Patented Dec. 7, ‘1948 2,455,895 '5 UNITED STATES’ Paired-1T OFF-ICE -' ‘ - I -'2‘,45s,s95, d‘ _ _> “ ~ ' I PREPARATION 0F 'ME'rALfsAL'rs ' p ' DICYANIMIDEK: a. z. t /. ~. Daniel E.~Nagy and Bryan (1RedmonfStamford,vv Conn., assignors to American Cyahamid Com pany, New York, N. Y‘., a corporation of Maine No‘ Drawing. ’ Application September" 22, ‘1945; ' " j Serial No.618,'071' ' " t' ‘ - 7 claims. (01. 23-75) .‘The present invention relates to a method for ‘S ‘ Typical substantially insoluble copper salts are: preparing alkali metal salts of dicyanimide'and Cupric hydroxide ,'_ .Cupric tartrate to these salts which are new compounds. Cupriccarbonate.‘ ,_ . ‘ Cupric sul?de ‘Inparticularthe ‘present invention contem Cupric oxalate , ‘ Cupric arsenate, plates the reaction of a dicyanimide salt of a metal .; ' Cupric phosphate _ Cupric ferrocyanide chosen 'from the [group consisting of calcium, copper," and zinc, with an alkali metal salt, the Typical substantially insoluble zinc salts are: anion portion of which forms a substantially Zinc hydroxide Zinc selenide insoluble inorganic salt of calcium, copper, or Zinc carbonate Zinc telluride zinc; The general reaction is given by Equation 1-. 1.0 Zinc oxalate Zinc arsenate Zinc phosphate Zinc ferrocyanide i/il-N ' + Ax --->_ I A-—N\: + NlX ' In particular, the present invention contem platesthat anvalkali metal dicyanimide may be where A is anON alkali metal, M is ‘0Na vmetal chosen prepared by‘the reaction in water of a metal from the group consisting of calcium, copper, and dicyanimide'and an alkali ‘metal salt, the anion zinc,- and AX is an alkali metal salt whose anion portion of which will combine with and precipi portion, X, forms a substantially’insoluble salt tate the cation» or metal attached to the afore withM. ‘ mentioned metal‘ dicyanimide, so that it may " Typical examples of the alkali metal salts suit easily be separated’from the'resulting alkali metal able for carrying out the present invention are: dicyanimide. ; a 3 \ . Sodium hydroxide Trisodium phosphate Example 1 _ Lithium hydroxide Tripotassium phosphate The, taqueoustyt-suspension of zinc ’ dicyanimide Potassium hydroxide Disodium phosphate 25 is prepared and 20% aqueous potassium hydrox Sodium carbonate Dipotassium phosphate ideris added thereto?until the pH ofithis agitated Potassium carbonate Sodiumtartrate mixture ‘remains at. 8-9. The substantially insol Sodium bicarbonate Potassium tartrate uble zinc hydroxide is removed by ?ltration and Lithium‘ bicarbonate , Sodium tungstatet the ?ltrate isneutralized with a few drops of Potassium bicarbonate Potassium tungstate ' 30 llli%;_hy_drochl_oric acid.‘ ;This neutral ?ltrate is Sodium sulfate Sodium sul?de then concentrated under reduced pressure until Lithium sulfate ‘ } Lithium sul?de crystals of potassium dicyanimide start to form, Potassium sulfate > ' Potassium sul?de at which time the residue‘is diluted with acetone Sodium sul?tee Sodium selenide H or isopropanol. This treatment causes additional sul?te Potassium ~ selenide ' crystallinepotassium. dicyanimide .to ‘form, and Potassium sul?te Sodium telluride after recovery, puri?cation, and drying, the color Sodium ?uoride } Sodium arsenate , lessacrystallinepotassium dicyanimide melts at Potassium arsenate Potassium ?uoride 228° ‘C. c , , » , - ' Sodium oxalate Sodium ferrocyanide I Lithium oxalate Potassium‘ ferrocyanide 40 I _ ’ Example 2_ I Potassium oxalate By following the _ generalprocedure outlined in the above, potassium dicyanimide is also prepared Similar soluble salts of cesium and rubidium by the interaction“ of" “substantially stoichio may also be used. The anion'portion ofthe afore metricamounts of potassium carbonate and zinc mentioned salts gives a precipitate with' one or dicyanimide. , The crystalline solid obtained byv more of- the three cations, calcium,'copper, and this‘ method melts at‘ the same point as that zinc. ’ ‘ Typical-substantially insoluble salts of calcium recordedabove. > t are: I ~ g _ j Example 3 Calcium hydroxide Tricalcium phosphate 50 Potass'iumdicyanimide also prepared by the Calcium carbonate Dicalcium phosphate interaction of aqueous potassium hydroxide with Calcium-sulfate V Calciumtartrate » copperdicyanimida The colorless crystalline po Celqium sul?te Calcium vtungstate tassium dicyanimide obtained by the method is Calcium ?uoride Calcium arsenate ‘ identical with that obtained by'the methods in-~ Calciumjoxalate \, H I 55 dicated above;- ' .. t. .~ 2,455,895 3 4 Example 4 tion, and the aqueous ?ltrate containing both sodium chloride and sodium dicyanimide is con An aqueous slurry of zinc dicyanimide is made centrated. When the water removal progresses alkaline with aqueous sodium hydroxide until the to such a point that the concentration of the pH of the agitated reaction mixture remains at sodium chloride is 25%—35%, the sodium cli 8-9. The. zinc hydroxide is ?ltered andthe fil cyanimidereadily crystallizes and‘ is recovered. trate obtained therefromis evaporatedto; dryness It has physicaljproperties identical‘ with those to yield colorless crystalline sodium dicyanimide reported above. which does not melt up to 315° C. 1 i _ The aforementioned examples illustrate the In order to characterize this solid, the optical 10. several ways in which alkali metal dicyanimide and crystallographic propertiesi‘are' described. '' ‘ may ‘be prepared and recovered. Sodium dicyanimide crystallizes as lamellar- plates 'The'alkali metal dicyanimides of the present and has a positive optic sign. The. principal ree invention. are, valuable chemical intermediates fractive indices as observed in. white light are as; and; sources of‘ dicyanimide which may be used follows: a=l.410:0.0D3; in. the preparation of pharmaceuticals, chem The apparent optic axial angle as observed in air otherapeutic agents, insecticides, dyes, plastics, is 86°, and the true optic axial anglecomputed' resins, and‘the like. therefrom is 55°. ‘ ' ‘ ' While the invention has been described with Example 5 particular reference to speci?c embodiments, it 20 is to be understood that it is not to be limited Substantially, stoichiometric. amounts. of zinc thereto_.;but is to be construed broadly-1 and‘ re dicyanimide and aqueous sodium carbonate ‘react stricted solely by the scope of. the appendedjclaims. to form substantially insoluble zinc‘ ‘carbonate What is; claimed: which is removed by ?ltration; The‘ resulting . 1. A~.method of preparing an alkali; metal: salt ?ltrate is-evaporated to dryness and’ yields sodium 25 of dicyanimideiwhich includes the stepsiofi react: dicyanimide having the above mentioned physical ing in water a dicyanimide salt of.‘ a metal chosen p-roperties.- Substitution. or: sodium;- bicarbonate fromthe group consisting of calcium, .coppeniand for sodium carbonate gives equally satisfactory zinc with-an alkali-metal salt, the ‘anion: portion results in the preparation of sodiumdi'cyanimide oi which forms agsubstantially waterinsolublmma from zinc dicyanimide, " ‘ ' 30 organic. salt of a metal. chosen from the.‘ group Example 6 .. consisting of. calcium, copper, and zinc, to pro duce an alkali metal dicyanimide, and removing Sodium dicyanimide is also prepared‘; by" the the aforementioned‘substantially water insoluble action of aqueous‘ trisodium; phosphatev on zinc inorganic salt from the alkali metal dicyanimide. dicyanimide. A 20% trisodium phosphatesolu 35 . 2.. A. methodo? preparing an» alkali metallsalt tion is added to anaqueous slurry of zinc vdi- of dicyanimidewhich includes the steps ofireaet cyanimide until the pH remains at 8-9; ,‘I‘hev sub-T. ingin water a- dicyanimide salt of a metal chosen! stantially insoluble... zinc.» phosphate is removed from .the group consisting , of calcium, copper,; and and the sodiumdicyanimide is-recoverediby con zinc with an alkali metal salt, the anion portion centration of this ?ltrate-and its: physical prop: of- which. forms a. substantially. water insoluble erties arethose already mentioned. inorganic. salt of. a. metal. chosen from.- the,‘ group Example 73 consisting of calcium, copper, and ‘zinc, to pro duce} an: alkali; metal dicyanimide,- removin-g; the Substantially stoichiometric amounts of an aqueous solution’ of calcium‘ dicyanimide» and"25%. aforementionedhsubstantially water insoluble in'~'~ sodium hydroxide are mixed and thoroughly’ agi 45 organic‘ salt from the alkali‘ metal dicyanimide; tated. The calcium hydroxide thus: precipitated and. recovering the alkali metal? dicya-ni'mi‘d'e;v is ?ltered and- Washed free of any: sodium ‘dié 3. Thehmeth'odf-of claim 2 ‘in which‘ the‘ alkali cyanimide. Thecombined ?ltrate and washings metalis sodium. ' v are evaporated to‘ dryness to yield-_ sodium dif-Q 4. The : method: of ‘claim 2 in‘ whiclr- the" alkali; cyanimide having physical~~ properties identical metal isf'potassium'. 5. A methodo?preparing sodiumdicya-nimide' with‘ those mentioned in»Example'4=. ” ' ' which includes‘ the‘ steps of reacting in Water‘ a Emample?. dicyanimide salt ofialmetal chosen from the group? The substitution of i sodium‘ carbonate and/or’ consisting off calcium,v copper, and3 zinc with“ a; sodium sulfate for the. sodium hydroxideaboye sodium carbonate to- form a substantially-‘water mentioned will‘ precipitate either calcium car-'4 insoluble» carbonate and solublev sodium'i: dif-. bonate .or calciumlsulfatelwhich. can berremovedi cyanimide,~='removing' the thus formed‘ substam from the presence of the aqueous sodium 'dié tiallyjwater insoluble carbonate‘ from-the aqueous cyanimide. The latter-maybe recovered