DD266933A3 - PROCESS FOR PREPARING 2-CHLOROETHANOPHOSPHONIC ACID - Google Patents

Abstract

The invention relates to a process for the preparation of the growth regulator used as 2-chlorethanphosphonsaeure. The process proceeds via the known intermediates tris (2-chloroethyl) phosphite, 2-chlorethanphosphonsaeure- bis (2-chloroethyl) ester and its acidolysis by means of hydrogen chloride. According to the invention, the reaction of phosphorus trichloride and ethylene oxide is carried out in the presence of - based on the amount of tris (2-chloroethyl ether) phosphite present as a solvent - from 0.03% by weight to 0.2% by weight of dichloroethyl ether, in the reactor by partial or total return of the condensed Brueder the subsequent isomerization a dichloroethane concentration between 20 wt .-% and 60 wt .-% is adjusted.-For acid hydrolysis in countercurrent to 2-chloroethane-phosphonsaeure- bis (2-chloroethyl) ester by passed a reactor cascade.

Description

Characteristic of the known technical solutions

For the preparation of 2-Chlorethanphosphonsäure are from the literature various Voi drive known gowordon. For example, it is proposed in US Pat. No. 3,833,645 to produce the phosphoric acid by hydrolysis of its dichloride. The dichloride is known to be produced from phosphorus trichloride, ethylene and oxygen (DE-OS 2032135, DR-OS 1103922) or from phosphorus oxychloride and ethylene (DE-OS 2032136); The reaction mixture obtained by reaction with phosgene at temperatures above 90 ° C. is also obtainable from the reaction mixture obtained in the heating of 2-chloroethanephosphonic acid bis (2-chloroethyl) ester (German Offenlegungsschrift No. 2,132,962) It is also proposed to chlorinate ethanephosphonic dichloride with elemental chlorine to give a mixture of 1- and 2-chloroethanephosphonic dichloride (DE-OS 2023050), and it is also proposed to chlorinate ethanephosphonic dichloride with elemental chlorine to give a mixture of 1- and 2-chloroethanephosphonic dichloride It is known to prepare 2-chloroethanephosphonic acid from 2-acyloxyethanephosphonic acid or ester esters by reaction with hydrogen chloride (DE-OS 2053367) .These processes are hardly suitable for commercial use in ochnology because the outward products required are generally difficult to obtain.

All technical processes for the preparation of 2-chloroethanephosphonic acid are based on the method described for the first time by Kabachnik and co-workers (Chem. Abstr. 42 (1942), p. 7241), since the starting components phosphorus trichloride and ethylene oxide are available industrially

 The three-step process follows the following Schoma:

PCl ₃ + 3 H ₂ C - CH _a - * P (OCH ₂ CH ₂ Cl) ₃ (i) P (OCH ^ CHqCI) ^ ¹¹ U- Cjkywii ^ nr \ "vnn" MftWJ./n /.ι, Cl CH CH _{9 9} P (OCH ₀ CH ₉ Cl) ₉ "Cl CH ₉ CH ⁵ ₉ i (OH)" *

* = il * «* * * ^c / J ^c (III)

O O

2 Cl CH ₉ CHpCl

The seemingly clear procedure brings many problems in αώ large-scale application, and therefore it has not been recommended to seek to improve the efficiency of the individual process steps.

Kabachnik already points out that in the first stage 0 to 20%, in the second stage even more than 50% of a non-distilling residue is formed.

In addition, the isomerization reaction is highly exothermic without solvent - almost explosive - and involves the danger in large-scale production that the approaches can easily get out of control.

The use of inert solvents, ζ. B. of "dichlorobenzene, carbon tetrachloride or chlorobenzene, both in the Although the preparation of the tris (2-chloro-thio / l) -ptio8phite (stage I) and in the subsequent isomerization (stage II) leads to a

There is a reduction in side reactions, but then requires elaborate separation procedures to remove the solvents again.

It has therefore been proposed that phosphorus trichloride and ethylene oxide are used as the reaction medium in tris (2-chlorothyl) pho8phlt

To react and the resulting tri- (2-chloroethyl) phosphite so in a preheated to 18O ⁰ C to 200 ⁰ C reaction vessel in which is already 2-Chlorethanphosphonsaure-bis (2-chloroethyl) ester, dosleren that the reaction without wide

Supply of heat passes. The yields given in DD-PS 107057 were after esterification of the samples with diazomethane

Chromatography is determined. However, the values found by the so-called 100% method are clearly too high, and our own analyzes using an internal standard showed that volatile products such as HCl or oligomers

Products can not be detected by the 100% method and simulate a higher yield. From DE-AS 1244757 is known to form tris (2-chloroethyl) phosphite only pure colorless PCI ₃ and dry, from

To use polymeric portions of free ethylene oxide and to carry out the reaction in the presence of ß-chloroethanoi as a catalyst, Also iodine, iron (III) chlorld, HCI ₁ H ₃ PO ?, Magnesiumchloi d and amines have been tested as catalysts (US-PS 28772G0, Japanese Patent Publication No. 67/19576, U.S. Patent No. 2,866,808).

The proposed acids, however, favor the formation of undesired by-products. Amines catalyze the Polymerization of Epoxlden. The Acldolyso of Dlesters to phosphonic acid (stage III) is apparently the most difficult step of the overall process. The Consecutive rupture leads over the half-ester, which is then cleaved to phosphonic acid. Depending on the Renktlonsbedingungen and the concentration of the reactants, the process in the film of the Bls - ^ - ChlorethyO-chlorethylphosphonates to 45 to 84% 2-Chlorethanphosphonsäure and to 3-30% mono-2-chloroethyl-2

chloroethylphosphonate lead. Therefore, various extraction & procedures for purifying the 2-chloroethanephosphonic acid have become known (USP 3626037 GB-PS 1187002, US-PS 3896163).

A large number of patents deals with the modification of acidolysis. For example, the Acidolysis is known

under autogenous pressure at temperatures between 100 ° C and 145 ⁰ C with a 20 to 45% lgon hydrochloric acid perform (US-PS 3787486).

It is also possible, the cleavage with gaseous hydrogen chloride at elevated pressure with the exclusion of water at Expire temperatures up to 200 ⁰ C (GB-PS 1356688). It has also been suggested that the process be in a first stage

with F'hosgen at 76 ⁰ C to 22O ⁰ C and in a second stage with anhydrous HCl at 140 "C to 22O ⁰ C. It is possible to maintain a certain concentration by batchwise metered addition of hydrogen chloride during the process.

The use of catalysts has also been proposed for the process (DD-PS 231358, DD-PS 231359). Ebenuo has become known, the diester, a mixture of concentrated hydrochloric acid and HCI gas so metered that the

molar ratio between water and diester first at 170 ° C to 18O ⁰ C 3: 1, then at 155 ⁰ C to 165 ⁰ C 0.5: 1, wherein different Verwoilzoiton are observed (DD-PS 149860).

The method has the disadvantage that once treated considerable amounts of unreacted hydrochloric acid or destroyed

and, on the other hand, much chloroethanol is formed instead of 1,2-dichloroethane.

The large number of publications on the preparation of 2-chloroethanephosphonic acid makes it clear that all methods

from the point of view of economic viability, in particular as regards product yield and purity, but not yet to be fully complied with.

Object of the invention

The aim of the invention is βε, one on the intermediates tris (2-chloroethyl) phosphite, 2-Chlorethanphosphonsäure-bis (2-chlorethyl ester and its cleavage by hydrogen chloride Veif ears for the production of 2-Chlorethanphosphonsäure to develop, which makes it possible, cost To produce active substance concentrates of high purity.

Explanation of the essence of the invention

The object of the invention is to avoid the disadvantages of the prior art, which consist mainly in the necessity of separation, polymeric and toxic by-products.

This object is achieved by an ancestor for the preparation of 2-chlororetlianphosphonic by resuspending the starting materials phosphorus trichloride and ethylene oxide in tris (2-chloroethyl) phosphite as a solvent on the intermediates tris- (2-chloridylphosphite, 2-Chlor6thanphosphonsäure bis (2-chloroethyl) ester and its acidolysis by means of water vapor gosättigtem Chiorwanserstoff in a reactor cascade with subsequent addition of 2.5 to 5.5 moles of water per mole of phosphonate used to hot Auldolyseprodukt, the escaping from the cascade residual hydrogen chloride by phosphonate iibsorblert and again desson cleavage used is, according to the invention, the reaction of phosphorus trichloride and ethylene oxide in the presence of - based on the solvent introduced as the amount of tris- (2-chlorethyOphoaphU-0.03Gew .-% to 0.2Gew .-% Dichlorothylüther performs in the reactor by partially or complete return of the condensed vapor of the adj hließenden isomerization setting a Dichlorethunkonzentration between 20 and 60 wt .-% and the Acidolyse the water vapor-saturated hydrogen chloride in countercurrent to 2-Chlorethunphosphonsäure-bis (2-chloroethyl) -electrode directs the reactor cascade.

By applying the invention Veifahrona It is possible - based on phosphorus trichloride and ethylene oxide as starting materials dos Gesampiprozesses-high yields of 2-Chlorothanphosphonsäuro to achieve. At the same time, the proportion of by-products formed by polymerization and apportionment) is decisively reduced; that has u. a. also a lower wastewater pollution by ous process result.

-3- 266 933 Ausfohrungsbolsplele

a) Example (not subject matter of the invention)

In a reactor equipped with a cooling option, 1000 kg of tris-2-chloroethyl phosphite are introduced and, at a temperature of 30 ° C., continuously 274.87 kg / h (6 kmol + 4% excess) of ethylene oxide and 274.74 kg / h of phosphorus trichloride ( 2kmol) initiated. Because of the overflow of the reactor, 544kg / hr of tris-2-chloroethyl phosphite is removed, containing about 2% of unreacted ethylene oxide.

In the nachgeochalteten isomerization step (2), the tris-2-chloroethyl phosphite is isomerized in the temperature range of 170 to 195 ⁰ C to Bls-2-chloroethyl 2-chlorothylphosphonat. Here are constantly distilled 18kg / h of vapor with you composition 60% ethylene oxide and 40% dichloroethane. The phosphonate is about 89% pure. 535 kg / h phosphonate are continuously metered into the saponification stage, which consists of 4 reactors (each 4m ³ content) in a cascade, in the same flow to the phosphonate 334 kg / h of gaseous HCl at temperatures of 155- 1/5 ⁰ C by the Cascade and 2-Chlorethanphosphcnsäure with a yield of 237.55 kg / h 75% igor 2-Chlorethanphosphonsäure obtained. In the resulting vapors, 231 kg / h of dichloroethane and 47.8 kg of chloroethanol are detected. Total yield for ethylene oxide is 59.2%, for PCI ₃ 61.6% (178.16kg 100% CEP / h).

b) Example (subject matter of the invention)

274.87 kg / h (6 k mol + 4% excess) of ethylene oxide and 274.74 lca / h of phosphorus trichloride (2 k mol) are continuously introduced into the same reactor as in Example 1, and 0.5 l / h bis-2-chloroethyl ether (technical grade ) metered. About 544 kg / h of Ti is-2-chlorothylphosphit proceed from the overflow of the reactor, which initially contain 2% of uninterrupted ethylene oxide. In the downstream stage, as in Example 1, the bis-2-chloroethylchloroethylphosphonate is synthesized therefrom. First, 18 kg / h of vapors distill off. These are quantitatively recycled to the reactor of the first stage of the process.

As a result, the concentration of dichloroethane and ethylene oxide in the phosphite reactor increases continuously . The consequence is that also the amount of the vapor increases. The amount of ethylene oxide is reduced in the equilibrium state to 264.4 kg / h. By an appropriate device, the excess dichloroethane is constantly removed from the system when a Dichlorothan concentration of 20-50% is reached. The recirculated Dichlorethanmenge is 4-12 kg / h. It contains 1-5% ethylene oxide as well as bis-2-chloroethyl ether and traces of chloroethanol. The phosphonate forming the isomerization step is 92%. The amount is 536kg / h. In contrast to Example 1, the phosphonate is saponified in countercurrent to the HCl stream with 204kg / HCI / h to 2-Chlorethanphosphons8ure. The saponification takes place in a cascade consisting of 4 reactors (each 4 m ³ content). Conveniently, in this case the first reactor to 17O ⁰ C, the two middle at 165 ⁰ C and the last held at 16O ⁰ C. In this case, pressure differences result in the individual rawactors. Thus, in the last reactor 0.042 MPa, in the reactor 3 0.028 MPa, measured in the reactor 2 0.014 MPa. Dor first Roaktor is depressurized. The amount of HCI is reduced to 160 kg / h when it absorbs from the reaction cascade residual hydrogen chloride is replaced by phosphonate and this is fed back into the reaction.

The yield is 253.66 kg / h 90% CEP-Wirkstof f. 160 ° C hot active ingredient are continuously metered 89-17Skg H ₂ OZh. The overall yield, based on ethylene oxide and PCI ₃ , is 79% (228.29 kg 100% CEP / h). In the vapors accumulate in the sum 322kg Dichlorothan / h.

The product obtained can be processed directly into active ingredient formulations for agriculture without further purification operations; the crops treated with such formulations do not show any phytotoxic effects, even at relatively high cost.

Claims (2)

Process for the preparation of 2-Chloroethanephosphonic by reacting the starting materials phosphorus triochloride and ethylene oxide in tris (2-chloroethyl) phosphite as a solvent on the intermediates tris (2-chloroethyl) phoBphit, 2-Chlorethanphosphonsäure biü (2-chloroethyl) ester and its acidolysis by means of water vapor saturated hydrogen chloride in a reactor cascade with subsequent addition of 2.5 to 5.5 moles of water per mole of phosphonate used to the hot Acidolyseprodukt, wherein the escaping from the cascade residual hydrogen chloride is absorbed by phosphonate and used again for the cleavage, characterized in that the Reaction of phosphorus trichloride and ethylene oxide in the presence of - based on the ais solvent vorgelogte amount of tris (2-chloroethyl) phosphite - 0.03Gew .-% to 0.2Gew .-% dichloroethyl ether, wherein in the reactor by partial or total recycle the condenser vapor of the subsequent Isomerisierungsstufe a Dichlorethankonze is adjusted between 20 and 60Gow .-% and for acidolysis the water vapor-saturated hydrogen chloride in countercurrent to 2-chloroethanephosphonic acid bis (2-chloroethyl) estsr passes through the reactor cascade. Application «area of the invention The invention relates to a process for the preparation of 2-chloroethanephosphonic acid which proceeds via the intermediates tris (2-chlorothyl) phosphite 2-chloroethanephosphonic acid (2-chloroethyl) and its cleavage by means of hydrogen chloride. Phosphonic acid is widely used in agriculture as a growth regulator.