1,596,119 Patented Aug. 17, 1926. UNITED STATES PATENT OFFICE. ROBERT w. POINDEXTER, JR, OF LOS ANGELES, CALIFORNIA, ASSIGNOR TO CALIFOR NIA CYANIDE COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE, PROCESS FOR MAKING CALCIUM CYANOGEN COMPOUNDS AND THE PRODUCT BIEREOF. Application filed February 18, 1926. Serial No. 89,224. No Drawing. method of preparing the solid cyanides of the S5 This invention relates to an improved method of producing solid cyanogen com weaklyI am basicaware metals. that a method of producing pounds of the alkaline earth metals and to a calcium cyanide which consists in treat the product thereof. ing calcium carbide with hydrocyanic acid As is well known, the cyanides of metals has been discovered by Floyd J. Metzger. 60 forming strongly basic hydroxides such, for The calcium cyanide product which results example, as sodium and potassium, may be from carrying out my process is similar in produced readily by causing such hydroxides many ways to that prepared by the Metzger to react with hydrocyanic acid in aqueous process from calcium carbide. It is differ 85 10 Solution, and then evaporating the solutions entiated from the latter in that it contains to obtain the corresponding cyanides in a variable amount of alcohol of combination. solid form. Even in the case of the cyanides The process which I have discovered, how of such strong bases, the solutions obtained ever, is entirely distinct from that of Metz by the reaction are evaporated preferably ger in that it starts with entirely different 70 15 in a vacuum because the cyanide compounds calcium compounds, namely, calcium oxide tend to decompose when the solutions are or, calcium hydroxide in place of the cal evaporated at atmospheric pressure. In cium carbide used by Metzger, thus substi such solutions, the decomposition consists tuting cheap and easily obtainable raw ma principally in the hydrolysis of the cyanide terials for the more expensive calcium car 5 20 to ammonia and the formate of the corre sponding metal. Aqueous solutions of the bide.The fact that my cyanide w product con cyanides of the alkaline earth metals of which the hydroxides are weaker bases than tainsvent itsalcohol being of employed combination for doesthose notuses pre to the hydroxides of sodium and potassium, which calcium cyanide is usually applied. 80 25 may be produced by reacting on the corre In particular, my product possesses the sponding hydroxides in aqueous solution. property, which will later be described in When, however, evaporation of such soluia detail, of evolving hydrocyanic acid freely tions is attempted, even under a high vacu and copiously when exposed to the atmos um, the cyanides usually decompose into free phere. This property makes it extremely 85 30 hydrocyanic acid and the hydroxide of the valuable for the purpose of fumigation, for corresponding metal. For example, in the the control of all sorts of insect and animal case of calcium, water enters into this re pests. Since it is stable so long as it is ex action as shown by the equation: cluded from contact with the atmosphere, it may be stored and transported readily and 90 35 Ca(CN), +2HO-Ca(OH) +2HCN. safely. When applied to plants in thin Thus, a dilute solution of calcium cyanide layers or by dusting into the atmosphere, or may be prepared readily by treating an when similarly applied in enclosed spaces aqueous suspension of calcium hydroxide which it is desired to fumigate, the prod with hydrocyanic acid. The calcium hy uct of the process which I have discovered rapidly evolves nearly its entire cyanogen 95 side goes into solution as calcium cya content in the form of hydrocyanic acid. Cle. The great value of calcium cyanide pro Ca(OH)4-2HCN-Ca(CN), +HO duced by my process for the most varied but on evaporating such a solution, the kinds of fumigation is thus apparent, as is 00 45 hydrocyanic acid distills off, leaving a sus also its superiority over liquid hydrocyanic. pension of calcium hydroxide in water, even when the evaporation is conducted under a wellacid knownfor similar hazard purposes in storing on accountand transport of the vacuum. This fact is already well known ing the latter. o w and described in the literature, as for in When either calcium oxide or calcium 105 80 stance, in “The Chemistry of Cyanogen hydroxide is suspended in a substantially Compounds” by Herbert E. Williams, page. alcohol,anhydrous and alcohol, substantially such as anhydrous methyl or hydro ethyl 42. cyanic acid is added to such a suspension, provideIt is the new object cyanogen of the present products invention and toa 1,596,119 the calcium hydroxide almost immediately hydrocyanic acid, for the purpose of remov dissolves, yielding a clear solution of calcium ing alcohol adhering to it. The product cyanide. prepared as described is a light, fluffy crys talline powder. In color it may be white, If evaporation of such a solution is at cream color, buff or light brown, depend 0 . tempted, even under a vacuum, the solution ing on the conditions used in its prepara darkens rapidly, becoming dark brown or tion. I believe the color of those batches nearly black. As the evaporation is con which are not white to be due to the pres 0. ence of polymerized hydrocyanic acid. If tinued, a residue is obtained, consisting of a the process has been carefully carried out, 75 nearly black gelatinous mass. The dark ma and in particular if it has been conducted terial thus prepared contains but little cyan rapidly, the product, after drying, will be ogen, in all cases less than that correspond white. 5 ing to the formula Ca(CN), having lost All batches of the product which I have most of its original cyanogen content either thus far prepared contain, in addition to cal 80 through liberation as freehydrocyanic acid, cium cyanide, more or less of the particular polymerizationor through such of theliberation hydrocyanic followed acid, by alcohol used in the process. The amount of I have discovered that excellent products alcohol present has been found to vary with 20 may be obtained, nevertheless, by treating the conditions used in this preparation. The such alcoholic solutions of calcium cyanide calcium product has, therefore, the approxi with an excess of hydrocyanic acid. Cal mate formula cium cyanide is less soluble in hydrocyanic acid than in methyl or ethyl alcohol and Ca(CN).xR(OH), 25 consequently the addition of excess hydro R being the radical of the alcohol used in cyanic acid causes a precipitation of calcium preparing the product. The invention com cyanide. The precipitate may readily be prehends the substitution of other metals of dried, since the mixture of alcohol and hy the alkaline earth group, including barium drocyanic acid adhering to it is quite vola and strontium, for the calcium, forming 30 tile. compounds of the general formula In all cases I have found it possible to 9. use calcium hydroxide in place of calcium oxide in carrying out my process. Pure cal where M indicates the metal. The presence 35 cium compounds may be used but the proc of alcohol, even after thorough drying in ess can be carried out with the commercial products prepared in this general manner, 0. grades of calcium oxide and calcium hydrox may be shown by dissolving the dry mate ide. The following equations illustrate the rial in a solution of sodium hydroxide. The materials:reactions involved by the use of these two sodium hydroxide reacts with the calcium 40 cyanide to produce calcium hydroxide and sodium cyanide. On distilling the resultant 105 tillate.mixture, alcohol may be identified in the dis It is thus apparent that in case calcium hy The chemical composition of the product droxide is used, twice as much water will be is subject to a slight variation. This varia 45 formed. This will produce a slightly greater tion in composition appears to depend on the dilution of the reaction mixture, but this () does not very materially affect the produc conditions prevailing during its manufac tion of the desired calcium cyanogen com ture. This, however, does not affect its use pound in carrying out my process. The term fulness for the purposes for which calcium 50 oxide' as used in the claims hereinafter in cyanide is or maybe employed, since the cludes the hydrated oxide or hydroxide. variation is only slight. The following ta 5 The product will normally contain the in ble indicates the results of variation in com purities such as silicia, iron, alumina sili position which may be expected. cates, etc., which are present in the calcium 55 oxide or hydroxide. These impurities are E.re insoluble, however, in the alcohol solution Run No. Pesent PSnt E. 120 and can be removed by filtering before the (by dif excess of hydrocyanic acid is introduced to forence).

l------26, 9 40, 9 32.2 60 precipitate the calcium cyanide. It is pos 2- 26.3 43.2 30.5 sible, therefore, to produce calcium cyanide 3. 27.6 45.2 27.2 4- 27.6 43.5 28.9 25 substantially free from impurities by fol 5-- 27.9 44.6 27.5 lowing the procedure indicated. 6. 26.8 42.7 30.5 7. 27.5 49.4 23, , If a pr uct of good color and purity is 8- 28.2 44.6 27.2 9. 27.2 42.3 3.5 wanted, it is desirable, though not essential, 10---- 27.3 49.4 23.3 SS 1l------23.8 40, 0 33.' to wash the precipitate, before drying, with 30 1,596,119 44.6%. The difference between the sum of The product is stable when not exposed to these percentages, (27.2%) was assumed to the atmosphere, but when exposed to the at consist chiefly of methyl alcohol, but the mosphere it evolves hydrocyanic acid and alcohol content was not determined by anal alcohol. The evolution of these substances, ysis. Ethyl alcohol may be substituted 70 on exposure to the atmosphere, is so rapid for methyl alcohol in the process without that the evolved vapors may be ignited, in any way affecting it. It will affect the when they will burn with a flame. When ex product to the extent that the latter will posed to the atmosphere in thin layers, contain ethyl alcohol of combination in nearly all of the cyanogen content of the ma place of methyl alcohol of combination. 5 10 terial is evolved in the form of hydrocyanic This change is entirely immaterial for any acid, leaving a residue consisting essentially of the uses to which calcium cyanide is usu of calcium hydroxide. If the residue is ex ally put. Similarly other alcohols may be posed to the air for a sufficiently long period, used in place of either ethyl or methyl al it will eventually become converted to cal cohol. The former, however, are to be pre SO 5 cium carbonate by absorption of carbon di ferred on account of their lower cost. oxide from the atmosphere as would be ex The operation as described affords a re pected from any specimen of calcium hy liable and relatively inexpensive process for droxide so exposed. The calcium cyanide producing solid cyanide compounds of the product which I have discovered is readily alkaline earth metals, and various changes SS 20 soluble in water, in methyl alcohol, or in ethyl alcohol. The solutions thus produced can be made in the details thereof without show the usual reactions for calcium and departing from the invention or sacrificing cyanogen ions. The color of such solutions, the advantages thereof. when first prepared, corresponds to the color 1.I claim:-The process of producing solid cya 9. of the dry material used in their preparation, but when allowed to stand such solutions nides of the alkaline earth metals, which tend to darken in color on account of the consists in treating a mixture of the oxide formation of hydrocyanic acid polymer. of the metal and a monohydric alcohol with To more clearly indicate the preferred an2. excess The ofprocess hydrocyanic of producing acid. solid cya 95 30 method of producing calcium cyanide by the process which I have discovered, I give the nides of calcium, which consists in treating following specific example: a mixture of calcium oxide and a monohy Six grams of high grade, commercial, dis alcohol with an excess of hydrocyanic powdered calcium oxide was placed in a ClO.3. The process of producing a solid cyan 35 beaker and 40 c.c. of substantially pure, ab ogen compound of an alkaline earth metal, solute methyl alcohol added. This mixture which consists in forming an alcoholic solu was stirred vigorously, so as to keep the cal tion of the cyanide of the metal by treating cium oxide in suspension, while 10 c. c. of a mixture of the oxide of the metal and a substantially anhydrous liquid hydrocyanic monohydric alcohol with hydrocyanic acid acid was added. The reaction between the and then adding an excess of hydrocyanic hydrocyanic acid and the suspended calcium acid to precipitate the cyanogen compound. oxide was almost instantaneous and was ac 4. The process of producing a solid cal companied with considerable ebullition, due ciulin cyanogen compound, which consists in O to evolution of heat. The calcium oxide forming an alcoholic solution of calcium cy 45 dissolved quite completely, resulting in a anide by means of treating a mixture of cal nearly colorless solution. 70 c. c. of anhy cium oxide and a monohydric alcohol with drous liquid hydrocyanic acid were then hydrocyanic acid and then adding an excess added to the solution, resulting in a copious of hydrocyanic acid to precipitate the call white precipitate. The mixture was filtered cium cyanogen compound. through filter paper supported on a Hirsch 5. The process of producing a solid cyano vacuum funnel, with the use of suction by gen compound of an alkaline earth metal, vacuum to hasten filtration. The precipi which consists in forming an alcoholic solu Late was washed with 30 c. c. of anhydrous tion of the cyanide of the metal by treating 20 liquid hydrocyanic acid. The suction was a mixture of the oxide of the metal and a 55 continued about one minute, in order to re monohydric alcohol with hydrocyanic acid, move as much excess hydrocyanic acid as adding an excess of hydrocyanic acid to pre possible. The precipitate was then quickly cipitate the cyanogen compound and wash transferred to a 150 c. c. Erlenmeyer flask. ing the precipitate with hydrocyanic acid. The flask was placed in a large beaker of 6. The process of producing a solid cal 60 water, heated to 30° C. and a vacuum main cium cyanogen compound, which consists in tained at 26' was applied to it for a period forming an alcoholic solution of calcium cy of one hour. The dried product was white anide by means of treating a mixture of in color and was in a very fine state of sub calcium oxide and a monohydric alcohol division. Analysis showed: with hydrocyanic acid, adding an excess of 5 Calcium (Ca) 28.2, cyanogen (CN) 14 1,596,119 hydrocyanic acid to precipitate the cyano gen compound and washing the precipitate 9. A solid cyanogen product containing a with hydrocyanic acid. metal of the alkaline earth group and hav 7. The process of producing a solid cyano ing the formula 25 gen compound of an alkaline earth metal, which consists in forming an alcoholic solu M(CN).xR(OH). tion of the cyanide of the metal by treating 10. A solid calcium cyanogen product a mixture of the oxide of the metal and a having the formula monohydric alcohol with hydrocyanic acid, 30 O adding an excess of hydrocyanic acid to pre Ca(CN).xR(OH). cipitate the cyanogen compound, washin 11. A solid cyanogen product comprisin the precipitate with hydrocyanic acid an a cyanide of a metal of the alkaline eart drying the precipitate. tion.group with monohydric alcohol of combina 8. The process of producing a solid cal 35 15 cium cyanogen compound, which consists in 12. A solid calcium cyanogen product forming an alcoholic solution of calcium comprising calcium cyanide with monohy cyanide by treating a mixture of calcium dric alcohol of combination. oxide and a monohydric alcohol with hydro 13. A solid cyanogen product capable of cyanic acid, adding an excess of hydrocyanic decomposing upon exposure to an atmos 40 20 acid to precipitate the cyanogen compound, phere to release hydrocyanic acid and a washing the precipitate with hydrocyanic monohydric alcohol. acid and drying the precipitate. In testimony whereof I affix my signature. ROBERT W. POINDEXTER, Jr.