United States Patent Office Patented Sept
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3,400,113 United States Patent Office Patented Sept. 3, 1968 1. 2 3,400,113 -C=N wherein the free valence is satisfied by a sub MOLECULAR WEIGHT CONTROL stantially inert, if not completely inert, organic moiety. OF POLYDOLEFNS By "inert” is meant that the organic moiety reacts neither Hermann Winter and Heinrich Weber, Marl, Germany, with the other components of the catalyst composition assignors to Chemische Werke Huls Aktiengesellschaft, nor with the monomer itself. It is to be understood, how Marl, Germany ever, that the nature of the organic moiety may be im No Drawing. Filed Dec. 23, 1963, Ser. No. 332,892 portant with respect to the extent of molecular weight Claims priority, application Germany, Jan. 16, 1963, regulation, bearing in mind that if the organic compound C 28,914, C 28,915 8 Claims. (C. 260-94.3) contains at least one -C=N group, there will be at least O a finite regulation of the molecular weight. Suitable nitriles, therefore, include the saturated and unsaturated aliphatic, cycloaliphatic and aromatic nitriles ABSTRACT OF THE DISCLOSURE with one or more nitrile groups. Preferably, the aliphatic For obtaining polydiolefins of controlled reduced mo nitriles contain 2-16 carbon atoms, 1-4 nitrile groups, lecular weights, the process of polymerizing a conjugated 5 and 0 to 2 unsaturated bonds; still more preferably, the diolefin of 4-6 carbon atoms with a Ziegler catalyst, aliphatic moiety is hydrocarbon. The cycloaliphatic ni particularly one based on cobalt, and added thereto a triles preferably contain 4 to 13 carbon atoms, 1-4 ni nitrile, particularly an azo-bis-carboxylic acid nitrile, the trile groups and 0 to 2 unsaturated bonds. Likewise, the more nitrile added to the catalyst composition, the lower aromatic nitriles preferably contain 7 to 15 carbon atoms, the molecular weight of the polymer. 20 and 1-4 nitrile groups. Specific examples of the nitriles of this invention in ammu Tamim clude acetonitrile, propionitrile, butyronitrile, lauric acid This invention relates to polymers of diolefins, in par nitrile, cyanogen, malonitrile, adipic acid nitrile, dihy ticular to the regulation of the molecular weight of the dromuconic acid nitrile, hexahydrobenzoic acid nitrile, polymer when produced in the presence of a Ziegler 25 benzonitrile, stearylnitrile, tetracyanoethane, cyclodo type catalyst. decylnitrile, terephthalonitrile, phthalonitrile, 3-naphthoic It is known that during the polymerization of diolefins acid nitrile. Suitable af3 unsaturated nitriles include with Ziegler-type catalysts (reaction products of com acrylonitrile, crotylonitrile, fumaric acid nitrile and mu pounds of the transition metals on the one hand, and conic acid nitrile. metals, metal hydrides, or metal-organic compounds of 30 Highly preferred nitriles of this invention are azo-bis the metals of Groups I to III of Mendeleef's Periodic carboxylic acid nitriles of the formula: Table, on the other hand), the molecular weight of the polydiolefins thus produced can be regulated by perform ing the polymerization in the presence of hydrogen. It wherein R1 and R2 are aliphatic or cycloaliphatic resi is also known that the molecular weights can be regulated 35 dues with 1 to 6 carbon atoms, which may be in the form by the addition of ox-olefins and non-conjugated diolefins. of a 6-atom ring. Examples of these nitriles include 2 Finally, it is also possible to influence the molecular azo-bis-isobutyric acid-nitrile, 2-azo-bis-2-methyl-butyric Weights within certain limits by changing the composition acid-nitrile and 1-azo-bis-1-cyclohexane - carboxylic-acid of the inert solvents, especially of aliphatic and aromatic nitrile. hydrocarbons. 40 The nitriles of this invention are prepared, in general, Actually the polydiolefin molecular weights are lowered by conventional methods, reference being made to any by additions of hydrogen, ox-olefins and non-conjugated standard textbook of organic chemistry. With respect to diolefins and increased amounts of aliphatic compounds the preparation of the azo-bis-carboxylic-acid-nitriles, we in the solvent mixtures. All of the preceding methods, refer to Dox Am. Chem. Soc., 47, p. 1471 (1925); Over however, involve difficulties. Some of them require the 45 berger, Organic Synthesis, 32, p. 16 (1952). use of higher pressures or larger amounts of the regulat The nitriles are used in 0.01 to 100 molar, and prefer ing compounds. Certain of the regulators are difficult to ably in 0.1 to 10 molar amounts, relative to the amounts obtain, and are effective only within a very narrow con of the transition metal compounds. Generally, about equi centration range which is difficult to maintain. 50 molar amounts are used, the amount being determined by The main object of this invention, therefore, is to the desired reduction of molecular weight. The larger the provide an improved process for the regulation of the amount of nitrile, the greater will be the reduction of the molecular weight of polymers of diolefins. molecular weight. Nitriles are especially suitable for regul Another object is to provide novel catalyst composi lating the molecular weight of polybutadienes with high tions. 14 contents, produced with mixed catalysts of cobalt Upon further study of the specification and claims 55 compounds and aluminum organic compounds. other objects and advantages of the present invention The diolefins that can be advantageously polymerized will become apparent. according to this invention are those having 4-6 carbon It has been discovered that the molecular weights of atoms, and of course the two double bonds must be con polydiolefins obtained by the polymerization of diolefins jugated. Hydrocarbon diolefins are preferred such as iso with Ziegler-type catalysts preferably those catalysts com 60 prene, pentadiene-(1,3) and butadiene-(1,3) and mix posed on the one hand of compounds of the transition tures thereof. Furthermore, copolymers of one or more metals and on the other hand of metals, metal hydrides diolefins with one or more monolefins of 2 to 8 carbon or metal organic compounds of the metals of Groups I atoms are included, as long as the mol ratio of diolefin to III of Mendeleef's Periodic Table, and optionally in to monolefin monomer is not less than 0.5:1, respectively. the presence of inert solvents, can be advantageously 65 Preferred monolefins are hydrocarbons such as butene regulated if the polymerization is performed in the pres (1) and butene-(2). ence of a small amount of a nitrile. Suitable transition metal compounds include those of In other words, the essence of this invention is the ad titanium as, for example, titanium tri- and tetrachloride dition of a nitrile to a Ziegler-type catalyst for the po and those of vanadium as, for example, vanadium tri lymerization of diolefins. This nitrile is an organic com 70 chloride, tetrachloride and oxytrichloride and vanadium pound containing at least one radical of the formula (III)-acetylacetonate. Especially suitable are the cobalt 3,400,113 3 4 . compounds such as cobalt chloride, cobalt bromide, co tinual removal of catalyst containing polydiolefin solu balt acetate, -propionate, -butyrate, -octoate, -Stearate or tion in a known manner. The polymerized mixture is complex compounds of cobalt such as cobalt acetylace worked up in a known manner, as for example, by addi tonate. tion of ethanol, methanol or isopropanol, followed by As metals of Groups I to III of the Periodic Table, filtration. Of special interest is the known method of especially suitable are sodium, lithium and aluminum, working it up with water. while suitable metal hydrides include sodium hydride, cal Without further elaboration, it is believed that one cium hydride, aluminum hydride and lithium-aluminum skilled in the art can, using the preceding description, hydride. As metal organic compounds, those with metal utilize the present invention to its fullest extent. The fol carbon bonds are suitable, such as metal organic com lowing preferred specific embodiments are, therefore, to pounds of the alkali metals as, for example, butyl-mag 10 be construed as merely illustrative, and not limitative of nesium bromide and phenyl-magnesium bromide, and es the remainder of the specification and claims in any way pecially aluminum compounds as, for example, aluminum whatsoever. trialkyls, aluminum triaryls and aluminum triarylalkyls Example 1 such as trimethylaluminum, triethyl aluminum, triisobutyl 15 aluminum, triphenyl aluminum, tri-(ethylphenyl)-alumi Into a vessel equipped with an agitator and sealed off num, and mixtures thereof; furthermore, also dialkyl against air and moisture there is added 1 liter anhydrous aluminum-monohalides, diaryl-aluminum - monohalides benzene, 108 g. (2 mols) butadiene-(1,3) containing and diaralkyl-aluminum-monohalides such as diethyl 0.01% isobutane, 0.01% n-butane, 0.1% butene-(1) and aluminum-monochloride, diphenyl-aluminum - monochlo 20 isobutene and 0.05% trans-butene-(2); 0.4 g. (9.74 milli ride, diethylphenyl-aluminum-monochloride, diethyl-alum mole) acetonitrile; 0.164 g. (0.46 millimole) cobalt inum-monobromide, finally also the monoalkyl aluminum acetylacetonate; and 2.48 (20 millimole) ethyl aluminum dihalides, monoaryl aluminum dihalides, monoaralkyl sesquichloride. An active polymerization commences, and aluminum dihalides such as monoethyl aluminum dichlo the temperature is then kept between 20 and 25 C. by ride and monoethyl aluminum dibromide. Also suitable 25 external cooling. After 1.5 hours the polymerization is are the dialkyl aluminum hydrides as, for example, di terminated by adding acetone. The polybutadiene precipi ethyl aluminum monohydride, diisobutyl aluminum mono tated by the dropwise addition of alcohol, is washed, and hydride, etc. Also suitable are hydride of aluminum then dried at 30° C. in a vacuum chamber. 100 g. polymer halides or their etherates, as, for example, hydride of (93%) are obtained with an RV=1.6 (reduced vis aluminum dichloride. 30 cosity=viscosity number, (see Makromolekulare Chemie The molar ratio of the transition metal compound to 38, p.