The method of simultaneous receipt of pentaerythritol and sodium formate

 

(57) Abstract:

The invention relates to a method for the simultaneous receipt of pentaerythritol and sodium formate used in the chemical, leather and paint and other industries. The method includes the interaction of acetaldehyde with an excess of formaldehyde in the presence of sodium hydroxide and boric acid or borax to the complete transformation of the original aldehyde in a molar ratio of acetaldehyde: formaldehyde: sodium hydroxide: boric acid or borax=1: 6-8: 1,95-2,55: 0,01-0,03, and sodium hydroxide introduce fractional - up to 60% of sodium hydroxide is injected to the full interaction of acetaldehyde with formaldehyde to form pentaerythritol, and the rest at a temperature of 50-70oWith enter after the full interaction of acetaldehyde with formaldehyde. Next, the reaction solution is evaporated to a specific gravity of 1.28-1,32 g/cm3and crystallized pentaerythritol slow cooling to 25oWith a selection of pentaerythritol by filtration, washing with water and returning the wash water after the separation of pentaerythritol to evaporation and the allocation of pentaerythritol and drying, and subsequent isolation of sodium formiate by its crystallization. As a rule, viparita is,6 mm RT.art., and the mother liquor after separation of pentaerythritol sent for evaporation and secretion of sodium formiate. The method allows to increase yields of pentaerythritol and sodium formate and reduce energy consumption. 2 C.p. f-crystals, 1 table.

The invention relates to the technology of polyols, in particular pentaerythritol used in paint and other industries, and sodium formate used in the chemical, leather and other industries.

A known method of producing pentaerythritol (and.with. The USSR 1728215, IPC C 07 C 31/24, 1992), which includes the interaction of acetaldehyde with formaldehyde in an aqueous medium in the presence of sodium hydroxide when a molar ratio of 1: 6: 1,05, followed by distillation and the release of excess formaldehyde. As a result of processes in electrodialyzer flowing under the action of electric current, the content of sodium formiate in the working solution decreases and increases its concentration in the mineralizer. The selection of sodium formiate before the crystallization of pentaerythritol improves its quality.

Thus, in the method proposed before the crystallization of pentaerythritol to allocate formate sodium that will further improve.to. using rectification first allocate the excess formaldehyde, then formate sodium.

To improve the quality of pentaerythritol are various ways of conducting its crystallization and drying.

Thus, in the patent of the Russian Federation 2110508 (IPC 07 With 31/24, 29/38, 1998) offered during crystallization of pentaerythritol reaction mass is subjected to pulsating mixing with an amplitude of 0.2-0.5 m and a frequency of 10-40 oscillations per minute, and cooling to hold speed with temperatures 2-4oWith between adjacent stages, and part of the reaction mixture in the amount of 10-20% of the total return with each subsequent stage of cooling to the previous one. Upon receipt of pentaerythritol as a by-product formed methylformate, which is a valuable product.

The disadvantage of this method are significant energy consumption for the rectification of excess formaldehyde and complexity of the technological process of selection of pentaerythritol.

In the patent of the Russian Federation 2078758 (IPC 07 With 53/06, 31/24, 1997) proposed a method of obtaining sodium formate by evaporation of the mother liquor obtained after separation of pentaerythritol from the reaction mass by condensation of formaldehyde with acetalde="ptx2">

This method allows to significantly improve the quality of sodium formiate at the expense of certain parameters of the technological mode of removing it from the mother liquor after separation of pentaerythritol from the reaction mass, but the disadvantage of this method is its intensity.

The closest technical solution to the claimed is a method of producing pentaerythritol (RF patent 2078073, IPC C 07 C 31/24, 1997), which includes the interaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, distillation and evaporation of the reaction solution, crystallization by cooling, filtration, washing and drying of the finished product. The pre-crystallization is performed under vacuum at a residual pressure of 28-3 kPa within 15-30 min while cooling the solution to 55-75oWith and then for 40-80 min at atmospheric pressure.

The inventive method improves the efficiency of the process of crystallization of pentaerythritol by improving the conditions of formation and growth of crystals.

However, the drawback of this method is the presence of a stage of removal of excess formaldehyde and the lack of quality of pentaerythritol.

Problem solved real sobreda on simple technology and with minimum energy consumption.

The task is solved by the method of simultaneous receipt of pentaerythritol and sodium formate, which includes the interaction of acetaldehyde with an excess of formaldehyde in the presence of sodium hydroxide, evaporating the reaction solution, the crystallization of pentaerythritol cooling, filtration, washing and drying of pentaerythritol and the subsequent allocation of sodium formiate by its crystallization. The process is continued until complete conversion of aldehydes in the presence of sodium hydroxide, boric acid or borax at a molar ratio 1:6-8:1,95-2,55:0,01-0,03, moreover, the sodium hydroxide is injected fractional - up to 60% of sodium hydroxide is injected to form pentaerythritol, and the rest at a temperature of 50-70oWith enter after the full interaction of acetaldehyde with formaldehyde.

Evaporation of the solution for isolation of pentaerythritol crystallization is carried out at a temperature of 80-95oAnd in the vacuum of 0.54-0.6 mm RT.article until specific gravity privelage solution of 1.28-1,32 g/cm3.

After evaporation of the solution to a specific gravity of 1.28-1,32 g/cm3it is slowly cooled to 25oC.

After separation of pentaerythritol filtration washed with water and dried, the mother liquor after allocated is TRITA.

In the known solutions upon receipt of pentaerythritol by the interaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide by-product is sodium formate, which is released from the mother liquor. We propose to obtain pentaerythritol and sodium formate under conditions of increasing their output, reducing energy costs.

Such conditions is a certain ratio of acetaldehyde with formaldehyde, sodium hydroxide and boric acid or brown 1:6-8:1,95-2,55: 0,01-0,03. In this solution it is proposed to use an excess of formaldehyde from 50% of the stoichiometric and above.

In the known solutions, we used an excess of formaldehyde to 50%, and the excess formaldehyde after the reaction allocate rectification, which causes additional energy costs and requires additional equipment.

In the proposed method, an excess of formaldehyde after receipt of pentaerythritol is fully converted to the sodium formate with a second feed of sodium hydroxide, to increase the yield valuable by-product is sodium formate.

The amount of sodium hydroxide in the second stage feed in the reaction mixture should b odaca sodium hydroxide in the reaction mixture creates at the stage of synthesis of pentaerythritol conditions, contributing to the formation of the main product, while suppressed the formation of by-products. The obtained pentaerythritol allocated by evaporation. When carrying out the evaporation of the reaction solution are preferred the following conditions: temperature 85oC and a pressure of 0.54 mm RT.article Evaporation is carried out before specific gravity of 1.28-1,32 g/cm3. Formed supersaturated solution during slow cooling which crystals of pentaerythritol get bigger and clearer, this increases the yield of pentaerythritol and its quality. Wash water after washing the pentaerythritol is sent to the stage of evaporation of pentaerythritol, which contributes to improving the quality of pentaerythritol and increase its output.

After separation of pentaerythritol liquid phase with sodium formate and containing traces of pentaerythritol sent to evaporation of the crystallization of sodium formiate. Allocated formate sodium contains pentaerythritol in an amount of 1.5-3%.

The table shows the conditions for obtaining pentaerythritol and sodium formate and their characteristics.

The following examples illustrate the proposed solution.

Example 1

In a flask with a volume of 1 l at rabotaysam solution in a number 368,4 g), add 24 g of 100% NaOH (use the NaOH solution in the amount of 61.5 g, having a concentration of at 39.3 wt.%), add 0,57 g of boric acid and 285 g of water. Within 20 minutes evenly metered technical acetaldehyde in the amount of 22 g (acetaldehyde has a concentration of 44.7 weight. % and the amount of solution is 49,16 g). The reaction mass is heated to 50oWith and add 21 grams of 100% NaOH. The reaction is carried out to complete conversion of the aldehyde, and then at the end of the reaction is acidified to a pH of about 6.5-6.8. The reaction mixture was evaporated to a specific gravity of 1.28 g/cm3cool it to 25oWith separate precipitated in the sediment pentaerythritol. The pentaerythritol is washed, the wash water is returned back to the evaporation for the selection of pentaerythritol. Of the remaining filtrate by evaporation to his specific weight of 1.4 g/cm3with subsequent cooling to 32oTo produce sodium formate.

After separation of sodium formiate remains the filtrate technical pentaerythritol (FTP) is a valuable product in construction and the leather industry.

Examples 2-3

Similar to example 1, only differ in the quantity of substances and conditions of allocation of pentaerythritol and sodium formate, and in example 2 use borax.

Example 4 (according to protet the tion mixture is acidified to pH 6,0, is subjected to rectification in a laboratory distillation column and remove excess formaldehyde. This is followed by evaporation to achieve a specific weight equal to 1.28 g/cm3evaporated the solution is cooled to 25oWith and allocate filtering pentaerythritol. The obtained pentaerythritol recrystallized in hot water. The filtrate after separation of pentaerythritol is evaporated to a density of 1,425 g/cm3and cooled to 37oTo produce sodium formate.

As seen from the above examples and tables, the proposed method for simultaneous receipt of pentaerythritol and sodium formate allows to obtain high quality and simple energy-saving technology without waste. After separation of sodium formiate remains the filtrate technical pentaerythritol, which is also used in the construction and leather industry.

1. The method of simultaneous receipt of pentaerythritol and sodium formate, including the interaction of acetaldehyde with an excess of formaldehyde in the presence of sodium hydroxide, evaporating the reaction solution, the crystallization of pentaerythritol slow cooling to 25oWith a selection of pentaerythritol by filtration, washing with water and drying, and the accordance of boric acid or borax to the complete transformation of the original aldehyde in a molar ratio of acetaldehyde: formaldehyde: sodium hydroxide:boric acid or borax= 1:6-8:1,95-2,55:0,01-0,03, moreover, the sodium hydroxide is injected fractional - up to 60% of sodium hydroxide is injected to the full interaction of acetaldehyde with formaldehyde to form pentaerythritol, and the rest at a temperature of 50-70oWith enter after the full interaction of acetaldehyde with formaldehyde and evaporation of the reaction solution lead to the specific gravity of 1.28-1,32 g/cm3and wash water after separation of pentaerythritol return to evaporation and the allocation of pentaerythritol.

2. The method according to p. 1, characterized in that the evaporation of the solution for isolation of pentaerythritol crystallization is carried out at a temperature of 80-95oAnd in the vacuum of 0.54-0.6 mm RT. Art.

3. The method according to PP.1 and 2, characterized in that the mother liquor after separation of pentaerythritol sent for evaporation and secretion of sodium formiate.

 

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