2,980,505 United States Patent Office Patented Apr. 18, 1961 2 It follows that the known process of making cyanates does not at all suggest to a person skilled in this art the proc 2,980,505 ess according to the present invention which yields an PROCESS OF PRODUCING ALKALIMETAL entirely different compound. SALTS OF UREA When producing alkali metal salts of urea according to the present invention, care must be taken that moisture Karl Hass and Kurt Deselaers, Luelsdorf, uber Troisdorf, is excluded because the presence of moisture may cause Germany, assignors to Feldmuehle Papier- und Zells undesired side-reactions, as urea reacts with water and toffwerke A.G., Dusseldorf-Oberkassel, Germany the alkali metal alcoholate to form an alkali metal car No Drawing. Filed Nov. 12, 1958, Ser. No. 773,136 bonate and ammonia. . . O The alkali metal salts of urea obtained according to Claims priority, application Germany Nov. 16, 1957 the present invention can be used as such without further purification, for instance, in the preparation of urea com 9 Claims. (C. 23-75) pounds substituted by organic radicals or groups. Such urea compounds are known as ureides. Said reaction pro The present invention relates to the production of 5 ceeds in a very simple manner. For instance, compounds metal salts of urea and more particularly to the produc which contain reactive chlorine in organic linkage are con tion of alkali metal salts of urea. verted, on reaction with the alkali metal salts of urea ac Alkali metal salts of urea are known. For instance, a cording to the present invention, into urea compounds potassium salt of urea of the formula CO(NHK) has substituted by organic radicals or groups, whereby alkali been described in "Beilstein's Handbuch der Organischen 20 metal chloride is formed as by-product. Chemie,'' 4th Edition, vol. III, page 46. Such alkali metal A further example of utilizing the alkali metal salts salts of urea are useful as intermediates in the prepara containing mole of alkali metal for each mole of urea tion of other valuable chemical compounds. is their thermal decomposition. When heating the salt to It is one object of the present invention to provide a a temperature exceeding 100 C. and preferably to a simple and effective process of producing alkali metal 25 temperature between about 110° C. and about 150° C. salts of urea. the corresponding alkali metal cyanate of a high degree The process according to the present invention consists of purity is formed whereby ammonia is split off. The in principle in intimately mixing finely pulverized urea resulting alkali metal cyanate is substantially free of in solid form with a finely pulverized solid alkali metal cyanide. In contrast to the known process, whereby urea alcoholate and heating the mixture to an elevated tem 30 and alkali metal alcoholates are reacted at a temperature perature below 100° C. and preferably to a temperature exceeding 100 C. and whereby ammonia and alcohol between about 75 C. and about 95 C. This process are split off simultaneously, the new process of producing permits the production of alkali metal salts of urea in an such alkali metal cyanates according to the present inven especially simpler manner. When using as starting mate tion has the advantage that only ammonia is formed in rials sodium methylate and urea in equimolecular amounts, 35 the second reaction step and that, therefore, the hereto the reaction may be illustrated by the following equa fore necessary complicated process of separating am tion: - . monia and alcohol from each other in order to recycle said H.N.C.O.NH-i-NaOCH-NaHN.C.O.NH+HOCH compounds is avoided. Solid Solid Solid Vapor - The following examples serve to illustrate the present It is quite surprising that this reaction between solid 40 invention without, however, limiting the same thereto, organic compounds can be carried out with an almost Example 1 quantitative yield. It is furthermore of great advantage that the process according to the present invention yields 60 kg. of finely pulverized urea and 54 kg. of finely directly a technically useful product which is stable on pulverized sodium methylate are intimately mixed with storage and shipment, which does not need to be puri 45 each other in a vacuum-tight vessel provided with a fied and from which no impurities need be removed stirring device. Thereby moisture is carefully excluded. since the reaction is carried out in the absence of addi As soon as the urea and the sodium methylate powder tional substances. are completely and uniformly mixed with each other, It is another advantage of this process that the alco the mixture is heated to a temperature between about hol recovered as by-product can be recycled and reused 50 75 C. and about 95 C., while stirring is continued. for producing the required alkali metal alcoholate, for Methanol is split off and the mixture attains a dough instance, by reaction with the alkali metal amalgam of like consistency. The methanol is continuously distilled an electrolytic mercury cell. Preferably, the reaction is off in a vacuum of 90 mm. Hg and is condensed carried out in a vacuum-tight reaction vessel and in a in a condenser attached to the reaction vessel. It can vacuum. Vacuum accelerates the reaction and facilitates 55 be reused without further purification for producing so removal of the alcohol split off during the reaction from dium methylate in an electrolytic mercury cell. the reaction product. As stated hereinabove, any increase of the reaction As stated above, the reaction temperature must be temperature above 100° C. must be avoided, because kept below 100° C. in order to exclude side-reactions; otherwise the resulting sodium salt of urea is decom for, it is known that urea and alkali metal alcoholate are 60 posed into sodium cyanate and ammonia. The stirring converted into cyanates when exposed to higher tempera device in the reaction vessel is preferably constructed tures. Thereby not only the alcohol but also ammonia in such a manner that it causes pulverization of the are split off. Therefore, in order to avoid splitting off of resulting urea salt during cooling. In such a finely ammonia, the reaction temperature in the process accord pulverized form the sodium salt of urea can directly ing to the present invention must be kept at least below 65 be used for chemical reactions or can be packed for 100° C. shipment. Another difference of the process according to the Example 2 present invention over the known process of producing cyanates consists in carrying out the reaction in the ab 70 kg. of finely pulverized potassium methylate and sence of any organic liquid serving as solvent. In con 70 60 kg. of finely pulverized urea are intimately mixed trast thereto, cyanate formation according to the known with each other in the reaction vessel used in Example 1. process is effected in the presence of an organic solvent. Reaction sets in at a temperature of about 25 C. and - 2,980,505 3 4 no additional heat need be supplied as the heat of reac 2. The process according to claim 1, wherein the tion causes a considerable increase in the temperature intimate mixture of urea and alkali metal alcoholate of the mixture. Care must be taken that a temperature is heated to a temperature between about 75 C. and of 75 C. is not substantially exceeded in order to avoid about 95 C. potassium cyanate formation. If necessary, the reac 3. The process according to claim 1, wherein the reac tion mixture is cooled. tion is carried out with the exclusion of moisture. Example 3 4. The process according to claim 1, wherein the reaction is carried out in a vacuum and wherein the The sodium salt of urea obtained according to Exam alcohol split off is removed by vacuum distillation. ple 1 or, respectively, the potassium salt of urea obtained 0 5. In a process of producing the sodium salt of urea, according to Example 2, are heated in a reaction vessel the steps which comprise intimately mixing finely pull provided with a stirring device to a temperature be verized solid urea with a finely pulverized solid sodium tween about 110' C. and about 150 C. until no more methylate and heating the resulting mixture at a tem ammonia is split off. The resulting reaction product perature between about 75 C. and about 95 C. until no is a substantially pure and cyanide-free sodium cyanate 5 more methanol is split off. or, respectively, potassium cyanate. The ammonia split 6. In a process of producing the potassium salt of off during this reaction is substantially pure and can urea, the steps which comprise intimately mixing finely be used without further purification. pulverized solid urea with a finely pulverized solid potas Although the alkali metal methylates have proved to sium methylate and stirring the resulting mixture at a be especially suitable for the purpose of the present 20 temperature of about 25 C. without externally supply invention, because methanol is readily removed from ing heat thereto until no more methanol is split off. the reaction mixture due to its low boiling point, there 7. In a process of producing alkali metal cyanates, may also be employed the alkali metal alcoholates of the steps which comprise intimately mixing finely pull other alcohols, such as of ethanol, isopropanol, and the verized solid urea with a finely pulverized solid alkali like whereby, however, care must be taken that, on re 25 metal alcoholate, heating the resulting mixture at a moving the alcohols split off during the reaction, the temperature below 100° C. until no more alcohol is temperature is kept well below 100° C. split off, said temperature being higher than the boil As stated hereinabove, the reaction must be carried ing point of said alcohol in said mixture, separating out at a temperature below 100° C. When using sodium said alcohol from said mixture in the gaseous state, and methylate as the one reaction component, care should 30 increasing the temperature of the resulting alkali metal be taken that a temperature of about 95 C. is not ex salt of urea to a temperature substantially exceeding ceeded while, with potassium methylate, the tempera 100° C. until no more ammonia is split off.: ture is preferably kept below about 75° C. in order to 8. In a process according to claim 1, said alcoholate avoid formation of undesired by-products. - being an alcoholate of a saturated aliphatic alcohol hav. Of course, many changes and variations in the start 35 ing a carbon chain including not more than three car ing materials, the reaction conditions, duration, and boil atoms, and a boiling point at atmospheric pressure temperature, the apparatus used for carrying out the of not more than .85 C. reaction, the methods of removing the alcohol from 9. In a process according to claim 7, said alcoholate the reaction mixture and the like may be made by being an alcoholate of a saturated aliphatic alcohol hav those skilled in the art in accordance with the prin 40 ciples set forth herein and in the claims annexed hereto. ing a carbon chain including not more than three car We claim: bon atoms, and a boiling point at atmospheric pressure 1. In a process of producing alkali metal salts of of not more than 85 C. - urea, the steps which comprise intimately mixing finely References Cited in the file of this patent pulverized solid urea with the equimolecular amount of 45 a finely pulverized solid alkali metal alcoholate and UNITED STATES PATENTS heating the resulting mixture to a temperature below 1,816,911 Pfleger et al. ----is a Aug. 4, 1931 100 C. until no more alcohol is split off, said tempera 2,090,592 Jacobson ------Aug. 17, 1937 ture being higher than the boiling point of said alcohol 2,801,154 DePree et al. ------July 30, 1957 in said mixture. 50 2,889,198 Barrett et al. ------...- June 2, 1959