3,250,760 United States Patent cc, Patented July 12, 1966

1 2 3,260,760 chlorinated hydrocarbons to decomposition is shown by STABILIZED CHLORINATED HYDROCARBQN the accelerated laboratory test carried out as follows; ‘ COMPOSITIONS 150 cubic centimetres of , for example, Charles Domen and André Ryckaert, Brussels, Belgium, and a test piece of aluminum are placed in a 300 cubic and Charles .legge, Zurzacll, Aargau, Switzerland, as centimetres ?ask and a Soxhlet extraction apparatus pro siguors to Solvay & Cie, Brussels, Belgium, a Belgian vided with an extractor of 65 cubic centimeters. The - company ' No Drawing. Filed Oct. 8, 1963, Ser. No. 314,650 ?ask is electrically heated and the trichloroethylene is Claims priority, application Belgium, Oct. 31, 1962, rapidly brought to boiling under re?ux at a constant rate 2°O 330 while the apparatus is traversed by a current of oxygen 6 Claims. (or. 260-6525) and illuminated by a ?uorescent lamp of the “blue actnic” type. During the time of the test, the rate of release of The present invention comprises a process for the sta the acid vapours leaving the apparatus is measured. This bilization of chorinated hydrocarbons, particularly tri rate, very small at ?rst, becomes suddenly very large chloroethylene and perchloroethylene, with a view to while the trichloroethylene darkens in color and trans avoiding the decomposition of these products and the si forms into a black tarry mass. The resistance of the tri multaneous formation of oxidation products during stor chloroethylene under test is measured by the time, ex age or during their use. pressedin hours counted from the start of the experiment It is known that, under the in?uence of heat and oxy when the sample reaches boiling point until the time when gen, chlorinated hydrocarbons undergo an oxidation which the release of the acid abruptly becomes very rapid and is catalyzed by di?erent agents such as light and certain exceeds 15 .10—3 gram moles per hour. metallic salts, in particular the salts of iron, aluminum The following table shows resistance to decomposition and magnesium. of unstabilized trichloroethylene and trichloroethylene To retard this oxidation it has been proposed to add to stabilized with various phenolic and/or epoxide com the chlorinated hydrocarbons small amounts of various pounds.

No ______._ Phenol, 200 mgrJl. __ o-Cresol, 200 mgrJl. _ m-Cresol, 200 mgr./l_ p-Oresol, 200 mgr./1_.

products such as , inorganic or organic basic prod The results of these experiments show in the last seven ucts, , epoxide compounds etc. columns, the synergistic effect realized by the use of a Recourse has likewise been taken to the addition of mixture formed on the one hand by an epoxide compound two or more stabilizers which exert a synergistic action. having another function containing oxygen and on the Thus, in a previous patent of the applicants (Belgian other hand of a phenolic compound which can be phenol, patent speci?cation No. 562,288) it has been shown that one of its higher homologues or a diphenol. Columns 2, the simultaneous addition of phenol and of the epoxide 3 and 4 of the table enable one to see that, with the excep compound gives results superior to the sum of the sta tion of hydroxy-, n0 synergistic effect exists be bilization action of the two components; nevertheless, this tween phenols and epoxide compounds which carry no action has only been con?rmed when hydroxy-benzene is other function containing oxygen. The application of the used as a phenolic compound and not in the case where process according to the invention thus leads to new higher phenols are used such as cresols or thymol. results. The applicants have now found that a synergistic action The quantities of stabilizing materials to be applied are can be obtained which extends equally to other phenolic in general comprised between 0.05 and 0.5 gram per litre compounds, by selecting a co-reactive epoxide compound for the monophenolic compound and from 0.5 to 10 grams from those carrying in the molecule at least one further per litre for the epoxide compound having one or more function containing oxygen. This other function contain other functions containing oxygen. The proportions ing oxygen may be an alcoholic function, or an ester or which appear to be most advantageous are from 0.1 to 0.2 for example, it may consist of a second epoxide gram for the monophenols and 1.5 to 5 grams for the group. In the synergistic mixture according to the in epoxides, per litre of chlorinated hydrocarbon to be sta vention, those in which the phenol is selected from ortho bilised. diphenol (or catechol) and its substitution derivatives, When a diphenol is used as phenolic compound, the such as p-tert-butylcatechol and p-methylcatechol give amount of it to be applied can be brought down between good results even with small amounts of the phenolic 0.01 and 0.5 gram per litre. It can be seen from the table compound. that amounts of catechol as low as 25 milligrams per The stabilization action of the various compounds and litre already permit good stability to be obtained, due to systems of compounds used to improve the resistance of the mutual synergistic action of the two constituents and 4 not to the action of the diphenol alone (for example, 1,2-epoxy-3-ethoxypropane, allyl-glycidyl ether, 1,2,3,4-di catechol 25 milligrams per litre and 1,2-epoxybutane 1500 epoxybutane. milligrams per litre). 4. A stabilized chlorinated hydrocarbon containing per If desired, other known compounds can be added to the litre of said chlorinated hydrocarbon, a mixture of about combination stabilizing substances which forms the ob 0.05 gram to 0.5 gram of lower-alkyl phenol and about ject of the invention, in particular inorganic or organic 0.5 gram to 10 grams of an epoxide which is selected substances having an alkaline reaction which modify the from the group consisting of glycidol, 1,2-epoxy-3-cyclo initial pH of the chlorinated hydrocarbon. pentanol, glycidyl acetate, 1,2-epoxy-3-methoxypropane, The stabilizing compositions according to the invention 1,2-epoxy-3-ethoxypr0pane, allyl-glycidyl ether, 1,2,3,4 are particularly e?iective in the case of the stabilization diepoxybutane. ' of trichloroethylene. They can however, without depart 10 5. A stabilized chlorinated hydrocarbon, containing per ing from the scope of the invention, be used for the sta litre of said chlorinated hydrocarbon a mixture of about bilization of perchloroethylene and other chlorinated hy 0.01 gram to 0.5 gram of catechol and about 0.5 gram to 10 grams of an epoxide selected from the group consisting drocarbons such as chloromethanes, dichloroethanes, tri of glycidol, 1,2-epoxy-3-cyclopentanol, glycidyl acetate, , dichloroethylenes, allyl chloride, chloro 15 propanes, chloropropenes, etc., and their mixtures. 1,2-epoxy-3~methoxypropane, 1,2-epoxy-3-ethoxypropane, The applicants are aware that the use of pyrocatechol allyl-glycidyl ether, 1,2,3,4-diepoxybutane. and other diphenols, taken separately, for the stabilization 6. A stabilized chlorinated hydrocarbon containing per of low molecular weight chlorinated hydrocarbons, has litre of said chlorinated hydrocarbon a mixture of about 0.01 gram to 0.5 gram of lower-alkyl catechol and about already been described (German patent speci?cation No. 20 573,105, U.S. patent speci?cation No. 2,008,680). 0.5 gram to 10 grams of an epoxide which is selected from We claim: the group consisting of glycidol, 1,2-epoxy-3-cyclopen 1. A stabilized chlorinated hydrocarbon containing a tanol, glycidyl acetate, 1,2-epoxy-3~methoxypropane, 1,2 stabilizing amount of a mixture of a phenolic compound epoxy-3-ethoxypropane, allyl-glycidyl ether, 1,2,3,4-di selected from the group consisting of lower-alkyl phenol, epoxybutane. catechol, and lower-alkyl catechol and an epoxide selected References Cited by the Examiner from the group consisting of glycidol, 1,2-epoxy-3-cyclo pentanol, glycidyl acetate, 1,2-epoxy-3-methoxypropane, UNITED STATES PATENTS 1,2-epoxy-3-ethoxypropane, allyl-glycidyl ether, 1,2,3,4 2,564,194 8/1951 De Nie et a1 ____ .._260--652.5 X diepoxybutane. 30 2,585,506 2/1952 Shokal et a1 ______260—652.5 2. A stabilized chlorinated hydrocarbon according to 2,906,782 9/1959 Ferri et a1. ______260—652.5 claim 1 wherein said phenolic compound is p-tert-butyl 2,935,537 5/1960 Daras ______260—652.5 catechol. 2,947,792 8/1960 Skeeters ______.__ 260—652.5 3. Stabilized trichloroethylene containing a stabilizing 2,981,760 4/1961 Fer-ri et a1 ______260—652.5 35 amount of a mixture of a phenolic compound selected from the group consisting of lower-alkyl phenol, catechol, LEON ZITVER, Primary Examiner. and loWer-alkyl catechol and an epoxide which is selected DANIEL D. HORWITZ, Examiner. from the group consisting of glycidol, 1,2-epoxy-3-cyclo pentanol, glycidyl acetate, 1,2-epoxy-3-methoxypropane, 40 M. M. JACOB, Assistant Examiner.