DE2920172A1 - Thio:phosphonic acid O-ester chloride cpds. prodn. - by reaction of di:thio:phosphonic acid O-ester cpds. with chlorine and removal of pptd. sulphur - Google Patents

Abstract

In a new process for the prodn. of thiophosphonic acid O-ester chlorides of formula (I) by reaction of corresp. dithiophosphonic acid O-esters of formula (II) with Cl2 and separating precipitated sulphur from the reaction prod. (where R and R1 are organic residues). (a) (II) is reacted with ca. 1.5 molar proportions of Cl2 to give a mixt. of (I) and S2Cl2; (b) this mixt. is treated with about the same amt. of (II) as was used in step (a) so as to yield a mixt. of (I), bis-O-alkylthiophosphenyl disulphide of formula (III) and sulphur; (c) the crystalline sulphur is filtered off; (d) (I) and any inert solvent used are distilled off from (III); (e) the disulphide (III) is reacted with ca. 2 molar proportions of Cl2 to give a mixt. of (I) and S2Cl2; and (f) this mixt. is either reacted with (II) as in step (b) or reacted with H2S to convert the S2Cl2 into S + HCl, (I) being subsequently distilled off from the sulphur. (I) are intermediates, especially for plant protection agents. By carrying out the process in the specified manner, by prod. sulphur is obtd. in crystalline form and is therefore easily sepd. off. The chlorine is fully utilized. (I) is obtd. in good yield and high purity.

Description

Process for the production of thiophosphonic acid-O-ester-

Chloride thiophosphonic acid-O-ester-chlorides are interesting intermediates in various fields, in particular for the production of pesticides (see e.g.

U.S. Patents 2,503,390 and 2,988,474; JP-PS 41 09 25 and 41 09 30; DE-OSes 19 39 821, 25 23 324, 26 30 054, 26 39 433 and 27 26 464).

A number of different processes are already used to produce them known, mainly of thiophosphonic acid dihalides or -O, O-diesters, start from phosphonous acid ester halides or from thiophosphonous acid O-esters (Houben-Weyl, vol. XII / l, p. 561 ff).

All of these manufacturing methods mentioned above are different with suffers from pronounced disadvantages such. B. awkwardly accessible starting materials, Need for auxiliaries, unsatisfactory yield or being difficult separable product mixtures arise.

It is also already known that thiophosphonic acid O-ester chlorides I can be prepared by chlorination of dithiophosphonic acid O-esters II, bis-O-alkylthiophosphonyl disulfides III occurring as intermediate products (Chupp and Newallis, J. Org. Chem., 27, 3832-35 (1962)). This method is based on the following reaction scheme: (R, R '= organic radicals) However, the thiophosphonic acid O-ester chlorides I cannot be produced with satisfactory yields either, with the following additional difficulties: The sulfur formed in the chlorination stage a as well as that in the Disulfur dichloride formed in chlorination stage b is extremely difficult to remove from the reaction products (S2C12 cannot be separated by distillation from compounds I with lower alkyl groups; the sulfur that is formed according to variant a or also sulfur that is formed by hydrolysis of the S2C12 formed according to variant b , is obtained in a greasy form, which makes working up the reaction products considerably more difficult).

These circumstances require additional, uneconomical processing of the resulting wastewater.

It was therefore the task of the production process for the Thiophosphonic acid-O-ester-chloride I from dithiophosphonic acid-O-esters II in such a way that that the problems mentioned do not occur and that the products I are as pure as possible Form and can be obtained in better yields. This task could according to the invention can be solved by a very special reaction procedure of the known method.

The subject of the invention is a process for the preparation of thiophosphonic acid O-ester chlorides of the formula I. where R = alkyl or phenyl radical, preferably straight or branched C1-C12, in particular C1-C4-alkyl radicals; (The phenyl radical can also be substituted, e.g. by halogen or lower alkyl or alkoxy groups) and R '= alkyl radical, preferably with 1-4 carbon atoms, by reaction of the corresponding 0-dithiophosphonic acid ester II where R and R 'have the same meaning as in formula I, with chlorine optionally in an inert solvent, and separating the precipitated sulfur from the reaction product, characterized by the following reaction steps: a) Reaction of the dithiophosphonic acid-O-ester II with chlorine in the mol- Ratio of about 1: 1.5 to a mixture of thiophosphonic acid O-ester chloride I and S2C12, b) adding about the same amount of dithiophosphonic acid O-ester II to this mixture as was also used in step a), whereby then a mixture of bis-O-alkylthiophosphonyl disulfide III (where R and R 'have the same meaning as in formulas I and II), and sulfur is formed, c) filtration of the crystalline sulfur precipitated in stage b) and d) distillation of any solvent used and of the thiophosphonic acid O-ester chloride I of the bis-O-alkylthiophosphonyl disulfide III, e) chlorination of the bis-0-alkylthiophosphonyl disulfide III with about 2 moles of chlorine / mole III to a mixture of thiophosphonic acid 0-ester chloride I and S2C12, which f) by reaction with Dithiophosphonic acid O-ester II according to step b) is converted back into a mixture of I, III and sulfur or g) is reacted with H2S, the disulfur dichloride S2Cl2 being converted into S s HCl, and the thiophosphonic acid O-ester chloride is distilled off I from the sulfur formed.

It was surprising that when the process was carried out, the sulfur was obtained in crystalline and thus easily separable form. It is known that a similar procedure in the chlorination of O, O-dialkyldithiophosphoric acids IV to the corresponding O, O-dialkylthionophosphoric acid chlorides V the sulfur can also be obtained in a readily separable form (DE-OS 25 38 310), but because of the complicated phosphorus chemistry it could not be concluded that what applies to the production of O, O-dialkylthiBnophosphorsäurechloriden V, in the same way also in the Production of thiophosphonic acid Q ester chlorides I applies.

The method according to the invention will now be explained in more detail as follows.

The process is based on a) from the dithiophosphonic acid O-esters II and chlorine in a molar ratio of about 1: 1.5 which are easily accessible by reacting dithiophosphonic anhydride and alcohols. This stage proceeds according to the following reaction equation: As can be seen from the equation, a mixture of thiophosphonic acid-O-ester-chloride I + S2Cl2 is created (in addition to HCl, which largely softens).

b) In the next process stage, this Gsch is now mixed with approximately the same amount of dithiophosphonic acid O-ester II that was also used in stage a). The reaction now taking place can be represented by the following equation: In this reaction, the S2Cl2 is converted into elemental sulfur, which surprisingly occurs in crystalline form. It can therefore easily be separated off - preferably filtered off - in the next process stage c).

d) From the essentially of thiophosphonic acid-O-ester chloride I and bis-O-alkylthiophosphonyl disulfide III and optionally an inert solvent The existing filtrate is then the solvent (if present) and the thiophosphonic acid-O-ester chloride I distilled off. The bis-O-alkylthiophosphonyl disulfide which cannot be distilled without decomposition III normally remains as a residue after distillation.

e) This residue, consisting mainly of III, is now chlorinated with about moles of chlorine / mole of III, a mixture of thiophosphonic acid-O-ester chloride and S2Cl2 being formed; the reaction proceeds essentially according to the following equation: f) This mixture is the same as that which is also formed in reaction stage a) and which is then reacted in stage b) with further starting material dithiophosphonic acid 0-ester II. The mixture of substances resulting from stage e) is therefore returned to stage b).

d) As an alternative to this recycling, however, the reaction product of stage e) can also be reacted with H2S, the S2Cl2 of the reaction product being converted into S and HCl: The thiophosphonic acid O-ester chloride 1 can easily be separated from the sulfur formed, preferably by distillation at this stage. A temperature range between about 20 and 40 ° C. is expedient for all reaction stages. Lower reaction temperatures are of no advantage; At higher temperatures, the reactions are confusing at the expense of the purity and yield of the desired ester halides I. Methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, etc.).

In the above process description the word '8about' means before the quantities or proportions given there, that deviations from the specified Numerical values of 10 to 15% upwards and downwards are possible without significant disadvantages are.

A possible variant of the method according to the invention consists in that the amount of the always remaining residue of bis-O-alkylthiophosphonyl disulfide III keeps low by starting with a low number of moles in reaction stage a) the further reactions in stages b) and e) are carried out until the resulting Reaction mixture, the desired amount of ester chloride I is present, which is then according to the above description is isolated.

Compared to the known process for the preparation of thiophosphonic acid-O-alkyl ester chlorides the method according to the invention has the following advantages: 1. Elimination from Houben-Weyl, vol. XII / 1 p. 561 ff.

known auxiliary components (amines etc.), 2. full utilization of the chlorine used, 3. simple isolation of the reaction products, 4. high yields and degrees of purity of the process products, 5. Elimination of a complex Wastewater treatment.

The process therefore represents a significant step forward.

The following examples are intended to further illustrate the invention to serve.

Example 1 Preparation of methanethiophosphonic acid O-ethyl ester chloride A solution of 312 g of methane-O-ethyldithiophosphonic acid (2 mol) in 600 ml of methylene chloride is gassed with 215 g (3.03 mol) of chlorine while stirring and cooling at 20-30 ° C.

The resulting solution is stirred and cooled with further 312 g of methane-O-ethyldithiophosphonic acid (2 mol) are added at 20-30 ° C. and again gassed as above with 142 g (2 mol) of chlorine.

After a further addition of 312 g of methane-O-ethyldithiophosphonic acid at 20-30 ° C., the methylene chloride is distilled off. Getting out of arrears at 2 torr 564 g of crude distillate distilled off. The residue is extracted by suction, The filter residue is rewashed with methylene chloride and the methylene chloride is distilled off 133 g of sulfur and 300 g of an oil obtained from the mother liquor, which essentially consists of bis-methane-O-ethylthiophosphonyl disulfide.

The crude distillate is redistilled in vacuo on a 30 cm Vigreux column.

This gives 25 g of first run Kpl4 55-63 OC 507 g of methane-thiophosphonic acid 0-ethyl ester chloride vom Kplz 69 - 65 CC, which, according to gas chromatographic analysis, is 98.4% of the main product contains (80 k of theory) and 19 g of residue.

Example 2 Preparation of ethanethiophosphonic acid 0-methyl ester chloride A solution of 156 g of ethane-O-methyldithiophosphonic acid (1 mol) 200 ml in methylene chloride is gassed at 20-30 ° C with 107 g of chlorine (151 mol).

Then the resulting reaction mixture is five times in succession at 20-30 ° C with 156 g of ethane-O-methyldithiophosphonic acid (1 mol) and gassed with 71 g of chlorine (1 mol) at the same temperature and finally with 156 g methane-O-methyldithiophosphonic acid are added.

Then the separated sulfur is sucked off and the filter retainer washed out with methylene chloride. The methylene chloride is distilled off from the filtrate. The residue is roughly distilled in vacuo. 874 g of crude distillate and 259 g of residue were obtained.

By redistillation on the column described under Example 1 are 115 g first run from Kpla 64 - 67 OC, which contains 85 ffi main product and 827 g ethanethiophosphonic acid 0-methyl ester chloride obtained from Kp12 67 ° with 98.7 * purity.

(85.8% of the theory) With the product contained in the flow, this is 96.1 % d.Th, EXAMPLE 3 Production of ethanethiophosphonic acid O-ethyl ester chloride 170 g of ethane-O-ethyldithiophosphonic acid (1 mol) are added with stirring and cooling gassed below 30 ° C with 107 g of chlorine. The reaction mixture is then taken nine times Stirring and cooling at below 30 ° C alternately with 170 g each of ethane-O-ethyldithiophosphonic acid added and gassed with 71 g of chlorine and finally with 170 g of ethane-0-ethyldithiophosphonic acid offset.

After 156 g of precipitated sulfur have been filtered off with suction, the filtrate becomes coarse distilled in vacuo.

1076 g of ethanethiophosphonic acid 0-ethyl chloride are obtained from Kp2 45 - 50 ° C of 94.9% purity, which is achieved by distilling off 10% Increase advance to 98% loads. The distillation residue becomes by increasing with 300 ml of methylene chloride, suction and distilling off the methylene chloride the filtrate isolated a further 113 g of sulfur and 225 g of oil, which essentially consists of Ethane-O-ethylthiophosphonyl disulfide consists and as a starting material for further Preparation of the desired acid chloride can be used.

The above yield corresponds to 84.2% of theory.

Example 4 Preparation of ethanethiophosphonic acid 0-n-propyl ester chloride 184 g of ethane-O-n-propyldithiophosphonic acid (1 mol) in 200 ml of methylene chloride gassed with 107 g of chlorine while stirring and cooling at below 30 ° C.

Then the reaction mixture is alternated six times at 20-30 ° C with 184 g of ethane-O-n-propyl-dithiophosphonic acid and then with 71 g of chlorine fumigated.

Hydrogen sulfide is then passed into the reaction mixture as long as until there is no more hydrogen chloride in the exhaust gases. The ones from the greasy fancy Sulfur (196 g) decanted liquid is distilled as in the previous examples worked up.

1265 g of crude distillate with a content of 93.8% ethanethiophosphonic acid n-propyl ester chloride are obtained (90.9% of theory) and 150 g of oil as residue, from which, after cooling, another 64 Allow g of crystalline sulfur to be suctioned off.

Fractional distillation of the crude distillate produces 92 g first runnings 1137 g ethanethiophosphonic acid 0-n-propyl ester chloride with a boiling point of 94 ° C 99.4% purity obtained.

Example 5 Preparation of propanthiophosphonic acid O-isopropyl ester chloride 198 g of propane-O-isopropyldithiophosphonic acid (1 mol) in 300 ml of methylene chloride gassed with 107 g of chlorine (45 mol) at below 30 ° C. with stirring.

For this purpose, 198 g propane-O-isopropyldithiophosphonic acid advertise three times alternately with stirring added and 71 g of chlorine (1 mol) gassed in.

A further 198 g of propane-O-isopropyldithiophosphonic acid are then added.

The reaction mixture is worked up as in Examples 1-3.

134 g of first runnings from Kpla 89-94 OC, the 74% main product, are obtained contains and 531 g of propanthiophosphonic acid O-isopropyl ester with a boiling point of 18 94 - 96 0C 95% purity (75.2% of theory in total) 125 g of sulfur and 306 g of bis-propane-o-isopropylthiophosphonyl disulfide.

Example 6 Preparation of isobutane thiophosphonic acid isopropyl ester chloride 212 g of isobutane-O-propyldithiophosphonic acid (1 mol) in 400 ml of methylene chloride are gassed with 107 g of chlorine (1.5 mol) while stirring at 20-30 ° C.

The reaction mixture is then alternated three times with 212 g of isobutane-O-isopropyldithiophosphonic acid each time (1 mol) added and gassed with 71 g of chlorine (1 mol) and finally with more 212 g of isobutane-O-isopropyldithiophosphonic acid are added.

700 g of crude distillate are distilled off from the reaction mixture in vacuo. 465 g of residue remain, from which 95 g of sulfur are isolated after cooling can.

The fractional distillation of the crude distillate results in 36 g forerun vom Kpl2 83-99 OC 643 g of isobutanthiophosphonic acid-O-isopropyl ester chloride vom Kpl8 99 - 101 OC with 95% purity (75.0 ffi of theory).

Claims (2)

Claims: 1. Process for the preparation of thiophosphonic acid-O-ester-- chlorides of the formula I. by reacting the corresponding dithiophosphonic acid ester (II) with chlorine, optionally in an inert solvent, and separating the precipitated sulfur from the reaction product, characterized by the following reaction steps: a) Reaction of the dithiophosphonic acid O-ester (II) with chlorine in an oil ratio of about 1: 1.5 to a mixture of thiophosphonic acid -O-ester chloride (I) and S2C12, b) adding about the same amount of dithiophosphonic acid O-ester (II) to this mixture that was also used in stage a, with a mixture of thiophosphonic acid O-ester chloride (1) , Bis-O-alkylthiophosphonyl disulfide (III): and sulfur is formed, c) filtering off the crystalline sulfur and d) distilling off any inert solvent used and the thiophosphonic acid 0-ester chloride (I) from the bis-0-alkylthiophosphonyl disulfide (III), e) chlorination of the disulfide (III) with about 2 moles of chlorine / mole of III to a mixture of thiophosphonic acid-0-ester chloride (I) and S2Cl2, which f) by reaction with dithiophosphonic acid-0-ester (II) according to step b back into a mixture of (I), ( III) and sulfur is converted or g) is reacted with H2S, the S2Cl2 being converted into S + HCl, after which the thiophosphonic acid 0-ester chloride (I) is distilled off from the sulfur formed. 2. The method according to claim 1, characterized in that n! To all Carries out reaction steps in the temperature range between about 20 and OOC.