DE867994C - Process for the production of organic thiophosphoric acid esters - Google Patents

Description

Process for the preparation of organic thiophosphoric acid esters The invention relates to an improved, economically feasible process for the preparation of thiophosphoric acid-0, 0-dialkyl-Op-nitrophenyl esters of the general formula in which R denotes an alkyl radical which contains at least 1 and at most 8 carbon atoms.

Organic thiophosphoric acid esters, especially thiophosphoric acid-O, 0-diethyl-O-p-nitrophenyl ester, are of particular importance as insecticides. So far, such esters have been prepared by adding 2 moles of a sodium alcoholate with i mole of Tfiiophosphorsäurechlorid to the reaction, the corresponding Thiophosphoric acid chloride 0, 0-dialkyl ester is formed. This reaction product was then 1 mole of anhydrous sodium p-nitrophenolate in anhydrous monochlorobenzene suspended, added. This particular process gives only low yields and is extremely exposed to coincidences. To the suspension of sodium p-nitrophenolate in monochlorobenzene, it is necessary to convert the p-nitrophenol to monochlorobenzene add, neutralize with a sodium hydroxide solution and then monochlorobenzene and removing water by azeotropic distillation causing dehydration. During the distillation, the sodium p-nitrophenolate shows a tendency to tend to lump and overheat locally. This local overheating sometimes occurs Cause the sodium p-nitrophenolate to decompose violently. This will the technical production of this suspension exposed to coincidences and made more difficult.

The inventive method, the shortcomings with the Use of alkali p-nitrophenolate linked, reduced to a minimum, and these esters are obtained in high yield.

According to the present invention, the thiophosphoric acid chloride-0, 0-dialkyl ester prepared in the usual way and this then with Alkalip-nitrophenolate reacted in an alcoholic medium. This reaction can be due to various factors Because of being brought about. To the thiophosphoric acid chloride 0, 0-dialkyl ester, the has been prepared in the usual way, p-nitrophenol can be added and afterwards an alcoholic solution of an alkali metal alcoholate, with an alkali metal p-nitrophenolate immediately is formed, which in the formation with the thiophosphoric acid chloride 0, _ 0-dialkyl ester reacts and the 0, 0-dialkyl-O-p-nitrophenyl ester of thiophosphoric acid in high Yield supplies. The reaction can also be carried out so that the thiophosphoric acid chloride-0, 0-dialkyl ester with alkali metal pnitrophenolate in an alcoholic medium for implementation is brought. Example r To 37.73 kg of thiophosphoric acid chloride were within of 2 or 3 hours, 159.13 kg of an approximately 20% solution of sodium ethylate in Ethyl alcohol was added, the temperature being kept below 10 °. This Mixture, then 3o.96 kg of p-nitrophenol are added, and the resulting Solution are then 75.77 kg of an approximately 20% solution within 2 hours of sodium ethylate in ethyl alcohol added, the temperature below io ° is held. This reaction mixture is stirred for about 18 hours, after which the Reaction has come to an end.

A larger part of ethyl alcohol was taking from the reaction mixture Stirring distilled off at atmospheric pressure. The reaction mixture were then 213.38 L of water were added to dissolve the sodium chloride and to remove the 0, 0-diethyl-O-p-nitrophenylthiophosphate separated from the remaining alcohol. The remaining mixture was filtered through a filter -pumped. The filtrate then separated into an upper, aqueous layer consisting of the lower layer of the 0, 0-diethyl-O-p-nitrophenylthiophosphate is decanted off became.

The lower layer was washed twice, with 68.1 liters of one 3% solution of sodium carbonate was stirred, whereupon it was washed with 68.1 liters of water became. The lower layer was then subjected to steam distillation, to remove triethyl thiophosphate. The distillation continued for so long until no more oil could be detected in the distillate.

The aqueous layer was removed from the cooled material in the still decanted off. The organic layer was heated to 100 ° for half an hour dried at 100 mm vacuum. The end product, 0, 0-diethyl-0-p-nitrophenylthiophosphate was obtained in a total yield of -7o0 / "based on thiophosphoric acid chloride.

The 0, 0-diethyl-O-p-nitrophenylthiophosphate obtained in this way is a dark brown, oily liquid with a freezing point of 3, q. ° _, a specific gravity of 1.2651 at 25 ° and a refraction exponent n 'of 1,537 has.

The quantities and temperatures given in Example i are intended does not express the scope of the new process of this invention solely to this Limit the quantities and temperatures listed. So you can z. B. preferably a ratio of 2.0 to 2.2 moles of sodium alcoholate of an aliphatic alcohol, which contains at least 1 and at most 8 carbon atoms, per 1 mol of thiophosphoric acid chloride adhere to to produce thiophosphoric acid chloride 0, 0-dialkyl ester, but can also use larger or smaller amounts of sodium alcoholate. But if more than 2.2 moles of sodium alcoholate are used, larger amounts of trialkyl thiophosphate are used and if less than 2 moles of sodium alcoholate are used larger amounts of thiophosphoric acid chloride-0-alkyl ester are formed.

The concentration of the sodium ethylate in the ethyl alcohol can also be used can be varied considerably. If the concentration is increased noticeably above 20%, so the sodium ethylate tends to crystallize out of the alcoholic solution. If the concentration is reduced to below 20%, the reaction can still occur but the amount of solution increases.

The reactions are best in the temperature range of about -io ° executed up to about + io °. Temperatures that exceed + io ° favor the formation of trialkyl thiophosphate. If the temperature is lowered below -io °, will the speed of reaction necessarily slower. In the reaction between Thiophosphoric acid chloride 0, 0-dialkyl ester and alkali p-nitrophenolate in alcoholic Medium must be the temperature within the preferably applicable limits of about -io ° to about + io ° are only paused during the time in which the alkali p-nitrophenolate is used in alcoholic solution to the thiophosphoric acid chloride 0, 0-dialkyl ester. To The addition of the reagents can reduce the temperature even up to the boiling point of the less volatile component can be increased.

The substances that react with one another, namely thiophosphoric acid chloride, the alcoholic solution of sodium alcoholate and p-nitrophenol, should be substantially anhydrous, with a moisture content of preferably less than 0.3 percent by weight. If conditions are maintained which ensure anhydrous operation, it is possible to recover essentially anhydrous alcohol from the reaction, which can be recycled without further dehydration and used to prepare additional quantities of alcoholic solutions of sodium alcoholate. In order to work economically, however, it is not absolutely necessary that approximately anhydrous conditions are maintained during the reaction between thiophosphoric acid chloride-0, 0-dialkyl ester and the sodium p-nitrophenolate in an alcoholic medium. In this last phase of the reaction it is possible to use an alcoholic medium which contains about 20 percent by weight of water. Furthermore, in this last phase, the alkali p-nitrophenolate can be prepared in an alcoholic medium by allowing p-nitrophenol to react with sodium carbonate, potassium hydroxide, potassium carbonate or sodium hydroxide in an alcoholic medium, an aqueous alcoholic solution or suspension of alkali p- nitrophenolate is formed. If such a manufacturing process is used for the alcoholic solution of the alkali p-nitrophenolate, the recovery of substantial amounts of anhydrous alcohol from the reaction is not feasible. In such a case, the recovered alcohol must therefore be dehydrated before additional amounts of anhydrous alcoholic solution of sodium alcoholate can be prepared and used to prepare the thiophosphoric acid chloride 0, 0-dialkyl ester, since this reaction works best under substantially anhydrous conditions according to the one here procedure described is carried out.

While it is economically more affordable, the same sodium alcoholate solution with the corresponding alcohol both in the reaction to form thiophosphoric acid chloride-0, 0-dialkyl ester and also in the final reaction to the formation of 0, 0-dialkyl-O-p-nitrophenylthiophosphate can use the solution of a different alcohol and a different one Sodium alcoholate can be used in the latter reaction. So would have in education of sodium p-nitrophenolate in situ according to Example i, a solution of sodium butoxide can be used in butyl alcohol. Provided the recovered alcohol of the latter Reaction is essentially anhydrous and is added to the circuit to obtain additional Amounts of sodium all: oholate can be recycled, it is preferable in the case of the latter reaction to use the same alcohol and the same sodium alcoholate, how they were used in the first reaction.

The order in which the reacting substances in the above Step of the new procedure is admitted to a certain extent of Meaning. It is preferable that the reacting substances are added so that not a mixture of thiophosphoric acid chloride-O, 0-dialkyl ester with a alcoholic solution of the sodium alcoholate is formed without p-nitrophenol in such an amount would be present that the mole fraction of p-nitrophenol present corresponds to the mole fraction corresponds to or exceeds the sodium alcoholate contained in the mixture. While so in example i the preferred embodiment for the execution the reaction is described, namely the formation of p-nitrophenolate in situ, so the invention is not intended to be limited to this embodiment alone. It has been found that products are obtained in equally good yield and purity can if you use p-nitrophenol and the alcoholic solution of sodium alcoholate at the same time the thiophosphoric acid chloride 0, 0-dialkyl ester added. Furthermore can the alcoholic solution of sodium p-nitrophenolate must be prepared separately in such a way that one molar proportion of p-nitrophenol is approximately one molar proportion of sodium alcoholate is added in alcoholic solution and that the sodium p-nitrophenolate thus formed, which is contained in an alcoholic medium, with thiophosphoric acid chloride-0, O-dialkyl ester reacts in such a way that either the alcoholic solution of the sodium p-nitrophenolate is added to the thiophosphoric acid chloride 0, 0-dialkyl ester, or that one thiophosphoric acid chloride 0, 0-dialkyl ester of the alcoholic solution of sodium p-nitrophenolate is added.

It is preferable to use p-nitrophenol in the proportion that approximately one mole fraction one mole fraction of that originally used Thiophosphoric acid chloride corresponds. However, this proportion can be up to a certain point Degrees can be varied. If the proportion of p-nitrophenol is reduced significantly, so the desired response will not be complete. If you increase the amount of p-nitrophenol excessive amounts of p-nitrophenol or sodium p-nitrophenolate become essential not included in the reaction.

It is therefore preferable that sodium alkoliolate in the molar ratio i : i applied to the amount of p-nitrophenol used. However can this proportion can be varied to a certain extent. When the amount of sodium alcoholate goes significantly beyond the proportionate proportion that is preferably to be applied, in this way excessive amounts of 0, O-trialkyl thiophosphate are formed which reduce the yield affect the end product. If much smaller amounts are used, the yield of the end product falls, since not all thiophosphoric acid chloride 0, 0-dialkyl ester Has been included in the reaction to produce 0, O-diethyl-0-p-nitrophenyl thiophosphate to build. Example 2 To 1 mole of thiophosphoric acid chloride in a suitable reaction vessel In 2 hours, 2.05 moles of sodium methylate were obtained as a?, o% solution in methyl alcohol present, added, and the temperature was kept below 10 °. To this Mixture was added 1 mole of p-nitrophenol, and to the resulting solution were then in 1 hour 1 mole of sodium methylate in 2o% methyl alcoholic solution added, the temperature being kept below 10 °. The stirring continued for 16 Hours after which time the reaction was over.

Approximately 80 per cent of the excess methyl alcohol was removed from the stirred reaction mixture distilled off at atmospheric pressure. The residue was then washed with water, filtered and decanted. The bottom layer was washed twice with a 311 / o solution of sodium carbonate, whereupon a Wash with water followed. the moist bottom layer became like this Long subjected to steam distillation until there is no more oil with the distillate passed over. The aqueous layer was decanted from the organic material, and that finished product 0, 0-dimethyl-0-p-nitrophenyl thiophosphate was made by heating it up == 0 ° dried at 100 mm vacuum for 1/2 hour.

Example 3 To 1 mole of thiophosphoric acid chloride in a suitable reaction vessel 2.2 moles of sodium butoxide were obtained as a 20% solution of sodium butoxide in butanol present, admitted. The temperature was increased during the addition period, which was about 3 Lasted hours; kept below = o °. This reaction mass became 1 mole anhydrous Sodium p-nitrophenolate as a 20% solution, dissolved in butyl alcohol, was added. During this addition period, which extended over a period of 2 hours, the temperature was kept below 0 °, the mixture was stirred for 16 hours, after which the reaction was complete.

The excess butyl alcohol was taken from the mixture at atmospheric Distilled pressure. The resulting reaction mass was still in agreement with the procedural measures as set out in Example 2, cleaned. The resulting product was 0, 0-dibutyl-0-p-nitrophenyl thiophosphate. The product is a light brown liquid with a freezing point below -25 °.

Example q.

i mole of thiophosphoric acid chloride were 2.1 moles within 3 hours Sodium 2-ethylhexylate, which is obtained as a 10% solution of sodium 2-ethylhexylate in 2-ethylhexanol is present, added, and a temperature below = 0 ° was maintained. One mole of p-nitrophenol was added to this mixture and then within 2 hours, 1 mole of sodium 2-ethylhexylate, as a 10% solution in 2-ethylhexanol Template. The mixture was stirred for 16 hours at which time the reaction was complete was.

Excess 2 ethylhexanol was reduced by distillation under reduced pressure Pressure removed. The reaction mass was then mixed with water and a 3% sodium carbonate solution washed. The moist product was then subjected to steam distillation. The aqueous layer and the organic layer were decanted from the cooled material Layer dried by heating to == o ° at a vacuum of 100 mm for 1/2 hour. The end product was 0, 0-di-2-ethylhexyl-O-p-nitrophenyl thiophosphate. Example 5 To 37.73 kg of thiophosphoric acid chloride within 2 to 3 hours = 59.13 kg of an approximately 20% solution of sodium ethylate in ethyl alcohol was added, and a temperature below = 0 ° was maintained, this mixture Then 3o, 96 kg of p-nitrophenol and 8.9o kg of sodium hydroxide in flakes were added. The reaction mass was kept moving until the reaction was complete.

Much of the ethyl alcohol in the mix became from this distilled off at atmospheric pressure. Then the reaction mixture became water added to dissolve sodium chloride and add the thiophosphate ester from the alcohol separate. After filtration, two layers formed in the filtrate. Of this The upper, aqueous layer was separated from the lower layer, which consisted of 0, 0-diethyl-0-p-nitrophenylthiophosphate consists, separated by decanting.

The lower layer was covered with a 30% sodium carbonate solution and water washed. The moist lower layer was then to 0, 0-triethyl thiophosphate to remove, subjected to steam distillation. The wet ester was worked up and dried by heating at about == o ° under vacuum. Here became pure 0, 0-diethyl-O-pnitrophenylthiophosphate in excellent yield won.

Example 6 Over a period of several hours, 159 kg an approximately 2oo / o solution of sodium ethylate in ethyl alcohol at 37.73 kg Thiophosphoric acid chloride added, a temperature of a little below = 0 ° maintained became. To this mixture were then added 3o.9o kg of p-nitrophenol and 23.61 kg of sodium carbonate added at a temperature of a little below = o °. After all reacting substances were added, the temperature was increased to about 80 ° and it was until the Reaction was complete, mechanically stirred.

The excess ethyl alcohol was reduced by distillation Pressure removed. The reaction mass was washed with water and a dilute sodium carbonate solution washed. The moist product was then subjected to steam distillation, to remove 0, O-triethyl thiophosphate. The organic layer was then through Heat under vacuum to about == o ° dried, giving an excellent yield obtained from 0, 0-diethyl-0-pnitrophenylthiophosphate:

Claims (5)

PATENT CLAIMS: r. Process for the preparation of organic thiophosphoric acid esters of the general formula in which R denotes an alkyl radical with at least 1 and at most 8 carbon atoms, characterized in that a thiophosphoric acid chloride 0, 0-dialkyl ester, in which the alkyl radicals contain at least 1 and at most 8 carbon atoms, with an approximately equimolecular amount of an alkali metal p-nitrophenolate is implemented in the alcoholic medium. 2. Modification of the method according to claim i, characterized in that that one mole of a thiophosphoric acid chloride 0, 0-dialkyl ester, its Alkyl groups contain at least i and at most 8 carbon atoms, with approximately equimolecular Reacts proportions of an alkali p-nitrophenolate, preferably by reaction is obtained from p-nitrophenol with a sodium alcoholate in alcoholic solution, wherein the alkyl groups of the sodium alcoholate have at least 1 and at most 8 carbon atoms contain. 3. Modification of the method according to claim i, characterized in that that i mole of a thiophosphoric acid chloride 0, 0-dialkyl ester, its alkyl groups contain at least 1 and at most 8 carbon atoms, reacted with about 1 mole of a p-nitrophenol is and at the same time or subsequently added about 1 mole of sodium alcoholate where the alkyl groups of the alcoholate have at least 1 and at most 8 carbon atoms contained and this is dissolved in an alcoholic agent. q .. amendment of the method according to claim 2, characterized in that i mole of thiophosphoric acid chloride with about a mole of a sodium alcoholate, the alkyl radical of which is at least i and at most Contains 8 carbon atoms, is converted in alcoholic solution and then the reaction mixture obtained in this way with about 1 mole of an alkali metal nitrophenolate in the alcoholic Medium is further condensed. 5. The method according to claim q., Characterized in that that the reaction temperatures in the reaction stages are each about -io to + io ° be.