HU192796B - Process for producing 1-hydroxy-ethane-1,1-diphosphonic acid with acylating phosphonic acid - Google Patents

Abstract

1-hydroxy-ethane-1, 1-di-phosphonic-acid is prepd. by starting from phosphorus-trichloride and using less acetic-acid and more water than in the usual synthesis to produce in the same reaction mixt. simultaneously the phosphonic-acid and the acylating agent. The reaction is controlled by the sequence of additions, by keeping the appropriate temp. and pressure and by using a catalyst.

Description

The present invention relates to a process for the preparation of 1-hydroxyethane-1,1-diphosphonic acid by acylation of phosphonic acid (phosphoric acid) with simultaneous synthesis of acylating agent using phosphorus trichloride with high yields of both phosphorus trichloride and acylating agent.

It is known that in the case of industrial waters, which are mostly used for cooling, due to various factors, deterioration of the water-contacting (primarily iron) materials, deterioration of the water quality and decrease of the cooling efficiency are also expected. These cause corrosion and rusting, limescale formation and harmful deposits, which can usually be eliminated or limited by treating water with excipients. One of the most effective adjuvant components for low-concentration processing of industrial waters is the 1-hydroxyethane-1,1-diphosphonic acid (HEdF), which can be produced by phosphonic acid acylation, for which many processes are known.

Methods for the production of HEdF by phosphonic acid acylation, among others, are described in the .Metodü polucsenija himicseszkih reacttivov i preparatov '(IREA, Moscow, 1970). An overview of Lastovsky, R.P., et al., pp. 150-155 is given in the book. Accordingly, starting from phosphonic acid is possible with relatively few strong acylating agents, i.e., little acetic anhydride or little acetyl chloride, and starting with phosphoric trichloride, many anhydrous or many low-water acetic acids, i.e., many weak acylating agents. On this basis, in the first case, the separate production of phosphonic acid (and often also the acylating agent) is difficult, and in the second case, the production of HEdF is rendered uneconomical by the slowness of acylation, excess acetic acid utilization and excess acetyl chloride formation.

The process disclosed in German Patent Publication No. 2,345,199 uses a variable mixture of phosphorus trioxide and phosphonic acid as the acylating agent in a variable ratio of acetic acid and acetic anhydride for the preparation of HEdF. The process also involves the removal of excess acylating agent and the decomposition of the formed acylated and condensed acids formed. Although this method provides higher yields and replaces the reagents with more readily available and more readily manageable components based on the amount of phosphorus trioxide and phosphonic acid introduced, its use requires a significant excess of reagents due to its low acylation rate.

In U.S. Patent No. 959,360, they use phosphorus trichloride and excess glacial acetic acid to enhance and sustain the rate of HEdF synthesis, which, in addition to producing excess acetyl chloride, provides the required phosphonic acid and excess acylating agent. The process makes the reaction quick and complete by the addition of additional acetic anhydride, and the HEdF yield is improved by subsequent steam-hydrolysis of the over-acylated and condensed acids. Although this method achieves rapid and complete acylation at near full utilization relative to phosphorus trichloride, the rapid and complete reaction requires very high and uneconomic acetic acid (glacial acetic and acid anhydride intake and acetic acid recovery) under the conditions used.

U.S. Patent 4,060,546 discloses a process for the preparation of HEdF which comprises addition of acetic acid containing up to 1 to 1 molar ratio of water to phosphorus trichloride in various order, followed by reaction for several hours at 80 to 200 ° C. with heating. Although this solution significantly reduces excess acetic acid turnover and excess acetyl chloride formation, it is still disadvantageously high, but the acylation rate is already unfavorably low.

In contrast, it has been found that starting from phosphorus trichloride, using less acetic acid and more water than the known methods, with a small excess of acetic acid in the presence of a catalyst, the appropriate addition of reagents and conducting the reaction under pressure,

2FC13 + CH3COOH + 5H2O - CH3COH [PO (OH2)] 2 + 6HC1 Gross Reaction Equation, Acylation and Phosphonic Acid Preparation, Phosphoric Acacylation and HEdF Synthesis with Good Yield and Low By-products is feasible.

The present invention relates to the implementation of a reaction for the production of HEdF by phosphonic acid acylation which promotes the synthesis of effective reagents for acylation, provides a temporary excess of phosphonic acid to limit byproduct formation and improves HEdF synthesis, and also enhances the efficiency of acylation. According to this, phosphorus trichloride is introduced at atmospheric pressure, at a temperature of 20-35 ° C, preferably 25-30 ° C, with stirring at a molar ratio of 0.1-0.4: 1, preferably 0.2-0.4: 1, based on the phosphorus compound. in the presence of glacial acetic acid, with the removal of hydrochloric acid gas, to water added in a molar ratio of 1.5 to 2.5: 1, preferably 2: 1, to convert phosphorus trichloride into phosphonic acid by rapid reaction. Thereafter, the mixture is stirred at atmospheric pressure, 25 to 40 ° C, preferably 30 to 35 ° C, with stirring, in a ratio of 0.4-0.8: 1, preferably 0.5-0.7: 1, based on the phosphorus compound. glacial acetic acid and water at a molar ratio of 0-1.0: 1, preferably 0.5: 1, based on the above 2.5: 1 molar ratio of water to phosphorus compound, or

Instead, the amount of acetic acid corresponding to a molar ratio of 0.4-0.8: 1, preferably 0.5-0.7: 1 to phosphorus compound, and 0-1.0: 1 still missing from the amount of water calculated for the phosphorus compound water, preferably in a molar ratio of 0.5: 1. Finally, with or after the glacial acetic acid addition, anhydrous zinc salt, preferably zinc chloride, corresponding to a concentration of 0.01 to 10% (w / w), preferably 0.1 to 1.0% by weight, is added to or added to the mixture. The following sub-processes are executed or started during chemical dosing:

2 / 3PCb + 5HzO -> 1 2 / 3P (OH) ₃ + 5HCl 1 / 3PC13 + CH3COOÍI -> 1 / 3P (OH) ₃ + CH3COC1 2P (OH) ₃ + CH3COC1 -> CH ₃ COH [PO (OH) 2] 2 + HC1

After chemical addition, the temperature of the reaction mixture is gradually increased to 50-80 ° C and the pressure is increased gradually to 2-5 bar and the mixture is stirred at this temperature and pressure for 1-5 hours. Subsequently, the excess excess and unreacted acetyl chloride is distilled off by reducing the pressure. The temperature is then raised to 100-140 ° C and the pressure is adjusted to 1-5 bar and the reaction mixture is stirred at this temperature and pressure for 1-4 hours. Finally, the mixture is heated at 110-130 ° C, preferably 115-125 ° C, at atmospheric pressure to remove a small amount of excess acetic acid, decompose the little acylated HEdF, and partially adjust the concentration of the solution for processing.

The process according to the invention can also be advantageously carried out by adding small amounts of acetic anhydride or acetyl chloride to the reaction mixture at the end of the chemical additions, in a small excess of acylating agent, in place of or mixed with glacial acetic acid.

Thus, according to the invention, phosphonic acid acylation can be carried out with yields greater than 95% relative to phosphorus trichloride, greater than 40% relative to acetic acid, and HEdF production can be utilized elsewhere with hydrochloric acid and few other or recycled acetic acid byproducts. can be achieved by obtaining the final product in concentrated aqueous solution.

Example 1

In a 6.3 m ³ enameled autoclave with stirrer, thermometer, reflux condenser and distillation head, 720 kg (40 km) of water and 360 kg (6 km) of glacial acetic acid are aspirated. The system is then flushed with nitrogen and then 2750 kg (20 km) of phosphorus trichloride are added slowly through a suitable dosing system under cooling and stirring. The temperature of the reaction mixture was maintained at 25-30 ° C with a thermostat. (At the beginning of the addition, this requires strong cooling, hereinafter referred to as "weak heating".) Then, or in the case of a mixing disadvantageous consistency, a small excess of 900 kg (15 km) of glacial acetic acid and 180 kg (10 km) of water is added. Hydrochloric acid gas and a small amount of acetyl chloride are formed during the addition, so the gases / vapors are passed through an aqueous wash sink. At the end of the addition, 5 kg of anhydrous zinc chloride was added to the reaction mixture. The temperature is then gradually raised to 75 ° C, while the pressure of the formed and reactive acetyl chloride does not exceed 4 bar. The mixture was then stirred for 4 hours under these conditions. Further, by slightly reducing the temperature and pressure, a slight excess of acetyl chloride is distilled off, and the temperature is gradually raised to 125 ° C and the pressure to 3 bar. Under these conditions, the reaction is carried out for 1 hour. The temperature and pressure were lowered again to distillation, and the reaction mixture was blown off with steam at 130 ° C to remove excess hydrochloric acid in aqueous acetic acid. The acid and anhydrous product has a hot syrup density which solidifies on cooling. It is formulated according to the conditions of use, preferably by dilution with an equal mass of water (50% solution).

The anhydrous product weighs 2025 kg and has a HEdF content of 97% by weight. The yield of HEdF calculated for phosphorus trichloride is 95%.

Example 2

The autoclave of Example 1 and the amounts and order of addition of Example 1 were used, except that glacial acetic acid required in the acylation step and then 800 kg glacial acetic acid and 40 kg acetic anhydride instead of water was added, followed by 240 kg 25% ( Aqueous acetic acid (m / m) which is a by-product of the synthesis of Example 1 is added. Otherwise, the procedure of Example 1 is also followed.

The resulting 50 wt% aqueous solution had a weight of 4060 kg, anhydrous product purity (HEdF content) 97.5 wt% and a yield based on phosphorus trichloride of 96%.

Example 3 (Counterexample) The autoclave of Example 1 and the dosing volumes and sequence of Example 1 were worked except that reflux but no overpressure was used during the temperature rise to 95 ° C. In the following, the procedure of Example 1 is followed.

The resulting anhydrous product had a weight of 2012 kg and a HEdF content of 92% by weight. Yield: 90% for phosphorus trichloride.

Example 4

In a 6-L glass flask with stirring, thermometer, reflux and distillation, which can be cooled and heated externally, the reagents are added according to the order of Example 1 and in g, and run as in Example 1. reaction temperature program except that only reflux is used instead of pressure. Finally, after evaporation of the by-products, the solution is adjusted to a concentration of 50% by weight in the dry matter. The resulting solution had a weight of 4040 g and a HEdF content of 91.5% by weight on a dry basis. Yield: 90% based on phosphorus trichloride.

Example 5 (Counter Example) In one of the two experiments performed in Example 4, the addition of zinc chloride to the reaction mixture was omitted, and in the other, to the total amount of prepared glacial acetic acid and water (1260 g glacial acetic acid and 900 g water). In both cases, the dry matter content and the weight of the 50% solution are reduced, and in the second experiment, the bulk of the material is phosphoric acid (phosphonic acid) rather than HEdF. The yield calculated for phosphorus trichloride is 86% in the first case and 60% in the second case.

Claims (2)

A process for the preparation of 1-hydroxyethane-1,1-diphosphonic acid from phosphorus trichloride, characterized in that the phosphorus trichloride is stirred at a temperature of 20-35 ° C, preferably 25-30 ° C, based on the phosphorus compound. In the presence of glacial acetic acid in a molar ratio of 0.1 to 0.4: 1, preferably 0.2 to 0.4: 1, added to water at a molar ratio of 1.5 to 2.5: 1, preferably 2: 1, based on the phosphorus compound, and then to the mixture. 25-40 ° C, preferably 30-35 ° C, acylating agent, glacial acetic acid or at most 0.4-0.8: 1, preferably 0.5-0.7: 1 molar, based on the phosphorus compound. Glacial acetic acid mixed with 20% by weight of acetic anhydride or acetyl chloride and the remaining 0-1.0: 1, preferably 0.5: 1 molar ratio of water to the 2.5: 1 molar ratio of stoichiometric water to phosphorus are added together with or after the glacial acetic acid addition. , with 0.01- Anhydrous zinc salt, preferably zinc chloride, is added in an amount of 10% by weight, preferably in the range of 0.1 to 1.0% by weight of zinc ion, followed by refluxing the acetyl chloride at 50-80 ° C. After heating for 1 to 5 hours, the excess acetyl chloride is distilled off under reduced pressure, then the temperature is raised to 110-140 ° C and pressure for a further 1-4 hours. It is increased to 1 to 5 bar, finally by the addition of water vapor, the excess aqueous acetic acid is removed by distillation in a known manner. Process according to claim 1, characterized in that the post-reaction is first carried out at a temperature of 70-80 ° C and a pressure of 3-4 bar, The reaction is carried out for 2 to 3 hours and then at 115-125 ° C and 1 to 3 bar for 1 to 3 hours. Without drawing The Director of Economic and Legal Publishing is responsible for the publication 88.564.66-4 Alföldi Nyomda Debrecen - Chief Executive Officer: István Benkő Chief Executive Officer