CONTRIBUTIOSS TO T H E CHEMISTRY O F BERYLLICM Beryllium I. Electrolysis in Son-Aqueous Solvents*
____
BY HAROLD bI?,IMOSS BOOTH A S D GILBERTA G. T O R R E P
Introduction Although thc probable usefulness of metallic beryllium has long been recognized, only in very recent years have any successful methods of supplying beryllium in quantity been developed. However, these methods require very carefully purified material and the maintenance of high fusion temperatures. The present research was undertaken to investigate as wide a field as possible of non-aqueous low temperature reduction methods. The only successful non-electrolytic reduction method uses metallic sodium or potassium.' The fine particles of reduced beryllium must be separated from the residues of alkali metal, beryllium salt, and alkali salt formed during reduct,ion. As beryllium is soluble in .alkali hydroxide the mix must be extracted with alcohol. The resultant metal is very finely divided, difficult to melt, and usually badly oxidized. W. R. Veazey (U. S.Pat. 1,515,082, S o v . 1 1 , 1924) found that beryllium fluoride when plunged int'o molten magnesium was reduced and gave a mixture of beryllium and magnesium. When magnesium was plunged into fused beryllium fluoride t'he reaction was so violent that the materials were blown out of the crucible. Lebeau and others2 have electrolyzed fused salts or solutions of beryllium salts in fused solvents. These methods require high temperatures and make the process expensive and difficult to control. Metallic fogs are easily produced particularly when the temperature of the melt exceeds a certain suitable maximum, and thus much of the metal is lost and the efficiency of the process lowered. Lebeau3 prepared hexagonal crystals of the metal by electrolyzing the fused double fluorides of sodium, or potassium, and beryllium. During our qualitative test of this method, the surface of the melt was continually illuminated by the flashes of light from what was apparently the burning metal. Recently, however, work by another investigator4 in this field has shown that this method may be used successfully by carefully controlling the fusion tem* The study of beryllium was begun in this laboratory in 1921 and has been continued by various workers cooperating with the senior author. A preliminary announcement of these papers appeared a s a note to the editor in J. Am. Chem. So?., 52, 2j81 (1930). This work was presented a t the Symposium on Son-Aqueous Solutions a t the Cincinnati meeting of the American Chemical Society, Septemher, 1930. Wohler: Ann. Chim. Phys., (2) 39, 7 7 (1828); Hunter and Jones: Trans. Am. Electrochem. SOC., 44, 3 j (1923). "ebeau: Cornpt. rend., 126, 744 (1898); Goldschmidt and Stock: Brit. P a t . 192, 970, April 19, 1922; Chem. Abs., 17, 3459 (1923); E. A. Engle's Thesis, University of Illinois. Elektrochem. Z., 5 , 31 (1898); Am. Chem. J., 27, 487 (1898). Private communication to the Authors.
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HAROLD S I M M O S S BOOTH AND GILBERTA G . TORRET
perature and the current densities. Other fused mixtures have been used but many that were stated to produce metal' are now found to be absolutely nonconducting. Recently the Siemens-Halske method, invented by Stock and GoldSchmidt,* using sodium-beryllium fluoride in fused barium fluoride has been developed to a satisfactory commercial scale process, though it is said that barium-beryllium fluoride is now used. The metal is obtained in massive form but extremely high temperature operation is an undesirable factor. Many salts possess a considerable solubility in non-aqueous media and their solutions are known to conduct electricity. Several workers3 have investigated certain properties of these solutions but they have interested themselves mainly in the determination of conductivities a t various dilutions and therefore have not obtained cathode products. Since certain other metals had been prepared by electrolysis of non-aqueous solutions of their salts this method seemed to have possibilities in the preparation of metallic beryllium. Except for the process of Siemens-Halske attempts to prepare metallic beryllium have resulted in precipitation of small non-coherent crystals. In the non-aqueous solutions it was hoped that a coherent plating of metallic beryllium could be obtained.
Choice of Solvents Beryllium compounds have such a remarkable tendency to hydrolyze in the presence of the slightest traces of moisture that all solutions containing water or which furnish hydroxyl ion are useless. Fortunately many beryllium salts are soluble in non-aqueous solvents and the solutions are stable in the absence of moisture. Solvents from which other metals have been prepared by electrolysis of solutions of their salts were first tried. Plotnikoff4 prepared metallic aluminum by the electrolysis of a solution of aluminum bromide in ethyl bromide, H. E. Pattens repeated the work and stated that aluminum could be deposited with a current densit'y of . 2 3 amperes per square decimeter. Kahlenberge has prepared metallic lithium from a solution of the chloride in pyridine. Arguing from the usual analogy between first members of successive series of the periodic table and especially of the transitional elements, it seemed reasonable t o expect that beryllium could be prepared from pyridine solutions of its salts. This phase of the study will be discussed in the second part on the electrolysis of beryllium salts dissolved in organic nitrogen compounds. The organic salts of beryllium in particular are very soluble in such liquids as alcohol, chloroform, and ethyl bromide. Apparently the conductivities of these solutions have never been investigated. 'Warren: Chem. Sews, 72, 310 (189j);2. anorg. Chem., 13, 364 (189j);Borchers: Z. Elektrotech. u. Elektrochem., 1895, 39; J. Chem. Soc. 70, (21, jZI (1896). Illig: Trans. Am. Electrochem. Soc., 54, Z I I (1928). 3 C a d y : J. Phys. Chem., 1, 707 (1897);Groening with H.P. Cady: 30, 1597 (1926); Kraus and Brag: J. Am. Chem. Soc., 35, 131j (1913). J. Russ. Phys. Chem. Soc. (3), 466 (1902). J. Phys. Chem., 8, 548 (1904). J. Phys. Chem., 3, 602 (1899).
THE CHEMISTRY OF BERYLLICM
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Purification of Beryllium Material by Crystallization as Beryllium Basic Acetate Before preparing the individual compounds it was most convenient to purify the whole mass of beryllium material to avoid tedious and often impossible purification of the individual products. Beryllium is most easily separated from all metals except iron and aluminum by precipitation as the hydroxide with dilute ammonia; the iron and aluminum are then separated by recrystallization of the beryllium as beryllium basic acetate. Commercial beryllium nitrate, Be(NO3)%4 H 1 0 , was dissolved in a large quantity of water and precipitated with very dilute SHIOH(z - 3 7 ) . The gelatinous
FIG.I
precipitate of hydroxides mas separated from soluble impurities by inverse filt,ration with a porcelain Pukal suction funnel and washed free from ammonium salts with pure water. The cakes of partially dried hydroxide were dissolved in acetic acid and the solution evaporated in large porcelain dishes t o a syrupy consistency. Parsons and Robinson' recommend that this material be dissolved in boiling glacial acetic acid from which it should separate in gleaming crystals of pure beryllium basic acetate. To prevent too rapid crystallization of the salt it is necessary to filter the solution on a heated funnel. This causes considerable evaporation of acetic acid with consequent unbearable working conditions. d special apparatus was devised for this final stage of the purification. The apparatus, shown in Fig. I , consisted of two five-liter, round bottomed Pyrex flasks, A and B. , provided with two-holed rubber stoppers. The main flask, A, carried a condenser, F, and a five millimeter delivery tube leading to the second flask. The second flask, B, carried a two-way stopcock permitting entrance of air or connection to a suction pump. The tube leading from flask 1
J. Am. Chem. SOC.,28,jjj (1905).
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HAROLD SIMWONS BOOTH AXD GILBERTA G. TORREY
A to flask B was provided with a device for filtering the solution as it was transferred. This consisted of a short portion of wide tubing, G, fused to the narrow delivery tube, the wide end covered with a porcelain Witt plate, C, held in position by means of a fibre extraction thimble, T. The syrupy mass of beryllium material was placed in flask A with a quantity of glacial acetic acid and boiled t o incipient crystallization. The boiling saturated solution of basic acetate, was then transferred to flask B by applying gentle suction at one exit of the stopcock and was filtered from any residue of hydroxide or other insoluble impurity on passing through the thimble and porcelain plate. On cooling the solution deposited large quantities of very pure beryllium basic acetate. One or two similar recrystallizations from glacial acetic acid produced pure beryllium basic acetate. The material as prepared by the method just described is pure but cannot be used directly in the preparation of other beryllium salts. The basic carbonate, hydroxide, and oxide are the most convenient forms to use in the preparation of other beryllium compounds, especially salts of weak acids or compounds requiring fusion.
Preparation of Beryllium Hydroxide and Oxide After the pure beryllium basic acetate had been obtained the next, problem was to convert it to a usable form without introducing sonit' impurity. Hecause of its volatility and moderate stability the basic acetate cannot be converted economically to oxide by ignition, but may be heat,ed with nitric wid to form the nitrate. The basic acetate may be convrrtrti to basic carbonate by st'eam distillation of an ammonium carbonate solution of the basic acrtate. Both methods permit contamination from impurities in the reagents and the bicarbonate method leaves considerable amounts crf ammonium salts in even the most carefully washed beryllium basic carbonate. It is well known that beryllium salts hydrolyze with great readiness particularly on boiling. It seemed probable that the acetic acid slowly being formed by hydrolysis when the basic acetate is boiled in watcr, could be continuously removed by steam distillation. A weighed sample of the basic acetate was carefully steam distilled and the distillate analyzed. A theoretical yield of acid was recovered and the residual beryllium hydroxide produced was extremely pure and quite granular. Since the distillation method requires long periods for the preparation of small quantities of hydroxide, other methods of hydrolysis were tested. When collodion dialyzing flasks were used beryllium hydroxide was not precipitated and much beryllium ion migrated into the dialyzate before hydrolysis had progressed far. To hasten hydrolysis the collodion membrane containing the basic acetate solution was suspended in an atmosphere of steam, the acid perstilled readily and considerable hydroxidr precipitated in the membrane. Unfortunately such a container could not withstand the severe operating conditions and broke before the hydrolysis was complete. Separation of beryllium and acetic acid by electrolysis was tried. .It 6.4 A/dni2, using Pt sheet electrodes, gases were evolved very rapidly and the
THE CHEMISTRY OF BERYLLIUM
2469
solutions became heated to boiling. When the cells mere ice cooled, electrolysis proceeded smoothly. Large quantities of hydroxide were precipitated and migrated through the solution becoming moderately contaminated xvith carbon dioxide. The precipitate analyzed 73% beryllium oxide. Each of these methods produced an easily filtered and washed granular material that was of satisfactory purity for preparation of other beryllium salts. The beryllium hydroxide was converted to oxide by heating to redness in a platinurn crucible. Preparation of Anhydrous Beryllium Chloride The literature records several different' methods of obtaining the anhydrous chloride of beqdlium from the oxide. To form the anhydrouschloride, chlorine gas,' dry hydrogen chloride gas,' carbon tetrachloride vapor? and a mixture of chlorine and sulfur monochloridel have been passed over the heated oxide intimately mixed with a n excess of carbon as reducing agent. The residual carbon is very difficult to separate even by sublimation of the chloride which must he performed in a dry atmosphere or, better, in n vacuum. For the present work phosgene v a s the most convenient chlorinating agent available and several of the older methods have been repeated using this gas instead of the chlorinating agent employed by the original investigator. I n the first experiments sugar carbon was mixed ivith the dry beryllium oxide and phosgene passed over the mixture. If the phosgene were passed in rapidly or the tube strongly heated, the chloride was carried out by the waste gases and could not be recovered. Khen the temperature was carefully controlled and the chlorinating agent passed in slowly the chloride remained in the tube but was only difficultly separated from residual carbon. Carbon dioxide passed in with the phosgene served t o carry the beryllium chloride away from the carbon and the chloride condensed on the warm part of the tube at the end of the furnace. Since reduction of beryllium oxide by carbon proved so unsatisfactory a better method v a s sought. If a gaseous reducing agent could be used it \ ~ o u l dserve to carry the beryllium chloride along to the exit of the tube and could easily be separated from the chloride prepared. Since phosgene contained both reducing and chlorinating elements it was thought possible to perform the operation according to the following equation with phosgene only: COC12 Be0 = C O Z BeC12
+
+
For the successful preparation of anhydrous beryllium chloride the most important factor is the complete absence of water. Dry air was passed for several hours through a hard glass chlorination tube maintained at 4 jo', then dry phosgene to remove any possible impurity on the tube walls. Finally, the oxide, which had been heated to redness in platinum for some time, was l
Rose: Ann. Physik, 9, 39 ( 1 8 2 7 ) . Debra?: Ann. Chirn. Phys., (3j 44, 1-41 (1855). Meq-er: Ber. 20, 681 (1887); Camboulives: Compt. rend., 150, 173 (1910). Bourion: Conipt. rend., 145, 62 (1907).
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HAROLD SIMMOSS BOOTH AND GILBERTA G. TORREP
placed in the tube and dry air again passed through the tube until no trace of moisture was deposited on the cool end of the tube. Dry phosgene was then passed over the oxide a t 4 j0"C. and quantities of gleaming white needles of beryllium chloride formed. This method proved very satisfactory, readily producing large quantities of pure beryllium chloride. When carbon is used the considerable volume of the reacting solids fills the whole heated zone of the tube and only one plug of chloride is formed at the warm place where the tube leaves the furnace. With the phosgene method a small mound of oxide may be placed at one end of the tube near the COC12 inlet and the tube moved along through the furnace allowing successive plugs of chloride to form where the tube emerges from the furnace. Thus large quant'ities of chloride may be produced without opening the tube for removal of material and there is no danger of contaminating the sublimed chloride with residual oxide. At the close of a run dry air is passed through the tube until all excess phosgene is removed. To test the condensation of the chloride the excess phosgene and waste gases from several experiments were condensed, but on evaporation of the condensed gases no trace of beryllium material was found. Chauvenetl has shown the possibility of generally applying this method of phosgene chlorination and reduction to several difficultly prepared anhydrous chlorides. T o test the possibility of the forniation of a molecular compound? of anhydrous beryllium chloride and phosgene, liquid phosgene was condensed on some anhydrous beryllium chloride but without any sign of reaction. K h e n air-washed beryllium chloride was allowed to stand in a sealed vessel for several months no excess pressure was ever produced and no odor of phosgene has ever been observed from the chloride prepared with phosgene. Evidently no molecular compound is formed. Preparation of Beryllium Acetylacetonate Since beryllium acetylacetonate is not as readily hydrolyzed as most other beryllium salts it may be prepared3 by the action of acetylacetone directly on the moist beryllium hydroxide or basic carbonate. The beryllium material is slightly moistened with either acetic acid or water, a n excess of acetylacetone is added and the mixture allowed to stand over night. The beryllium acetylacetonate is extracted with absolute alcohol and the alcoholic solution evaporated in air. K h e n prepared by this method the beryllium acetylacetonate is colored faintly yellow or brown, probably due to some decomposition product from the acetylacetone. Beryllium acetylacetonate is also very difficultly separated from residual beryllium hydroxide or carbonate. The following method proved satisfactory. The beryllium hydroxide or basic carbonate is heated Chauvenet: Compt. rend., 152, 87 (1911). Baud: Compt. rend., 140, 1688 (1905). Parsons: J. Am. Chem. SOC., 26, 732 (1904).
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with water until pasty. A small portion of alcohol and an excess of acetylacetone are added and the mix left for 2 0 - 3 0 hours to crystallize. The crystals may be extracted with hot alcohol and the solution filtered to remove the major portion of residual hydroxide. After recrystallization from alcohol the acetonate is twice crystallized from chloroform. If the alcohol recrystallization is omitted a colloidal suspension of beryllium hydroxide in chloroform is produced and the brown impurity which is very soluble in alcohol is not removed. Considerable quantities of chloroform are occluded by the beryllium acetylacetonate. This may be removed by crushing and air-drying the crystals but is best removed by melting them on a platinum dish and heating gently until all chloroform is expelled. Preparation of Anhydrous Beryllium Nitrate Because of the high solubility and excellent conductivity of the resultant solutions of other nitrates the use of beryllium nitrate was considered. Beryllium nitrate crystallizes from water acidified with nitric acid as the tetrahydrate making it useless as an anhydrous solute. In order to eliminate the water, the direct union of metallic oxide and acid anhydride was attempted but without success. Anhydrous beryllium nitrate may be obtained’ by heating the hydrated nitrate with amyl alcohol. X saturated solution of hydrated beryllium nitrate in amyl alcohol is heated until vapors from the alcohol burn with a clear flame a t the mouth of the vessel. Masses of anhydrous beryllium nitrate are deposited from the alcohol solution on cooling but are difficultly freed from a film of alcohol and very readily absorb moisture on exposure to the atmosphere. A satisfactory method of dehydrating beryllium nitrate has been devised. Pure ammonium nitrate is carefully brought bo fusion and beryllium nitrate tetrahydrate added in small quantities. The melt is heated until no further odor of nitric acid is noticed. If the melt is heated very carefully only a small amount of decomposition of the ammonium nitrate occurs and the resultant melt is moderately stable. The melt may be poured out onto dry platinum and transferred to a vacuum desiccator as soon as cool without sign of decomposition. If left to st’and in air the anhydrous beryllium nitrate quickly absorbs moisture and the ammonium nitrate recrystallizes in the syrupy droplets of hydrated beryllium nitrate. Beryllium Potassium Chloride Parsons2 doubts that the double chloride of beryllium and potassium has ever been prepared, although H. L. \Tells3 has listed it in his series of double halides. In the hope of obtaining an anhydrous, double chloride, a mixture of beryllium basic carbonate and potassium chloride in approximately equimoleBrowning and Kuzirian: Orig. Corn. 8th Intern. Congr. .4pp’d Chem., 1, 87 “The Chemistry and Literature of Beryllium,” p. 47. Am. Chem. J., 26, 390 ( 1 ~ 0 1 ) .
(1912).
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HAROLD SIMMONS BOOTH AND GILBERTA G. TORRET
cular proportions was treated with concentrated hydrochloric acid. The solution was evaporated in an atmosphere of hydrochloric acid in a desiccator containing sulfuric acid. Our experience confirms Parsons’ opinion as only large crystals of potassium chloride were obtained when tlie solution evaporated and the mother liquid was a characteristic viscous mass. Beryllium Potassium Sulfate According to Ebelmanl beryllium oxide is very readily dissolved in fused potassium bisulfate. Khen first tried, the fused bisulfate produced an npparently clear glass with the theoretical portion of oxide. Careful examination showed that thc fine oxide particles merely remain suspended in the melt and do not react, but are invisible due to having the same index of refraction. Description of the Electrolyzing Apparatus The apparatus shown in Fig. z was devised for the electrolysis of the nonaqueous solutions of beryllium salts and modified from time to time t o suit the requirements of the individual solutions. The electrolyzing vessel, I’, shaped like a test-tube, was corinected to the rest of the apparatus through a conical joint, J, to facilitate rvmoval of t,hc tube for oven-drying and filling. Elcctrodcs, E, \wrc sealed in through the side arms and Jyere insulated from
FIG.2 : Compt.
rend., 33, 526 ( r b g I ) ; .J. prxkt. Chem., 5 5 . 342 i r S j z i
THE CHEMISTRY O F BERYLLIUM
2173
one another by a capillary glass sleeve not shown in the diagram. Platinum electrodes were used throughout the investigation. h short mercury manometer, M, was used to indicate the pressures approximately and when solutions were test'ed a t temperatures above those of room conditions, a thermometer, T, was shspended from a sealed joint a t the top of the central tube. In working with the non-aqueous solutions it was absolutely essential that every part of the apparatus be perfectly dry, hence the apparatus was dried by repeated rinsings with air dried by passage through the tube, D, containing phosphoric anhydride. Gases to be liquefied were condensed into an auxiliary ampoule, A, and condensed into the electrolyzing vessel as needed. In order to permit evacuation and subsequent preservation of a pure atmosphere of solvent vapor the entire apparatus was constructed of glass sealed at all joints except the conical joint, J, which was lubricated with special grease of low vapor tension. A low variable resistance and delicate milliameter to record the small currents employed, were kept in the circuit continually. A voltmeter was connected across the terminals of the cell only for short periods. Preparation and Purification of Solvents All solvents used were suitably purified, carefully dried and usually fractionally distilled. Et h yl bromide was kept over calcium chloride for several days, decanted and filtered, and fractionally distilled. The main portion of the ethyl bromide distilled over at 345-36OC. while another sample kept over phosphoric anhydride distilled uniformly at 3 7 .j-39'C. Selenium oxychloride was vacuum distilled' with a calcium chloride tube in the system to protect the liquid from the vapors of the suction pump. The portions used in electrolyses were obtained by distilling the oxychloride under partial vacuum directly into the electrolyzing vessel. Phosgene was purified by bubbling it through sulfuric acid and condensing it with ether-carbon dioxide mixture. Chloroform was kept over calcium chloride for several weeks and then fractionally distilled. Acetylacetone was distilled immediately before use. Likewise phosphorus trichloride was fractionally distilled before use. Freshly opened, pure samples of glacial acetic acid and absolute alcohol were used without any special treatment. A sample of molecular compound formed by methyl ether and boron triJEuoride was furnished by Dr. A. F. 0. Germann2 and was redistilled before use. Sulfur dioxide was used just as it came from a commercial tank of gas under pressure. Experimental Solutions in Ethyl Bromide. The work of Plotnikoff and Patten with solutions of aluminum bromide in ethyl bromide suggested the use of ethyl bromide as an electrolytic solvent for beryllium compound^.^ Beryllium bromide was not available but beryllium chloride was found to dissolve in I.
J. Am. Chem. SOC., 43, 30 (1921); 44, 1664 (1922). Science, 53, 582 (1921); Chem. Abs., 16, 3796 (1922). References cited under choice of solvents.
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HAROLD SIMMONS BOOTH AND GILBERTA G . TORREY
considerable amounts in ethyl bromide. Save for a gas a t the cathode the filtered solution gave no electrode products. The highest current density obtainable with a I I O volt potential was . I 7 5 amperes/sq. dm. A few crystals of sodium trinitride were added in an attempt to form the beryllium trinitride from which the metal might be deposited but there was no apparent result except the lowered conductivity of the solution. I t is possible that a complex compound was formed between the ethyl bromide and the beryllium chloride which would account for the very marked solubility of the beryllium chloride. Gustavsonl states that a solution of aluminum bromide in ethyl bromide on heating evolves hydrogen bromide and saturated hydrocarbons leaving a complex aluminum bromide hydrocarbon. Even on mere solution of beryllium chloride in ethyl bromide vapors of a very penetrating odor, which gave a test for halogen with silver nitrate, were evolved. On standing crystals of a form entirely different from that of beryllium chloride separated and floated on the surface of the solution while beryllium chloride itself falls directly to the bottom. The extreme hygroscopicity of the solution made a determination of the solubilitv of the beryllium chloride almost impossible. By careful manipulation an approximate value was obtained indicating that the solubility approached three per cent. X sample of solution v a s rapidly weighed in a crucible and evaporated slowly in an oven a t 90°C. The crystalline residue was transparent, only slowly attacked by moisture of the air, dissolved in water with hissing and evolution of gas of a pungent odor. 2. Solutions in Methyl ether-Boron fluoride. The liquid, molecular compound formed by the combination of the two gases, methyl ether and boron fluoride, was found to have moderate solvent action on several beryllium compounds. From analogy with the action of calcium fluoride and boron fluoride which form a series of Huoborates,' it seemed possible that a fluoborate, Be(BF4)*,or a derivative might be formed by the action of boron fluoride on beryllium salts. Portions of the liquid compound were placed over beryllium-sodium fluoride, beryllium chloride and beryllium acetylacetonate and left for several days to become saturated. A portion of the pure solvents was electrolyzed as a blank to determine the conductivity, electrode products, and behavior of the methyl ether-boron fluoride alone. On a four-volt circuit the pure solvent carried one ampere/sq. dm. wit,h a potential across the cell of 3.45 volts. A very small amount of gas was observed at the cathode but no visible anode product. With higher voltage the temperature increased and the conductivity improved. At the higher temperatures bubbles of gas appeared at both electrodes but since no increase of pressure was observed the bubbles were doubtless boiling solvent. a. S o d i u m beryllium fluoride. The use of sodium-beryllium fluoride as a fused electrolyte suggested the use of this salt as a solute. Unfortunately, however, this salt was found to have little, if any, solubility in this solvent J. prakt. Chem., ( z ) , 34, 16; (1886:. work of the junior author
* Unpublished
THE CHEMISTRY OF BERYLLIUM
2475
and electrolysis of the liquid which had stood over the solid salt gave no electrode products. b. Beryllium chloride. Solutions of this salt gave fair conduction on an eight-volt circuit. At the beginning of a run the conduction was usually about 2.8 amperes/sq. dm. but slowly and steadily dropped to a uniform value of one ampere/sq. dm. where it remained for the whole period of a run. The potential difference a t the latter value was 3.8 volts. A little gas was always produced a t the cathode and may have been the source of the small back E M F . that was always observed a t the end of a run. A black, amorphous, adherent material, insoluble in hydrochloric acid was produced a t the cathode from which it could be removed only with difficulty. c. Beryllium acetylacetonate. This salt is very soluble in methyl etherboron fluoride but the solution does not conduct well. Only three amperes/sq. dm. were carried a t a potential of I O volts. Gas was evolved a t the cathode and a black material, insoluble in hydrochloric acid, adhered to the cathode. At the anode a brown coloration was produced which eventually colored the solution a deep cherry-red. 3. Solutzons in Ethyl Alcohol. In other experiments with fused salts of beryllium it was observed that the conductivity was improved if traces of alcohol had been left on the recrystallized salts. This suggested the use of ethyl alcohol as a non-aqueous solvent. Beryllium acetylacetonate is quite soluble in alcohol from which it may be recrystallized without decomposition. The saturated solution conducts fairly well but much gas is produced, the temperature increases rapidly and no metal is deposited on the cathode. 4. Solutions in A m y l Alcohol. The saturated, anhydrous solution of beryllium nitrate in amyl alcohol is very viscous1 and does not conduct well. On warming the solution in a water-bath to lower the viscosity so muchalcohol bubbles off that no observation of possible electrode gases can be made. No metal was deposited on the cathode but the electrode was covered with white crystals of anhydrous beryllium nitrate. These crystals are perfectly stable in the amyl alcohol solution but rapidly absorb moisture on exposure to air. 5 . Soluttons zn Glacial Bcetzc Acid. Beryllium acetylacetonate is soluble in glacial acetic acid but the presence of the elements of water in this solvent did not favor its use as solvent. The solution only carried .145 amperes/sq. dm. with I I O volts potential difference. A gas was evolved a t the cathode and a white, crystalline material was deposited in the region of the anode. It was possibly di-acetylacetone. 6 . Solutions in Acetylacetone. Beryllium chloride dissolves in acetylacetone without decomposition and the solution conducts fairly well while acetylacetone alone is a non-conductor. A gas is evolved a t the cathode and a white crystalline material was deposited at the anode.? The precipitate was soluble in water and was possibly di-acetylacetone. No deposition of metal was observed. Browning and Kuzirian: Orig. Cam. 8th Intern. Congr. Appl. Chem., 1, 87 (1912). R. yon Schilling and D. Vorlander: Ann., 308, 199 (1899).
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HAROLD BIMMONS BOOTH AND GILBERT.4 G. TORREY
7 . Solutions in Phosgene. The possibility which has been suggested of beryllium chloride forming a molecular compound with phosgene similar to the solid phosgenate of aluminum chloride or the liquid addition compounds with magnesium chloride encouraged a trial of this mixture.* Dry phosgene was condensed over pure anhydrous beryllium chloride but the chloride showed no apparent solubility. The liquid over the beryllium chloride carried only .o2 j amperes/sq. dm. at 110 volts potential and gave no noticeable electrode products. The phosgene readily evaporated on warming with no sign of reaction. 8 . Solutions in S el en i u m Oxychloride. This compound seemed to have possibilities because of its solvent power and its property of converting metallic oxides into chlorides by mere contact without heating. A sample of selenium oxychloride was distilled directly into the electrolyzing vessel on to a sample of dry beryllium oxide. The beryllium oxide displayed no definite tendency to solution but became gelatinous and fluffy. Water was added t o a sample of this gelatinous material and it was found to dissolve readily, probably because of conversion to beryllium chloride. The selenium oxychloride which had stood over the heryllum oxide was electrolyzed and carried 30 amperes/sq. dm. on a I O volt circuit. The temperature rapidly increased to 8o°C. and much gas was evolved a t the anode. A red coloration rapidly spread through the solution from the anode and was later proved due to platinum tetrachloride. S o electrolytic products were observed a t the cathode.
In the course of another ex9. So2utions in P h o s p h o ~ u s T,ichloride. periment it was observed that beryllium acetylacetonate was extremely soluble in phosphorus trichloride. The saturated solution, however, was non-conducting on either I O volt or I I O volt circuits. IO. Solutions in L i q u i d Sillfur Dioxide. Other investigators have found that many salts formed solutions in liquid sulfur dioxide and t h e solutions were fair conductors of electricity.? Fused beryllium acetylacetonate was warmed in the electrolyzing vessel under vacuum to remove traces of chloroform and dry sulfur dioxide passed in. The beryllium salt was very soluble in the liquid sulfur dioxide, but the solution even in a I I O volt circuit was absolutely non-conducting.
Conclusion Several compounds of beryllium have been prepared in a high degree of purity. Xew methods of preparation have been developed and older methods improved. Certain mis-statements in the literature have been I.
1 Baud: Compt. rend., 140, 1688 (1905); Germann and Timpany: J. Phys. Chem., 29, 1423, 1469 (1925); Germann and Gagos: J. Phys. Chem.. 28, 965 (1924). Bagster and Steele: Trans. Faraday Soc., 8, 5 1 (1912); Kraus and Bray: J. Am. Chem. SOC., 35, I31 j (1913).
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2177
corrected. A s this work has only been preliminary to the research on the preparation of metallic beryllium much of the work has not received the complete treatment that would be desirable but is included as a suggestion to future workers in this field.
h variety of beryllium salts have been dissolved in non-nitrogenous 2. non-aqueous media and the behavior of the solutions on electrolysis observed. The majority of the solutions conduct electricity very poorly and none have been satisfactory sources of metallic beryllium.
