer of the composition, wt.%, are removed from the bottom of the column: 0 Methanol 0,6 TMK1,9 tsch6,0 VSh127,8 Oxyethyl lidene diphosphoric acid 4,2 Mzfavina acid 0,3 Water Stayed The evaporated aqueous layer is mixed with 55.6 t / h of fresh formaldehyde solution with the composition of Example 1-5 and obtain 89.5 t / h of the mixture of the composition. wt.%: Formaldehyde Methanol Hydroxyethylidene Diphosphoric Acid 1.5 Formic Acid 0.1 Water. The rest of the mixture is fed to the column of the second stage of evaporation, operating under a residual pressure of 0.3 at (0.03 MPa) at a temperature in the bottom part of 70 C. Selection 59.2 t / h of the bottom liquid, which is used directly as a formaldehyde mixture (composition The charge is given at the beginning of the example), and 30.2 t / h of distillate composition, wt.%: Formaldehyde Methanol Hydroxyethylidene diphosphonic acid Absence Formic acid 0.04 Water The rest is fed to the extraction by direct Cv fraction and then to the formaldehyde recovery column under pressure. The total amount of 100% formaldehyde in the distillates of both columns of the stripped aqueous layer is 3.60 t / h. The formaldehyde loss in the recovery column is 386 kg / h or 15.0 kg / ton DMD. The production of DMD is 620 tons per day, the output of the runway is 208 kg / ton DMD. Production of DMD is increased by 13.1% compared to working it by the known method described in Example 1. The overhaul of the equipment for the recovery column of the dehydro formal is 5700 h. P RIM e p. 59.2 t / h of the formaldehyde mixture of composition, wt. %: Formaldehyde36.2 Methanol1.4 TZh0.2 DVD0.8 VPP15.5 Oxalic acid2.4 Formic acid 0.1 Water The rest is fed to the reactor unit for the synthesis of DVD.

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The amount of isobutane-isobutylene fraction is 47.3 tons per hour, the concentration of isobutylene is 49.7%. Synthesis of HPC was carried out under conditions of example 1. The water layer was harvested by 35%, the bottom of the column of the first steaming stage was 73 C, the residual pressure was 0.533 atm (0.052 MPa).

From the first part of the column, 22.9 t / h of distillate composition, wt.%, Are taken: Formaldehyde 4,3

Methanol1,4

TMK7.1

D№ - 15,5

Runway 0.3

Oxalic acid Absence Of formic acid 0.03 Water Else

- The distillate of the column is sent to the extractor to extract the organic components from it, then sent (in the amount of 17.5 t / h) to the formaldehyde recovery column 42.5 t / h of the evaporated aqueous layer of the composition, wt. .%:

Formaldehyde 6,4

"Methanol0,6

TMK1, 8

DMD5,9

Runway28,3

Oxalic acid 4.3 Formic acid 0.3 WaterEstal

One stripped off aqueous layer is mixed with 49.3 t / h of fresh formaldehyde solution with the composition of Example 1 and a mixture of composition and wt.% Is obtained: 92.3 t / h;

25.4

id 1.5 0.8 2.1

:

10.4

1.6

acid

0.1 acid.

Rest

The mixture is fed to the column of the second stage of evaporation, operating under a residual pressure of 0.3 at (0.03 MPa) at a temperature of the bottom part of 70 ° C. 59.2 t / h of the bottom liquid is taken, which is used directly as a formaldehyde mixture (the composition of the mixture is given at the beginning of the example) and 33.1 t / h of distillate composition, wt%:

Formaldehyde7.9

Methanol1,5

9975512

TMK1,7

DVD4,8

Runway0.3.

Oxalic acid Absence 5 Formic acid 0.04 Water Else

The distillate of the column is sent to the extractor to extract the direct C-fraction of the organic components from it, then fed (in the amount of 28.4 t / h) to the formaldehyde recovery column under pressure.

The total amount of 100% formaldehyde in the distillates of both water vaporization columns is 3.6 t / h. The formaldehyde loss in the recovery column is 385 kg / h or 16.6 kg / ton of production DMC, i.e. they are 2.3% less compared to 20 with the known method described in Example 1.

The output of the drill rig is 555 tons / day, the output of the runway is 210 kg / t DVD. Developed by DOD is 1.3% more compared to 25 with its output given in Example 1. The overhaul mileage of the equipment for the formaldehyde recovery column is 3500 hours.

PRI me R 6. 59.2 t / h for a formal 30 dehydrous charge composition, wt.%:

35.2

Formaldehyde

1L

Methanol

0.2

TJ

0.8

dats

15.5

Runway

35

2.4

Oxalic acid

0.1

Formic acid

Rest

Water

served in the reactor unit for the synthesis of DVD. The amount of isobutane-isobutylene

The 0 fraction is 47.3 t / h, the isobutylene concentration is 49.7%. The synthesis of DVDs was carried out under the conditions of Example 1. The water layer was harvested at 70%, the temperature in the bottom of the column

5 of the first stage of evaporation 45 С, residual pressure 0.03 atm (0.033 MPa). From the upper part of the column, 50.0 t / h of distillate of composition are taken, wt.%: Formaldehyde .3.3

0

Methanol1,4

TMK7.1

DVD15,5

Runway0,3

Oxalic acid absent

5 Formic acid 0.03 Water Else

The distillate is sent to an extractor for recovery. organic components, and then (and the amount of 44.0 t / h) in the formaldehyde recovery column. From the bottom of the column, 20.0 t / h of the evaporated water layer of the composition, wt.%, Were removed: Formaldehyde 7.8 Methanol .0.6 TMK1.8 DVD5.9 VPP28.3 Oxalic acid 4.3 Formic acid 0.3 WaterOval Steamy The aqueous layer is mixed with 63 t / h of a fresh 38% formaldehyde solution with the composition of the remaining components of example 1 and 83 t / h of the mixture of composition, wt%, is obtained: Formaldehyde. , 24 Methanol1 4 TMK0.7 Dad2.0 VPP9.1 Oxalic acid1.5 Formic acid 0.03 WaterOstalal Mixture is fed to the column of the second evaporation stage, operating under a pressure of 0.03 atm (0.003 MPa) at a cube temperature of 45 ° С . 60 t / h of the bottom liquid is taken, which is used directly as a formaldehyde mixture (the composition of the mixture is given at the beginning of the example) and 23.0 t / h of distillate composition, wt.%: Formalde hydro4.2 Methanol1,4 TMK1,6 DMD4 , 8 VPP0,3 Oxalic acid None Formic acid 0.03 Water. The rest Distillate columns are sent to an extractor for extraction from it. Direct Sc.-fractions of organic components, then it is fed (in the amount of 20 t / h) into a formaldehyde recovery column under pressure. The total amount of 100% ph maldehyde in both types of distillates is 3.4 t / h. The formaldehyde loss in the recovery column is 20 kg / h or 16.0 kg / ton of production DMD, i.e. they are 2.6% less compared to the known method described in Example 1. 514 The production of DVDs was 570 tons / day. The overhaul mileage of the formaldehyde recovery column equipment is 5000 hours. Example7. The method is carried out under the conditions of example 6, except that the temperature in the bottom of the second stage of the parity column is equal, the pressure is 0.0533 atm (0.052 mPa). PRI me R 8. The method is carried out under the conditions of Example 2, except that the synthesis temperature of DMD in the reactor block is 80 ° C and the pressure is 1.5 MPa, the contact time of the raw mixture is 4.5 hours. em 565 tons / day. Example 9. The method is carried out under the conditions of example 2, except that the synthesis temperature of DMD in the reactor block, a pressure of 2.5 MPa and in the first stage the aqueous layer is evaporated by 30%. The production of DMD is 548 tons / day. The data of the examples are summarized in Tables 1 and 2. The aqueous layer is evaporated in the first stage at 35-70%. Since after the separation of the reaction liquid for the synthesis of DMD into oil and water layers, the water content in the aqueous layer is 70%, the evaporation by more than 70% does not make sense. It is also not economically feasible to conduct an evaporation of the aqueous layer and less than 35%, since in this case the proposed method will in its essence approach the option of evaporating the aqueous layer in one stage. The formaldehyde concentration in the fresh formaldehyde solution is 38-45%, mostly 41.6%. The technical and economic indicators of the synthesis process of the TsCH are significantly improved as the Formaldehyde concentrates by reducing the energy costs while reducing the amount of evaporated water. However, carrying out the process with a formaldehyde concentration above 45% is complicated due to the possibility of formaldehyde conversion to vapor form and equipment clogging. When the process is carried out under conditions where the formaldehyde concentration is below 38%, the energy costs of packaging water introduced into the process with formaldehyde sharply increase. The concentration of formaldehyde, stepping on the second step of the water layer evaporation, is 23-32%. This concentration determines the concentration of formaldehyde in the mixture entering the DMD synthesis process. Thus, with a formaldehyde concentration of 23% in the stream entering the water layer evaporation stage I, the formaldehyde concentration in the mixture will be 38%, and with an initial concentration of 32%, the final concentration in the mixture will be 45%. . 5 The volume of the distillate does not reach the value of the reduced distillate of the column. Thus, the proposed method allows increasing the productivity of the DMD synthesis plant by 15-17%, reducing formaldehyde losses by 1510% and reducing the corrosion of the plates and caps of the formaldehyde recovery column, increasing the equipment’s overhaul mileage from 3000 to 6000 hours. T "in it" 1

4.4 8.3

4.4 8.3

4.4 8.3

4.4. 7.0

32.4 Note 12345678910 echani. e. Flows of the technological scheme: a mixture of an aqueous layer with wash water; a column for the evaporation of the water layer of the first stage; a distillate of a first stage aqueous layer column; one stripped off the water layer; a mixture of a solution of fresh formaldehyde with one stripped off of the aqueous layer; a second-layer stripping column; a distillate of a second stage water column; the cubic liquid of the second layer water layer column; formaldehyde solution entering the installation; formaldehyde charge at the exit to the reactor unit (by a known method).

Claims (1)

METHOD FOR PRODUCING 4,4-DIMETHYL-1, Z-DIOXANE by reacting formaldehyde with isobutylene at 80 ° C and a pressure of 1.5-2.5 MPa in the presence of an acid catalyst, followed by separation of the reaction mixture into oil and water layers, evaporation of the aqueous layer at 45 -90 C and a pressure of 0.003-0.052 MPa, by recycling the stripped off water layer to the synthesis stage in a mixture with a solution of fresh formaldehyde, characterized in that, in order to increase the productivity of the process, reduce losses of formaldehyde and reduce corrosion of the equipment, the water layer is evaporated in two stages, and in the first stage, the aqueous layer is evaporated by 35-70%, the bottom product of the column of the first stage of evaporation of the aqueous layer is mixed with fresh formaldehyde solution, taken in a concentration of 38-45%, until the formaldehyde concentration in the mixture is equal to 23-32 , 0%, and the resulting mixture is fed to the second stage of evaporation.