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Home , Hexaethyl tetraphosphate, Insecticide, Tetraethyl pyrophosphate, Triethyl phosphate

Patented Oct. 23, 1951 2,572,806

UNITED STATES PATENT OFFICE 2,572,806 MANUEFACTURE OF TETRAETHY, PYROPHOSPAATE John Sterling Harris, Richmond Heights, Mo., assignor to Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application May 1, 1948, Serial No. 24,683 2 Claims, (C. 260-461) 2 This invention relates to compositions con enty known to the art. A still further object of taining increased amounts of tetraethyl pyro this invention is to provide biological toxicant phosphate, and more. particularly to a process compositions containing increased amounts of for the manufacture of tetraethyl . which poSSeSS over Compositions containing tetraethyl pyrophos 5. S00% greater biological activity for the combat phate are widely used as agricultural economic ing and control of pests such as and mites , particularly against many such than do the compositions containing tetraethyl as aphids and against many acarina such as the pyrophosphate which are presently known to red Spider mites, however, such compositions may the art. be used generally against the lower forms of life O In the practice of this invention, the mixtures which, in the past, have been combatted by the of reaction products from the processes of this use of or nicotine salts. Furthermore, invention contain substantially 40%, that is tetraethyl pyrophosphate has been found useful 38-45%, of tetraethyl pyrophosphate as con in the preparation of insectivoricide and rodenti trasted with the processes of the prior art which cide compositions. 5 yielded mixtures of the reaction productS con While the art has disclosed several methods for taining only 10-15% of the tetraethyl pyrophoS the preparation of tetraethyl pyrophosphate, phate. For uses where substantially pure tetra most of these methods are of interest only from ethyl pyrophosphate is required, the tetraethyl a purely academic and theoretical viewpoint. pyrophosphate may be separated from the mix Prior to this...invention, there has not been a prac 20 tures of reaction productS by high Vacuuin frac tical commercial process for the production of tional distillation (below one millimeter of ner tetraethyl pyrophosphate in good yields from cury) or by one of the extraction meth readily available raw materials. It has become ods as are described and claimed in the United known to the art that when oxy States application Serial No. 24,918 filed May 3, chloride is reacted with the neutral triethyl 1948, now. United States Patent No. 2,523,613 of of Ortho- in a mol ratio of about Dvornikoff or patent application Serial No. 24,672, 1:3 at temperatures of about 130° C. to 150° C., filed May 1, 1948, now United States Patent No. While the resulting mixture of reaction products 2,523,243 of Willis. It is evident that when Sub contains predominantly hexaethyl tetraphos stantially pure tetraethyl pyrophosphate is re phate, there is also present in the mixtures of re quired, that the recovery of the tetraethyl pyro action products about 10-12%, and seldom more phosphate from the reaction mixture of this in than 15%, of tetraethyl pyrophosphate. It is vention containing 38-45% of tetraethyl pyro extremely difficult and tedious to concentrate or phosphate is much more efficient and is to be pre Separate the tetraethyl pyrophosphate from the ferred over the recovery of the tetraethyl pyro mixture of reaction products as almost all of these 35 phosphate from the reaction mixtures of the prior reaction products are subject. to hydrolysis when art which contain only 10-15% of tetraethyl pyro in contact with water and when separation is at phosphate. However, the reaction mixtures tempted by fractional distillation, the fractiona themselves from the proceSSes of this invention tion must be carried Out under a vacuum of a may be advantageously and Satisfactorily used fraction of a millimeter of , as decompo 40 as biological toxicants, likewise these reaction Sition of the tetraethyl pyrophosphate takes place mixtures as such may be used to formulate bio at the temperatures required for distillation under logical toxicant compositions without first Sepa a lower vacuum and maintenance of such very rating the tetraethyl pyrophOSphate from the high, vacuums for distillation purposes. is ex reaction mixtures. The mixtures of reaction tremely expensive, and undesirable, in a commer 45 products from the processes of this invention cial process. are over 300% as biologically active against Such It is an object of this invention, therefore, to pests as aphids and mites as are the compositions provide a proceSS for the production of tetraethyl containing only 10-15% of tetraethyl pyrophoS pyrophosphate in Substantially increased yields phate which are presently known to the art. over the yields obtained by the processes, pres 50 I have discovered that tetraethyl pyrophos ently known to the art. A further object is to phate may be obtained in substantially 40% yields provide a process for the production of reaction by the reaction of hexaethyl tetrapolyphosphate Inixtures containing tetraethyl pyrophosphate in With in the mol ratio of Sub substantially increased concentrations over the stantially 1... mol of the hexaethyl tetrapolyphos concentrations obtained from the processes pres 55 phate to 2 mols of the triethyl phosphate. This 2,572,806 3 4. reaction may be carried out within the tempera slowly added, in a drop-wise manner and with ture range of 125° C. to 160° C. However, the stirring, to the triethyl phosphate. After all of optimum yields are obtained when the reaction the phosphorus oxychloride had been added to is carried out at a temperature of Substantially the triethyl phosphate, the temperature Was 145 C. maintained at 150° C. for an additional 2 hour While the highest yields of tetraethyl pyror to finish off the reaction. In addition to the phosphate are obtained when hexaethyl tetra present, quantitative polyphosphate is reacted with triethyl phosphate chemical analysis of the reaction mixture in in the mol ratio of 1 mol of hexaethyl tetra dicated a 10.9% content of tetraethyl pyrophoS polyphosphate to Substantially 2 mols of triethyl O phate. phosphate, yields of substantially 40% tetraethyl Eacample IV pyrophosphate may be obtained when 1.5 to 3 The reaction mixture from Example III was mols of triethyl phosphate are reacted With 1 inol then heated to 135° C. and 121.4 g. (% mol) of hexaethyl tetrapolyphosphate. However, it is of triethyl phosphate was then added to this preferred to hold the nol ratio within the ratio 15 first reaction mixture, with stirring, and at a of 1 mol of hexaethyl tetrapolyphosphate to 1.9 rate so as to maintain a reaction temperature to 2.1 mols of triethyl phosphate. In carrying of about 135° C. After all of the triethyl phos out the process of this invention, the hexaethyi phate had been added, the temperature of the tetrapolyphosphate need not be separated from reaction mixture was increased to 145° C. and the mixtures of reaction products by which the 20 hexaethyltetrapolyphosphate was made. Rather, this temperature was maintained and the stirring the triethyl phosphate may be added to the reac continued for an additional two hours, yielding tion mixtures containing the hexaethyl tetra a second reaction mixture. Quantitative chem polyphosphate in the proper mol proportions and ical analysis of this second reaction mixture the reaction carried out under the described Con 25 indicated a 41.2% content of tetraethyl pyro ditions to obtain reaction mixtures containing phosphate. tetraethyl pyrophosphate in a Substantially 40% Eacample V yield. A portion of the mixture of reaction products The following examples are illustrative of the from Example III containing 41.2% tetraethyl method by which this invention may be prac 30 pyrophosphate was fractionally distilled under ticed, however, it is not intended that this inven a vacuum of 0.6 millimeter of mercury and the tion be limited solely to the processes as set forth substantially pure tetraethyl pyrophosphate re in the following examples: covered. Eacample I Eacample VI 506 g. (1 mol) of hexaethyl tetraphosphate 546.6 g. of triethyl phosphate Were placed in were slowly warmed to 135° C. in a glass re a glass reaction vessel equipped with reflux con action vessel equipped with a reflux condenser denser. The triethyl phosphate was warmed to and 364.4 g. (2 mols) of triethyl phosphate Were 130° C., at atmospheric , and 1434 g. of gradually added, With stirring, to the Warned 40 phosphorus oxychloride (a mol ratio of 3:1) Were hexaethyl tetraphosphate at such a rate So as gradually added, with stirring, to the warmed to maintain a reaction temperature of about 135° triethyl phosphate at such a rate So as to main C. After all of the triethyl phosphate had been tain a reaction temperature of about 130° C. added to the hexaethyl tetraphosphate, the re which required about two hours. After all of the action mixture was then heated to about 145° C. phosphorus oxychloride had been added to the and thereafter maintained at 145° C. for an triethyl phosphate, the reaction mixture WaS additional two hours during which time the re then slowly heated to 145° C. Over a period of action maSS Was continuously stirred. Quantita one hour and thereafter maintained at 145” C. tive chemical analysis of the reaction mixture for an additional hour. Quantitative chemical indicated that the reaction mixture contained analysis of this reaction mixture indicated a 40.5% tetraethyl pyrophosphate, and biological 15.0% content of tetraethyl pyrophosphate. aSSay of the reaction mixture indicated that the Eacample VII biological activity of this reaction mixture was inore than 300% greater than the biological Thereafter, the reaction mixture from Example activity of compositions containing hexaethyl VI was warmed to 130° C. and 364.4 g. (2.0 mols) tetrapolyphosphate or the compositions contain of triethyl phosphate were slowly added to the reaction mixture at such a rate so as to main ing 10-15% tetraethyl pyrophosphate which are tain a reaction temperature of about 130 C. known to the art. After all of the triethyl phosphate had been Eacample II added, the temperature was raised to 145 C. The mixture of reaction products from Ex- { over a period of one hour and thereafter, while ample I, containing 40.5% tetraethyl pyrophos the stirring of the reaction mixture WaS COn phate Was fractionally distilled under a very high tinued, the reaction mixture was held at 145 Vacuum (0.5 millimeter of mercury) and substan C. for an additional two hours. Quantitative tially pure tetraethyl pyrophosphate recovered. chemical analysis of the reaction mixture indi Eacample III (5 cated a 41.7% content of tetraethyl pyrophos phate. U. S. Patent No. 2,336,302 to Schrader relates to the production of hexaesters of tetraphos Eacample VIII phoric acid. U. S. Patent No. 2,402,703 to Woodstock also A reaction mixture containing substantially 70 relates to the production of hexaesters of tetra hexaethyl tetraphosphate was prepared accord phosphoric acid. ing to the teachings of that patent: - A reaction mixture containing substantially 182 g. of triethyl phosphate were heated, with hexaethyl tetraphosphate was prepared accord stirring and under reflux, to a temperature of ing to the teachings of that patent: 150° C. 53 g. of phosphorus oxychloride were 75 156 g. of P2O5 were slowly added to and reacted 2,572,806 5 6 With 400 g. of triethyl phosphate at 50° C. in a which has been sprayed with Cooled glass: reaction:vessel. The:P2O53 was added the reaction mixture containing, the tetraethyl at Such a rate. So as to maintain a reaction tems. pyrophosphate:is then tumbled in, a rotary drum perature, of about 50° C. Thereafter the mix until the dust is well-mixed. ture: Was stirred for an additional two. hours to In place of the diatomaceous earth, talc or give a first, reaction. product, which, according pyrophyllite may be used as the inert diluent or to U. S. Patent. No. 2,402.703, is predominantly Solid carrier for the tetraethyl pyrophosphate. hexaethyl tetraphosphate. A more-readily Wettable powder may be prepared This first reaction mixture containing, pre by mixing 1% of a Wetting agent. With the dia dominantly hexaethyl tetraphosphate is: then tomaceous earth, or other carrier or inert diluent, slowly heated, with stirring;...to 120° C.in a glass and Subsequently spraying the mixture of carrier reaction vessel and an additional 400 g. of tri and Wetting agent with a reaction mixture or a ethylphosphate are slowly; added, while the stir Solvent solution of a reaction mixture containing ring...is continued and the temperature: is main tetraethylpyrophosphate, and then tumbling the tained at 120° C. Thereafter, the temperature 5 sprayed mixture in a rotary drum until the dust is increased to 145° C. and the reaction mixture is Wei-mixed. is: continuously stirred, while the temperature is In some instances, it is more desirable to have maintained at 145° C. for an additional two hours, a liquid mixture, of tetraethyl pyrophosphate and yielding a second reaction mixture: containing a liquid carrier, which is Suitable for Spraying. Substantially 40% tetraethyl pyrophosphate. Such a liquid mixture may be prepared by dis solving about one part of a Wetting agent and Eacample IX one part of one of the mixtures of reaction prod ucts, such as was prepared in Example I, in 1600 A portion of the mixture of reaction products parts of water. While water is the most con from Example V containing. 41.7% tetraethyl ; veniently used liquid carrier, other Suitable liquid pyrophosphate was fractionally distilled under a carriers are aromatic Such as benzene, vacuum of 0.4 millimeter of mercury and Sub toluene, Xylene and . stantially pure tetraethyl pyrophosphate recov Suitable wetting agents for use in liquid mix ered. tures.or for the preparation of the Wettable dustS, In the above examples, the hexaethyl tetra as described above, may be the alkali metal Salts phosphate, or the reaction mixture containing of a mono-, di- or tri-sulfonate or sodium dodecyl hexaethyltetraphosphate, may have been main benzene sulfonate. Other types of Sulfated and tained at a temperature with the range of 120° C. sulfonated wetting agents which are also Suitable to 150° C. during the addition of the triethyl are the sulfo-succinic acid dialkyl Such phosphate, however, it is preferred to maintain as sodium dioctyl sulfo-Succinate and the decyl the temperature at 120° C. to 130° C. during the or dodecyl sodium sulfates. Also suitable are the addition of the triethyl phosphate. The tem poly-ethylene oxide condensation products of perature during the “finishing period,' that is alkyl substituted phenols (wherein the alkyl Sub the period following the completed addition of stituent contains 4 to 18 carbon atoms) with 8 to the triethyl phosphate to the hexaethyl tetra- is 25 mols of ethylene oxide, for example the con phosphate or reaction mixture containing the densation product of 1 mol of octyl phenol with hexaethyl tetraphOSphate, may be from 130° C. 10 to 12 mols of ethylene oxide. to 160° C. for a “finishing period' of 1 to 5 hours, The mixtures of reaction products containing the longer periods of time being required at the substantially 40% tetraethyl pyrophosphate of lower temperatures of about 130 C., and the use 45 this invention may also be formulated into con of the higher temperatures of 150° C. to 160° C. centrates for forming oil-in-water emulsions for during the finishing period being limited by a use as insecticidal compositions. A Self-dispers resulting darkening of the product due to de ing, water dispersible concentrate for forming composition. The preferred finishing conditions stable oil-in-water emulsions may be prepared by are a temperature of about 142° C. and a period 50 preparing a mixture containing 85.0% xylene, of 2 to 3 hours. 5.0% dodecylbenzene sodium sulfonate, 5.0% of If it is desired, the tetraethyl pyrophosphate, the condensation product of 1 mol of octyl phenol Which is produced in accordance With the direc and 10-12 mols of ethylene oxide and 5% of the tions of the above examples, may be separated mixture of reaction products containing substan from the reaction mixtures by fractional distilla 55 tially 40% tetraethyl pyrophosphate Such as WaS tion, or otherWise, or the mixtures of reaction described under Example I in accordance with the products containing the tetraethyl pyrophosphate practice of this invention. The above concen may be used as Such in the formulation of com trate may be added to water in almost any pro positions for use as economic poisons. These portion desired for the formation of a permanent mixtures of reaction products, containing sub 60 oil-in-Water emulsion for use as an insecticidal Stantially 40% tetraethyl pyrophosphate may be composition against aphids and red spider mites. formulated into either liquid or powder types of The term biological assay, often times referred compositions of increased biological activity. to as the bioassay, of a composition is an indica For example, one of the above mixtures of reac tion of the biological activity of a particular in tion products containing Substantially 40% tetra 65 seaticidal composition. Herein, in this descrip ethyl pyrophosphate may be formulated by Spray tion and the claims, the term “,' When used ing the Said mixture onto finely ground diatona as “insect' or ",' is used in the com ceous earth. In the control of aphids and mites, In On or popular Sense to include the allied classes a dust containing about 5% of tetraethyl pyro of Silch as the , and the phosphate is usually Satisfactory and such a dust 70 Airachinida. Biological aSSays were run on the may be prepared by spraying 97.5 pounds of finely nixture of reaction products which were derived ground diatonaceous earth with 12.5 pounds of a in accordance With the procedures described in mixture of reaction products such as was de Examples IV and WII which are representative Scribed in Example I, and which contains Sub of the present invention and on the material pre stantially 40% of tetraethyl pyrophosphate. The pared in accordance With Examples III and VI 2,572,806 7 8 which are representative of the material pre I claim: pared in accordance With the prior art. 1. In a process for the manufacture of tetra The biological assays were carried out in the ethyl pyrophosphate, the step comprising react following manner: ing together at temperatures between the limits In each test, twenty third instar milk-weed of 125° C. and 160° C. and for a period of at least bugs were placed on a filter paper in petri dishes one hour substantially 2 molecular proportions of and exposed in a standard laboratory Spraying triethyl phosphate and the reaction product ob tower to a constant volume of atomized mist of the tained by reacting at temperatures between the toxicant composition being tested. The toxicant limits of 125° C. and 150° C. 1 molecular propor is diluted to the desired concentration with Water 10 tion of phosphorus Oxychloride and substantially containing a Wetting agent in the ratio of one 3 molecular proportions of triethyl phosphate. part of the wetting agent to 1600 parts of Water. 2. In a process for the manufacture of tetra After exposure, the bugs are transferred to clean ethyl pyrophosphate, the steps comprising adding dishes and counts are made after a lapse of a at temperatures between the limits of 125° C. and period of ten minutes. The tests are repeated 5 135° C. substantially 2 molecular proportions of until the minimum concentration of toxicant has triethyl phosphate to a reaction product obtained been determined which will consistently produce by reacting together at temperatures between the a kill of 95% of the bugs. The minimum Con limits of 125° C. and 150° C. 1 molecular propor centration is referred to as the Lld 95 value. tion of phosphorus oxychloride and Substantially When tested in accordance with the above pro 20 3 molecular proportions of triethyl phosphate, cedure, the following LiD 95 values were deter and thereafter maintaining the temperature of mined for the mixtures of reaction products the reaction at 140° C. to 155° C. for 1 to 5 hours. which were prepared as described in Examples JOHN STERLING HARRIS. III, IV, VI, and VII: Percent 25 REFERENCES CITED LD 95 Example VII------0.05 The following references are of record in the LD 95 Example IV------0.06 file of this patent: I.D 95 Example VI------0.18 UNITED STATES PATENTS LD 95 Example III------0.26 30 Number Name Date Bearing in mind that Examples IV and VII 2,336,302 Schrader ------Dec. 7, 1943 are representative of the compositions produced 2,402,703 Woodstock ------June 25, 1946 in accordance with this invention, and Examples III and VI are representative of the prior art, 2,462,057 Adler ------Feb. 22, 1949 it is readily apparent that the compositions of 2,510,033 Kyrides ------May 20, 1950 this invention have more than 300% greater bio 35 OTHER REFERENCES logical activity than those compositions of the Cavalier, “Comptes rendus,' vol. 142 (1906), prior art. pp. 885 to 887. Having described and Set forth my invention Hall et al., “Ind. & Eng. Chem.' vol. 40 (April in detail and having given examples showing ma 1948), pp. 694 to 699. terial improvement of my process over the proc 40 esses of the prior art,