Patented May 10, 1927. 1,628,380 UNITED STATES PATENT OFFICE. FRANK WILCOXON, OF ITHACA, NEW YORK, AND BENNETT GROTTA, or TAMAQUA, PENNSYLVANIA, ASSIGNORS TO ATLAS POWDER COMPANY, OF WILMINGTON, DEL AWARE, A CORPORATION OF DELAWARE. PROCESS FOR THE MANUFACTURE OF SODIUM AZIDE. No Drawing. Application filed October 27, 1924. serial No. 746,247. Our invention relates particularly to an highly concentrated hydrazine solutions and , 55 improvement in the manufacture of sodium Sodium ethylate instead of sodium hydroxide azide, the Salt of hydrazoic acid which is Solutions. in this process Sodium azide pre commonly employed as a raw imaterial for cipitates Out of Solution and may be isolated 5 the production of other derivatives of hydra by filtering from the mother solution. Zoic acid, such as, for instance, the heavy It is apparent that each of the above modi 60 metal azides which are used in detonator fications has merits not possessed by the compositions. Other. In the first, less costly raw materials Soon after it was discoverel that hyd'a- are employed, but there is the necessity of O Zoic acid could be produced by the action of isolating the azide by distillation of hydra nitrous acid on benzoyl-hydrazine, it was Zoic acid, an operation which is usually con 65 found that the reaction could be effected be sidered hazardous and which always involves (ween hydrazine derivatives other than the loss of the product involved. In the latter, benzoyl compound and variots derivatives of the Sodium azide may be isolated by simple nitrous acid, in accordance with the follow filtration but it is necessary to employ sodium ing type equation: ethylate which, in turn, requires the use of 70 letallic sodium, a comparatively costly in NH-i-HNO-HN-|-2H (3. gi'edient the handling of which also involves A mong the Various processes that ilave considerable hazard. 2. been proposed for the production of hydra in our efforts to devise a process in which zoic acid or its derivatives is the reaction be Would be incorporated the merits of the two 75 tween hydrazine or its Salts and an alkyl above mentioned modifications and having nitrite in an alkaline Solution. O in conduct the deficiencies of neither, we have made the ing an extensive study on this process. We discovery which is the basis of this patent 2. 5 have found that two distinct inodifications of application. this reaction are disclosed. These are as fol We have found that excellent yields of so 8) lows: dilian azide may be obtained with ease by (a) The use of non-anhydrous 'eaction bringing together in suitable proportions mediums. and proper concentrations hydrazine hy (b) The use of practically anhydrous re drate, an alkyl nitrite Such as ethyl nitrite action mediums and ingredients. and an alcoholate solution such as is pro 85 The reaction in modification (() may be duced by the action of caustic soda on anhy expressed by the following equation. drous ethyl alcohol. Furthermore, the so dium azide thus formed precipitates out in 3 5 NHHO--CHNO.--Na(OH the mother Solution in a high state of purity NaN.--C.H.OH--3i O. and may be removed by simple filtration. 90 In this case a large part of the Sodium Our linethod of producing Sodium azide azide stays in solution with other' ingredients is indicated by the following example run: such as excess materials and by-pi'oducts and One kilogram of hydrazine hydrate solu :0 the product is isolated by the addition of a tion containing 500 grams of NH is mineral acid and absorbing the thus liber mixed with 7.49 kilograms of a solution of 95 ated hydrazoic acid in a solution of sodium Sodium hydroxide in absolute ethyl alcohol hydroxide, according to the following equa (7.5%); to this mixture, which is contained tions: in a well-cooled receptacle, fitted with a re flux condenser, is added 1.76 kilograms of 1) 2N: N.--HSO-HN.--NaSO. ethyl nitrite. After a few minutes a vio 00 ( 2) HN.--NaOH-NaN-|-H.O. lent reaction sets in and pure white sodium In modification (b) the reaction may be azide is thrown out of solution. As the vio expressed as follows: lence of the reaction subsides the mixture is 50 allowed to come to room temperature and NH-CHNO.--CHON al after standing for two hours the sodium 05 NaN-2CHOH--H.O. azide is removed by the simple process of In this case practically anyhdious mate filtration. Upwards of 0.8 kilogram of so rials are employed such as absolute alcohol, dium azide having a purity of 90% or higher 1,628,380 is obtained. The product may be further hol, potassium hydroxide, and amyl nitrite purified by suitable Washing ol' by crystal may be employed to yield potassium azide. lization. Having described our invention we claim: in the above example run we have specified 1. The herein described process of manu 5 a concentration of alcoholate equivalent to facture of sodium azide which consists of 7.5% of sodium hydroxide in absolute alco bringing together hydrazine hydrate, an al hol. We have found that this concentration kyl nitrite and a sodium alcoholate solution 50 inay be varied from five to ten percent with 2. The herein described process of man ut greatly affecting the efficiency of the ufacture of sodium azide which consists of O pi'ocess. We have also specified sufficient bringing together hydrazine hydrate, ar. alcoholate solution to give approximately the alkyl nitrite and an alcoholate Solution pro theoretical l'equirements of sodium. The duced by the action of caustic soda on an oi'etical requirements of this ingredient are hydrous ethyl alcohol. sufficient for an efficient reaction but an ex 3. The herein described process of man 5 ce:S may be used. Also, since in cases where ufacture of sodium azide which consists of the sodium added as sodium hydroxide is de Subjecting an anhydrous alcohol to the action ficient, or in theoretical quantity it is found of caustic soda and mixing the resulting so 60 to be practically all combined as sodiuln lution with an aqueous solution of hydrazine azide after the reaction, it is obvious that and an excess of an alkyl nitrite 20 oili' invention is not impi'actical even when 4. The herein described process of manu there is a considerable deficiency of sodium. facture of sodiul azide which consists of Therefore, We, claim that the use of Only Subjecting an anhydlous alcohol to the action 65 75% of theory of sodium hydroxide is with of five to ten percent of caustic soda and mix in the scope of our invention. ing the resulting solution with an aqueous Furthermore we have specified a 50% so Solution of hydrazine of such strength as to lution of hydrazine. The concentration of yield at least one unit of hydrazine to three this solution, also, may be varied at will. units of water, and an excess of ethyl nitrite. 7) The concentration of hyd'azine should, how 5. A process fol' the manufacture of al ever, be sufficiently high to maintain a final kali-lanetal : Zides, which consists of bringing ratio of hydrazine to Watei', including the togethel', in a suitable reaction chanaber, a water formed in the reaction, of at least one solution of a sodium alcoholate formed by unit of hydrazine to three units of water. the bringing together of from 5 to 10% of 75 Hydrazine and hydrazine hydrate are equiv an alkali metal hydroxide, and an anhydrous alents in so far as this process is concerned. alcohol, and an aqueous solution of hydra 4. While we have specified a 50% excess of Zine containing sufficient, hydrazine to give ethyl nitrite we have found that this excess a ratio of at least one unit of hydrazine to may be varied at will. three units of water, including the water 80 In the above procedure we have specified formed in the reaction, and an excess of an the use of ethyl alcohol, sodium hydroxide, alkyl nitrite. 40 and ethyl nitrite. We have found, however, In testimony whereof they affix their sig that the reaction proceeds equally well with natures. other alcohols, other alkalies, and with other FRANK WILCOXON. alkyl nitrites. For instance, methyl alco BENNETT GROTTA.