2,899,446 Unite States Patented Aug. 11, 1959 1 2 position of the epoxide or acts as a catalyst for the de struction of the linkage by acid which may be present 2,899,446 or acts in some other manner. However, it is known that IMPROVEMENT IN THE PROCESS or PREPARING this unexpected reaction causes serious di?iculty in both ENDRIN FROM ISODRIN the production of endrin andin its utility once it has been prepared. During the reaction performed in the Daniel R. Marks, Memphis, Tenn., assignor to Velsidol presence of metallic contamination several undesirable Chemical Corporation, Chicago, 111., a corporation of by-products will be produced. While as previously indi Illinois cated, their exact structures are not known, the prepon derance thereof are believed to be ketones, the presence No Drawing. Application August 14, 1956 10 Serial No. ‘603,871 of which is indicated by infrared analysis of the product. This assumed rearrangement of the desired epoxide to 3 Claims. (Cl. 260——348.'5)' the undesired ketone during the reaction of isodrin and peracetic acid could involve the rearrangement of the epoxy linkage to a (3:0 linkage and a shifting of a hy This invention relates to the preparation of a stable 15 halogenated organic composition. In particular this in drogen atom to vform an analogue of endrin. However, vention relates to stable l,2,3,4,10,lO-hexachloro-6,7 other ketones may be formed therein caused perhaps by epoxy-1,4,4a,5,6,7,8,8a - octahydro - l,4,5,8 - dimethano the breaking up of the cyclic rings. In addition, still naphthalene having the structural formula: other compounds may result from the effect of the metal lic contamination. 11 H 01 20 The formation of these compositions is undesirable for a multitude of reasons, including larger raw material costs 0 H 1 Ha s01Glzl to produce a given quantity, an impure product of ques H -01 tionable value, the possible necessity of additional puri? H 25 cation equipment, and a general hindrance in the produc H tion and use of this insecticidally active compound. and an improvement in the preparation thereof. Herein In commercial preparation there are inherently pres after this compound will be referred to as endrin, its gen ent from numerous sources varying amounts of metallic eric name. contamination. This is exempli?ed by the fact that C.P. US. Patent 2,676,132 describes the preparation of en_ 30 (chemically pure) grade glacial acetic acid, a solvent drin and claims it as a new composition of matter. for said reaction, has been found to contain 0.2 ppm. Endrin has rapidly gained recognition as an extremely (parts per million) iron, while C.P. anhydrous sodium valuable agricultural chemical being e?ective against acetate usable in the reaction as a buffering agent con numerous undesirable plant pests which are detrimental tains approximately 1 ppm. Other reactants often con to such crops as cotton, cabbage, sugar beet, tobacco, tain small quantities of these harmful metals, as does nor‘ corn, and the like. The list of insects against which it mal plant water. Also, such metal is often incorporated affords superior protection includes virtually every major into the system from the equipment or it may be present insect pest. Further, its recognition as a superior insecti in the solvent. Then, too, there is a tendency for this cide is not limited to the United States, but on the con metal contamination to build up, that is, for only a part trary is worldwide. 40 of it to be removed with a batch so that after a few Consequently, it is desirable that an ef?cient method batches the concentration becomes considerably increased. for the preparation of this valuable composition be readi It is not unusual for the build-up of iron, nickel, etc., to ly available and of even further importance that the sta reach as high as 40 p.p.m., and it can possibly go higher. bility of the endrin product be such that one can obtain Since it has been found that concentrations as low as 0.16 the maximum bene?t of its valuable properties. ppm. will adversely affect the purity and consequently ' It is therefore an object of the present invention to 45 the value of the product, the scope of the problem is prepare endrin which is relatively stable. readily ascertainable. In the absence of such contami It is another object of the present invention to improve nation, endrin with a minimum purity of 95% is ob existing processes for the preparation of endrin. tainable without recrystallization or other puri?cation Still other objects of the present invention will become means. On the contrary, in the presence of the afore apparent from the ensuing description. 50 mentioned metallic contamination, the purity, of the en' ’ Example IV of US. Patent 2,676,132 describes a drin product will be low, and an inferior product as com process for the preparation of endrin by the reaction of pared to the 95-100% pure endrin. ' , f , beta -. 1,2,3,4,10,10 - hexachloro - 1,4,4a,5,8,8a - hexahy Since it takes a relatively minute amount of con dro - l,4,5,8 - dimethanonaphthalene, hereinafter referred tamination to cause these adverse effects and since there to as isodrin which is its generic name, and peracetic acid. 55 are a multitude of sources for said metals, it is apparent As describ'ed‘in that patent, this process is a satisfactory that it is impractical and uneconomical to keep this method for the preparation of this highly valuable com low concentration of metal out of the reaction mixture. pound. If performed in the absence of impurities and Thus, it is extremely desirable to otherwise preventthese under optimum conditions, high yields of a relatively detrimental consequences caused by metallic contamina pure product (95—100%) may be obtained. 60 tion and this is unexpectedly accomplished. by the meth-v However, when this reaction is run in the presence of 0d herein described. metallic contamination, serious difficulties are encountered While the metallic contamination which actuates the.; in, thatseveral undesired side products are produced, ‘the aforementioned undesired change in product probably. product is of low purity and it is rendered somewhat un is not limited to any speci?c metal or group of metals, stable by virtue of the large percentage of impurities. 65 iron and nickel are the most common metals present While neither the mechanism for this breakdown of the in commercial preparations. Thus, it has been found endrin product nor the identity of all of the products that the presence of these metals during the preparation formed therefrom is known, it is believed to involve of endrin leads to undesired lay-products and further to several complex structural modi?cations culminating in a less satisfactory product. This product as compared a breaking of the vital epoxy linkage. It is also not cer 70 to technical endrin commercially produced in a metal tain Whether the metal directly attributes to this decom free state is relatively unstable. It also contains color 2,899,446

bodies, ‘while the aforementioned product not adversely was heated to 90° C. and then cooled at room tem affected by metal in its production is white in color. perature. When cooled‘ the product was ?ltered, washed, The instability of this product creates some problems. dried and analyzed by infrared. The nickel or iron For example, this metal containingjendrin has a meltj added to the runs listed in Table I was added in the ing point much lowerjthan pure endrin (2451” C.), and form of the corresponding sulphate. The material in since it is a'rnixed melting pointwill vary with the actual the product which is noten‘drin (see column percent amount‘ of '_by-pr'oduct formed, metal content, and the endrin) is, unreacted starting, material or undesired» by; like. This low melting point creates problems in drying products. I > the product and also in grinding, a standard operation ‘in As can be readily ascertained from the foregoing table, the'preparation of commercial‘ dry insecticide formula 10 that-While the presence of DPA in: even‘ low concentra~ tions. Further, the presence of these undesired com tions is highly bene?cial, a— minimum DPA-:metal molar pounds lowers the amount of insecticidally active in ratio of 1:1 is of even further advantage, and DPAzmetal gredients in the product making it necessary to use ratio of 2:1 or higher is- preferred. higher concentration formulations,‘ which may be im Thus from the table it is seen.} that mole ratios of DPA practical‘ due to economic considerations or due to physi 15 to metal above 4 produced a high grade product con cal limitations, such as the inability of the carrier to taining over 95% endrin. When‘ this'mole ratio is be adsorb said composition. ‘ ‘ ‘ tween about 1 and 4 the concentration of endrin in the Unexpectedly, it has‘ been found that this vexing product drops to between. 90 and 95% below a mole problem can-be ‘solved by the utilization of dipicolinic ratio of DPA to metal of about 1, the concentration of acid in the production of ’ endrin. Dipicolinic acid, 20 ?nal product is still lower, dropping to below 80. which hereinafter willbe referred to as DPA,’ is meta The mode of addition of the DPA to the reaction zone 2,6-pyridine dicanboxylic acid. may be performed by any of the methods known to the As previously indicated, I have performed many art for the addition of solid matter such as by the use experiments on the preparation of endrin from isodrin of conveyor ‘belts, manual. addition, feed tanks, etc. It inthe presence of varying ratios of nickel or iron and 25 also may ‘be added ‘in its melted state although this is not DPA. In these laboratory experiments iron and nickel, a preferred method. Actually the amount of DPA added inherently present in commercial operations, were added on a percentage basis ‘in ‘most cases is very small, and in varying quantities so as to simulate commercial con hence addition thereof to the reaction zone does not con ditions. The metal content thus was that added plus the stitute a problem. If desired, the DPA may be added con small quantity already present from the reagent grade 30 currently with the isodrin .or one of the other charged. chemicals, etc. Glass equipment was utilized through reactants. Also, but not'as an alternative to DPA being out all of these experimental runs. Table I shows the present during reaction, the DPA may be added to the results of these reactions in ‘all of which the following ?nal product after completion of the reaction and subse procedure was employed: . quent puri?cation. This would: prevent any degradation 112.8 grams of isodrin, 118.8 grams of acetic acid 35 of the endrin due to metallic contamination during for and 2.3 grams of anhydrous‘sodium acetate (buffering mulation and ?nal use of the endrin. A standard blender agent) were charged to a 500 ml. three-necked glass for the mixing of solid materials may be used to incor ?ask equipped with stirrer, thermometer and addition porate thisv unique stabilizer with the endrin. While the funnel. This mixture was then heated to 60° C. at amount of DPA necessary in such a mixture will depend which point 66.4 grams of peracetic acid from the ad 40 on the amount of metal contamination it will encounter dition funnel were added over a ten-minute period. After under the normal circumstances, from about 0.5 to 500 a two-hour reaction period at 55-60° C. the mixture ppm. DPA (based on 100% endrin) should be adequate although smaller or larger concentrations may be used. TABLE I I claim: E?‘ect of metallic contamination on prepafatzon 0f 45 1. In the process for. preparing endrin from isodrin endrm by epoxidiz’ing isodrin with an organic per-acid, the im provement which comprisesconducting said epoxidation reaction in a reaction mixture containing dipicolinic acid. . Product— _ . Ni, ,, Fe , DPA Mol DPA Percent 2. In the process for preparing endrin from isodrin by Run N o. (p.p.rn ) (p.p.m.) (p.p.m.) per M01 Endrin 50 Metal (By epoxidation of said isodrin, and wherein the reaction Weight) mixture is contaminated with metal of the group con sisting of iron and nickel, the improvement whichcom 166 0. 581 7a. 6 prises performing said epoxidation in a reaction mixture 166 0. 613 78. 0 166 0. 651 70. 4 containing dipicolinic acid. 166 0. 677 64. 7 55 3. The process of claim 2 wherein the dipicolinic acid 166 0. 741 7 9. 4 239 0. 779 71. 5 is present in a ratio of from about 0.5 mole per mole of - 166 0; 819 78.3 metal contaminant to about 15 moles per mole of metal 166 1. 27 89.3 166 1. 45 91. 5 contaminant. 166 1. 61 91. 8 166 1. 75 39. 4 60 166 1-. 92 94. 3 References Cited in the ?le of this patent 166 2. 48 94. 7 ' 166 3.90 93. 8 UNITED STATES PATENTS 842 4. 06 96.0 429 4. 83 95. 6 2,676,132 Bluestone ______.._ Apr. 20, 1954 166 4. 93 97. 7 2,768,178 Bellin ______Oct. 23, 1956 531 5. 68 95. 5 166 6. 26 96. 7 65 2,768,179 Bellin ______Oct. 23, 1956 166 13.1 98; 5 2,768,180 Bellin ______Oct. 23, 1956 ' 166 97. 9 2,768,181 Bellin ______._ Oct. 23, 1956 2,776,301 Payne ______Jan. 1, 1957