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United States Patent Office Patented Oct 3,278,400 United States Patent Office Patented Oct. 11, 1966 1. 2 3,278,400 R can be a different hydrocarbon group, especially an ELECTROFORMANG OF BERYLLUM alkyl or aryl group, or in a mixture of both of them. Walter Strohmeier, Wurzburg, Germany, assignor to Ethyl A distinct benefit of the pure complex salts employed Corporation, New York, N.Y., a corporation of Virginia herein is that they generally have a melting point range No Drawing. Filed Nov. 6, 1962, Ser. No. 235,880 of from about room temperature to about 100° C. where Clair as priority, application Germany, Nov. 14, 1961, by the electrolytic deposition of beryllium can be carried St 18,556 out at room temperature or slightly above, and at any rate 9 Claims. (C. 204-3) at relatively low temperatures. Thus, it is now possible This invention relates to a novel electrolytic process for for the first time to beryllium coat materials which are IO non-heat resistant, for example artificial materials or plas the production of beryllium metal. Specifically, this in tics having first been coated with a conductant layer, e.g. vention relates to the electrolytic separation of beryllium silver. metal from complex compounds of organometallic beryl The following examples demonstrate the unique results lium compounds of the general formula achieved in the practice of the present invention wherein MX nBeR 5 all parts are by weight unless otherwise specified. in which R is an alkyl, cycloalkyl, alkaryl, aryl, or aralkyl Example I group, MX is a suitable metal salt or a salt-like com pound which is capable of reacting with BeR to form a An electrolyzing vessel comprising a glass cell having a complex, and in can be an integer from 1 to 6, preferably side extension and interchangeable electrodes was set up. from 1 to 2. 20 Both the anode and the cathode was constructed of plat The eelctrolytic deposition of beryllium metal from suit inum metal. The glass cell was purged with nitrogen able Salt melts has been known for some time and its which was employed throughout electrolysis as a protect feasibility technically demonstrated. However, due to the ing gas or inert atmosphere to prevent contamination of necessary use of high temperatures when working with the electrolyte and effected coating. salt melts, that type of process is not suitable to the coat 25 The electrolyte employed in this instance was the potas ing of cathodes which are structurally incapable of with sium fluoride complex of bis(diethylberyllium) standing high temperatures, viz. non-heat resistant ma terials. dissolved in diethylberyllium Be(CH) in a weight A low temperature approach taken in the art to electro ratio of 1:2. The glass cell was charged with the electro lytically deposit beryllium has been by the use of non 30 lyte through the side extension whereafter a direct current aqueous solutions or electrolytes which do not possess was applied to the cell. During electrolysis, 1.7 volts at proton activity or in other words, those having a minimum a current density of 0.62 amp/dim.2 was maintained on acidity to avoid reaction with the beryllium in the system. the cell. The temperature of the cell bath during the plat These electrolytes comprise solutions of beryllium salts ing operation was 85 C. The electrolyte was vigorously or of organometallic compounds and organic solvents, for 35 stirred throughout the operation. example ethers, nitrogen bases, or hydrocarbons. How The experiment was terminated and inspection of the ever, the above prior art approach has left much to be de cathode revealed a shining beryllium coating. sired and has not proven successful for the preparation of When dicyclopentadienylberyllium is substituted for the adheernt polishable beryllium coatings. Hence, a need diethylberyllium in the procedure of Example I, similar exists in the art for a process whereby a very adherent 40 results are obtained. polishable beryllium coating can be effected at low tem Example II peratures. To approach it from another direction, a need The apparatus of Example I was employed, except in exists in the art for a low temperature beryllium deposi this instance the cathode was constructed of copper. A tion process whereby non-heat resistant materials can be very adherent gray beryllium coating which was capable given a very adherent polishable beryllium coating. of being polished was realized. An object of this invention is to provide a new electro lytic process for the production of beryllium metals. An Example III other object of this invention is to provide beryllium coat The apparatus of Example I was employed, except that ings by a low temperature process which coatings have in this instance the cathode was constructed of copper. physical properties heretofore unobtainable in the art. The electrolyte consisted of one part of the cesium fluo Yet another object of the invention is to provide a new ride complex of bis(diethylberyllium) CSF2Be (C2H5)2 electrolytic beryllium plating process whereby unique dissolved in two parts of diethylberyllium Be (C2H5). beryllium coatings can be prepared on substrates hereto A voltage of 1.5 volts at a current density of 0.80 amp/ fore not amenable to present day beryllium plating proc dm. was applied on the cell which was maintained at a esses. These and other objects will come to light as the 55 temperature of 80 C. A silvery, smooth beryllium coat discussion proceeds. ing was obtained. These objects are accomplished by providing a process Substitution of dihexylberyllium for the diethylberyllium for the electrolytic separation or deposition of metallic of Example III gives similar results. beryllium of complex salts of organometallic beryllium compounds of the general formula 60 Example IV The apparatus of Example I was employed, except that MX nBeR in this instance a silver cathode was utilized. The elec wherein BeR2 represents a dialkyl, dicycloalkyl, dialkaryl, trolyte employed was the tetraethylammonium chloride diaryl, or diaralkyl beryllium moiety complexed with ap complex of diethylberyllium N(CH3)4C12Be (C2H5)2 propriate salts of the type MX, wherein M can be a metal 65 at an electrolyzing temperature of 65 C., a voltage of 1.7 ion or an organic cation as, for example, tetraethylam volts, and a current density of 0.6 amp/dm.2. Beryllium monium or tetraisobutylammonium, X is a suitable anion, Separated out on the silver cathode as a shiny coating e.g. fluoride, chloride, cyanide, or alkoxide, and n is an in which was highly polishable. teger from 1 to 6, and preferably from 1 to 2. The elec When diphenylberyllium, dibenzylberyllium and dixylyl trolyte can comprise either the complex salt in a pure 70 beryllium are individually substituted for the diethylberyl liquid state or a solution of the complex salt in a suitable lium in the procedure of Example IV, similar results are solvent, preferably in excess BeR or in BeR'2 wherein obtained. 3,278,400 3 4. lium, magnesium, calcium, strontium, and barium. Gen Example V erally speaking, the salts of the alkaline earth metals The apparatus of Example I was employed, except in of atomic numbers 20-56-i.e. calcium, strontium, and this instance a sheet of silver was used as the cathode and barium-are preferred for use in this invention. The a plate-like piece of beryllium as the anode. The elec alkaline earth metal salts can be salts of organic or in trolyte was the potassium fluoride complex of diethylbe organic acids, the latter being generally more efficacious. ryllium KF2Be (C2H5)2]. A voltage of 1.8 volts and Thus, the alkaline earth metal salts include the alkaline a current density of 0.5 amp/dm. was applied upon the earth metal halides, alkaline earth metal alcoholates cell. Beryllium was dissolved at the anode while a be (MOR), wherein the hydrocarbon portions contain up to ryllium coating was deposited on the silver cathode. 10 and including about 18 carbon atoms; alkaline earth pseu Use of the potassium cyanide complex of diethylberyl dohalides as, for example, the alkaline earth metal cy lium KCN2Be (C2H5) in the procedure of Example anides, cyanates, thiocyanates, amides, mercaptides, and V gives similar results. the like; organic acid salts as, for example, the alkaline As mentioned previously and as demonstrated by the earth metal salts of organic acids wherein the hydrocarbon above examples, the electrolyte can comprise a pure com 15 portions have up to and including about 18 carbon atoms. plex salt of an alkyl, cycloalkyl, alkaryl, or aralkyl beryl Typical examples of such alkaline earth metal salts in lium compound or the electrolyte can comprise the com clude calcium chloride, bromide, iodide, or fluoride; cal plex dissolved in a suitable solvent where the melting point cium formate, acetate, propionate, phenolate, ethylate, of the complex is greater than 100° C. Thus, in the benzoate, isobutyrate, and the like; including such com latter technique by the proper selection of the quantity 20 pounds wherein beryllium, magnesium, strontium, or bari relationships of the salt complex of the organoberyllium um are substituted for calcium. Thus, in general, any compound and the solvent, it is possible to obtain an elec alkaline earth metal salt capable of complexing with the trolyte which is fluid at room temperature and below. organoberyllium compounds employed pursuant to this Exemplary of the organoberyllium compounds capable invention can be used. However, the alkaline earth metal of complexing with the salts employed herein are: di 25 halides, especially the fluorides and cyanides comprise par methylberyllium, diethylberyllium, dipropylberyllium, di ticularly preferred alkaline earth metal salts. tertiarybutylberyllium, dihexylberyllium, dioctylberyllium, Of the tetraalkylammonium salts used in this invention, didecylberyllium, dicyclopentadienylberyllium, dicyclo the tetraalkylammonium halides, especially the fluorides hexylberyllium, diphenylberyllium, dibenzylberyllium, di and most especially the chlorides, are preferred.
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