Method for preparing crystalline nitrilotrimethylphosphonic acid disodium salt monohydrate

FIELD: chemical technology.

SUBSTANCE: invention relates to technology for synthesis of crystalline nitrilotrimethylphosphonic acid sodium salts. For synthesis of nitrilotrimethylphosphonic acid disodium salt monohydrate the method involves preliminary synthesis of nitrilotrimethylphosphonic acid by interaction of phosphorus trichloride, formaldehyde and ammonia or its derivative followed by neutralization with sodium hydroxide in the content in the reaction mass 46-54 wt.-% of nitrilotrimethylphosphonic acid and 6.0-16.0 wt.-% of hydrogen chloride up to pH value 2.5-4.5, and isolation of the end compound by crystallization. The mass part of the main substance in synthesized product is 88-95%, the content of chloride ions is 1.2-2.0%, yield is 50-60% as measured for PCl₃. Synthesized compound is recommended for using as chelate compounds as a component of detergents, anti-rheological additive in drilling solutions, plasticizing agents for building concretes, in wine-making industry, as inhibitors of salt depositions in heat and power engineering and others fields.

EFFECT: improved method of synthesis.

2 tbl, 12 ex

The invention relates to the technology of crystalline sodium salts of nitrilotriethanol acid, recommended for use as complexing agents in the compositions of synthetic detergents, antibiological additives in the composition of drilling fluids, plasticizers construction of the concrete in the wine industry, as inhibitors in the heat, etc.

Closest to the proposed invention is a method of obtaining a disodium salt of nitrilotriethanol acid, recommended for use in the food industry, particularly in the wine industry for demetallization of wine. The method includes the prior receipt of crystalline nitrilotriethanol (NTF) acid, its dissolution in water up to 30-50% solution, neutralized with caustic soda to a pH of 2.5÷3,4 and isolation of the target product by crystallization and drying under vacuum. This method allows to obtain a product with a basic substance content of at least 96 wt.% (RU # 2131433, MKI 07 F 9/38, publ. 1997).

The disadvantages of this method include an additional stage of selection crystalline NTF, due to this increased amount of waste and therefore increase the cost of production, which limits its scope.

Objective of the solution is aimed invention, is obtaining crystalline disodium salt NTF acid without intermediate the selection of crystalline NTF acid with the full waste disposal and receipt of in-demand products.

This task is solved in that in the known method of obtaining disodium salt NTF acid, including obtaining preliminary NTF acid by the interaction of phosphorus trichloride, formaldehyde and ammonia or its derivative, neutralization with caustic soda and the selection of the target product by crystallization, according to the invention the neutralization is carried out at a content in the reaction mass 46÷54 wt.% NTF acid and 6.0÷to 16.0 wt.% hydrogen chloride to pH 2,5÷4,5.

The process is as follows.

Get NTF acid by the interaction of phosphorus trichloride with an aqueous solution of urotropine in excess of formaldehyde at a temperature of 35-60°and removing excess hydrogen chloride to 6-16 wt.% in the reactor-doznavatel at temperatures up to 120°C. the Reaction mass synthesis NTF acid content of the basic substance 46÷54% and hydrogen chloride 6÷16 wt.% neutralize 44% aqueous sodium hydroxide solution in the crystallizer at a temperature of 70-90°to a pH of 2.5 to 4.5. Next are the crystallization of the salts at a temperature of 10-60°C. the resulting suspension crystallizing sodium salt NTF acid is Orlando sent to centrifugation or filtration to isolate a target disodium salt NTF acid dnovotny. Thus, get the product with the content of the basic substance is not less than 89 wt.%, meets the technical requirements for use in the production of CMC, structural concrete, drilling muds, as a scale inhibitor.

Waste generated in the course of obtaining disodium salt NTF acid, it is proposed to dispose of yield commercial products:

- produced hydrogen chloride is removed from the reaction mass, adsorbed water to form a hydrochloric acid content of 25 wt.%, after the introduction of appropriate corrosion inhibitor, a surfactant and water-soluble organic solvent, is implemented as a commercial product - hydrochloric acid inhibited, which is used for processing bottom-hole wells in oil production.

the mother liquor after centrifugation salt with a basic substance content 17-21 wt.% neutralize 44% sodium hydroxide solution to a pH of 10-11, otdovat at a temperature of 40-60°With the evolved ammonia content of 0.005% and receive an aqueous solution of sodium salts NTF acid, recommended for the production of detergents for various purposes. In addition, you can use the mother liquor after modification of a 25% aqueous solution of sodium salts NTF acid (inhibitor of scaling ioms-1) or oksietilidendifosfonovaya acid is the same as inhibitors in the heat.

Example 1

In chetyrehosnuju glass flask with a capacity of 1 DM³fitted with mechanical stirrer, two funnels and drip refrigerator connected to a absorption of hydrogen chloride, was placed 100 g of 36% hydrochloric acid. Then simultaneously metered into the reactor a mixture of urotropine in excess of formaldehyde, obtained pre-mixture at 45°With 41 g of 25% aqueous ammonia solution (0.6 M NH₃and 146 g of a 37% solution of formaldehyde (1.8 M CH₂O), and 197 g 98 chloride phosphorus (1.4 M PCl₃). The dosage is carried out at a vigorous stirring of the reaction mass and the temperature is 35÷60°, which is supported by the rate of addition of reagents and external cooling. After dosing the reaction mass is heated to 100°C and maintained at this temperature for 1÷1.5 hours for more complete removal of released hydrogen chloride, which catch in the absorbing system. Then the reaction mass is analyzed by the mass fraction of hydrogen chloride (8.2%) and NTF acid (46.4 per cent).

Upon reaching the desired degree of Stripping hydrogen chloride (6÷16%), the reaction mass (suspension) is cooled to 25-30°and with vigorous stirring, added dropwise 44% caustic soda solution. The neutralization reaction proceeds with evolution of heat, and the reaction mixture is heated to 50-80°C. Dosing sche the eyes cease, when the pH of the solution reaches 3,5 (weight added 44% alkali 151,2 g).

After the reaction mass was incubated for 2 hours with continuous stirring, then cooled to 20°C, the resulting suspension was filtered and the crystalline precipitate is dried.

Obtain 102 g of the product with quality indicators:

- mass fraction of the main substances in terms of the disodium salt of NTF acid dnovotny - 90,6%;

- mass fraction of chloride ion to 1.7%;

acid number 431 mg KOH/g

Output 54.7% of theoretical calculated at PCl₃.

The resulting product composition corresponds disodium salt NTF acid dnovotny (see table 1).

The mother solution, resulting in the number of 337 g, is subjected to processing as described below in example 11.

Agathou hydrochloric acid in the amount of 645 g, resulting from the absorption of hydrogen chloride, is processed as described below in examples 11, 12.

Examples 2-10.

The process is carried out analogously to example 1 with changes in the extent of Stripping of hydrogen chloride in the reaction mass, conditions neutralization and crystallization of disodium salt NTF acid dnovotny. The results are presented in table 2.

Example 11.

To 99,3 g abgaznaya hydrochloric acid with mass fractions of the basic substance is not less than 25%, obtained in the conditions of the synthesis reaction mass NTF acid (example 1), dobavlaut 0.02 g of corrosion inhibitor (primary amines fraction ₁₀-C₁₄), 0.1 g of nonionic surface-active substances and 0.56 g of technical formalin.

After mixing, the product meets the quality indicators THAT 2458-12966038-99.

Example 12.

To of 50.4 g abgaznaya hydrochloric acid with mass fractions of the basic substance is not less than 25%, obtained in the conditions of the synthesis reaction mass NTF acid (example 1)add 0.8 g of the corrosion inhibitor, 1.0 g of nonionic surface-active substances, 10.0 g of lignosulfonate, of 9.8 g of methanol and 28 g of water.

After mixing, the product meets the quality indicators THAT 2458-005-27823669-2002.

The method of obtaining crystalline disodium salt of nitrilotriethanol acid dnovotny, including the prior receipt of nitrilotriethanol acid by the interaction of phosphorus trichloride, formaldehyde and ammonia or produced in the water, neutralization with caustic soda and the selection of the target product by crystallization, characterized in that the neutralization is carried out at a content in the reaction mass 46 to 54 wt.% nitrilotriethanol acid and 6,0-16,0 wt.% hydrogen chloride to pH 2,5÷4,5.