United States Patent Office 2,969,402 Patented Jan. 24, 1961 2 preferred. In a more preferred aspect the upper tem 2,969,402 perature is about 10 C. The ratio of the three components, i.e., alkaline earth PREPARATION OF CATALYSTS FOR THE POLY metal hexammoniate, olefin oxide, and organic nitrile, MERIZATION OF EPOXDES can be varied over a wide range in the preparation of the Fred N. Hill, South Charleston, and John T. Fitzpatrick novel catalysts. The reaction is conducted, as indicated and Frederick E. Bailey, Jr., Charleston, W. Va., as previously, in an excess liquid ammonia medium. Thus, signors to Union Carbide Corporation, a corporation active catalysts can be prepared by employing from about of New York 0.3 to 1.0 mol of olefin oxide per mol of metal hexam No Drawing. Filed Dec. 29, 1958, Ser. No. 783,100 0. moniate, and from about 0.2 to 0.8 mol of organic nitrile per mol of metal hexammoniate. Extremely active 12 Claims. (CI. 260-632) catalyst can be prepared by employing from about 0.4 to 1.0 mol of olefin oxide per mol of metal hexammoniate, This invention relates to the preparation of composi and from about 0.3 to 0.6 mol of organic nitrile per mol tions which are catalytically active for the polymerization 5 of metal hexammoniate. It should be noted that the of epoxide compounds which contain a cyclic group com alkaline earth metal hexammoniate, M(NH3)6 wherein posed of two carbon atoms and one oygen atom. M can be calcium, barium, or strontium, contains alkaline Various divalent metal amides, H2N-M-NH2, and earth metal in the zero valence state. Thus, the concen divalent metal amide-alcoholates, H2N-M-OR, and 20 tration or mol ratio of the olefin oxide and the organic mixtures thereof, have been described in our copending nitrile is more conveniently based upon alkaline earth applications as being effective catalysts for the polymeriza metal per se rather than alkaline earth metal hexammon tion of epoxide compounds, notably olefin oxides. In the iate. above-depicted formulas the variable M is a divalent metal The olefin oxides contemplated as reagent in the prep such as magnesium, calcium, zinc, strontium, cadmium, 25 aration of the novel catalyst are those containing solely or barium, and the variable R is a monovalent organic carbon, hydrogen, and oxirane oxygen which is bonded radical such as alkyl, cycloalkyl, and the like. The instant to vicinal or adjacent carbon atoms to form an epoxy invention, in one aspect, also is directed to a novel class of group, i.e., catalysts which are extremely effective in polymerizing N / olefin oxides to useful polymers. These novel catalysts 30 can be advantageously employed in the suspension poly o O 2cN merization of, for example, ethylene oxide to produce granular poly(ethylene oxide). It is pointed out at this illustrative olefin oxides include, among others, ethylene time that the term "suspension polymerization process,' oxide, propylene oxide, 1,2-epoxybutane, 2,3-epoxybutane, as used herein including the appended claims, refers to 35 the epoxypentanes, the epoxyhexanes, the epoxyoctanes, polymerization in the presence of an inert, normally the epoxydecanes, the epoxydodecanes, 2,4,4-trimethyl liquid organic diluent in which the monomer employed is 1,2-epoxypentane, 2,4,4-trimethyl-2,3-epoxypentane, sty soluble and the polymer produced is insoluble. In con rene oxide, cyclohexylepoxythane, 1-phenyl-1,2-epoxypro trast to the granular ethylene oxide polymers produced pane, 7-oxabicyclo[4.1.0) heptane, 6-oxabicyclo[3.1.0 via the suspension polymerization route using the metal 40 hexane, 3-methyl-6-oxabicyclo[3.1.0) hexane, 4-ethyl-6- amides, the metal amide-alcoholates, or mixtures thereof, oxabicyclo3.1.0) hexane, and the like. Lower olefin ox as catalysts, it has been observed that, in general, granular ides are preferred, that is, ethylene oxide, propylene oxide, ethylene oxide polymers possessing relatively low reduced 1,2-epoxybutane, 2,3-epoxybutane, and the like. viscosity values are obtained (at faster rates of poly The organic nitriles which are employed in the catalyst merization) when employing the novel catalysts of this 45 preparation are, preferably, the saturated aliphatic hydro invention. This result was, indeed, highly unexpected and carbon nitriles. Among the organic nitriles which are unobvious. While the relatively high molecular weight contemplated include, for example, acetonitrile, pro polymers, e.g., poly(ethylene oxide), have commercial pionitrile, butyronitrile, valeronitrile, isovaleronitrile, utility for a wide variety of applications and uses, such capronitrile, caprylonitrile, caprinitrile, and the like. polymers must be molecularly degraded for various other 50 Lower saturated alphatic nitriles are preferred, that is, uses and applications. For instance, where the uses in acetonitrile, propionitrile, butyronitrile, and the like. tended for the polymer require a high concentration of Acetonitrile is most preferred. solids in solution without producing a solution that is The particular olefin oxide and the particular organic extremely viscous so as to be difficult to handle or process, nitrile employed in the catalyst preparation can affect the a relatively low molecular weight polymer is desired. It 55 polymer produced in the polymerization reaction. For also should be borne in mind that the molecular degrada instance, catalysts prepared with ethylene oxide are, in tion of relatively high molecular weight polymers by general, suitably for the production of higher molecular mechanical or physical means is an added inconvenience weight polymer products than those prepared with pro and uneconomical. pylene oxide and other olefin oxides. The novel catalysts of this invention are prepared by 60 It has been previously disclosed in our copending ap the mutual reaction and/or interaction of an alkaline plication that one mol of alkaline earth metal hexammon earth metal hexammoniate, an olefin oxide, and an or iate, e.g., calcium hexammoniate, will react with one mol ganic nitrile. The reaction is carried out in a liquid am of olefin oxide, e.g., ethylene oxide, in a liquid ammonia monia medium. In principle, the reaction temperature medium to give metal amide-alcoholates of the general can range from above about the freezing point of am 65 formula H2N-M-OR (for this illustration M is calcium monia, i.e., about -78 C., to the critical temperature and R is ethyl). These metal amide-alcoholates are active of ammonia, i.e., about --133° C. The preservation of a catalysts for polymerizing olefin oxides to relatively high liquid ammonia phase obviously requires pressurized molecular weight products. The most active catalysts, it equipment at reaction temperatures above the atmospheric was observed, were prepared by reacting one mol of alka boiling point of ammonia, i.e., about -33 C. A reaction line earth metal hexammoniate with about 0.5 mol of temperature in the range of from above about the freezing 70 olefin oxide to give a catalyst mixture containing alkaline point of the liquid ammonia medium to about 25 C. is earthalcoholate, metal amide and alkaline earth metal amide 2,969,402 3 - 4. In addition, one mol of alkaline earth metal hexam ing solid catalytically active material in the reaction ves moniate in a liquid ammonia medium will react, in the sel. After this, the catalytically active material can be absence of an olefin oxide, with about 0.5 mol of an suspended or slurried in an inert, normally-liquid organic organic nitrile, particularly a saturated aliphatic nitrile. vehicle such as, for example, lower dialkyl ether of alky Though this reaction is not fully understood, it appears lene glycol, e.g., the dimethyl, diethyl, or dipropyl ethers that the organic nitrile is reduced, first to an imine-type of diethylene glycol; dioxane; saturated and cycloaliphatic structure, and subsequently to an amine-type structure. hydrocarbons, e.g., hexane, heptane, cyclohexane, or 2 It can be conjectured that a substantial portion of the methyl-cycloheptane; and the like. imine or amine is displaced from the alkaline earth metal The novel catalysts of this invention are useful in effect by reaction with the excess liquid ammonia to give alkaline 10 ing the polymerization of epoxide monomers which con earth metal amides. Whatever the theory or reaction tain a cyclic group composed of two carbon atoms and mechanism may be, these reaction products are catalysts one oxygen atom. These epoxide monomers can be for the polymerization of olefin oxides; however, they characterized by the following formula: are considerably less catalytically active than the reaction products containing alkaline earth metal amide-al 15 R R. coholates described previously. On the other hand, the es ze novel catalysts of this invention are extraordinarily active E. O H catalysts for effecting the polymerization of, for example, wherein each R1, individually, can be hydrogen, haloaryl, olefin oxides. In general, the rates of polymerization are or a hydrocarbon radical free from ethylenic and ace higher, and the molecular weights of the polymers 20 tylenic unsaturation such as, for example, alkyl, aryl, produced are lower, by the use of the novel catalysts of cycloalkyl, aralkyl, or alkaryl radicals. In addition, both this invention as compared to the use of catalysts pre R1 variables together with the epoxy carbon atoms, i.e., pared by the reaction of an olefin oxide or an organic the carbon atoms of the epoxy group, nitrile with alkaline earth metal hexammoniate. The superiority