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Patented Jan. 6, 1931 1,787,483 UNITED STATES PATENT OFFICE BURRITT SAMUEL LACY, OF RED BANK, NEWJERSEY, AssIGNOR, BY MEsNE AssIGN MENTS, TO THE ROESSLER & BASSLACHER CEEMICAL COMPANY, OF NEW YORK, N. Y., A. CORPORATION OF DELAWARE PROCESS OR BE PRODUCTION OF FOR AMIDE NoDrawing. Application filed November 17, 1925. Serial No. 89,708. This invention relates to the formation of the reverse not only of this reaction but also formamide from ammonia and carbon mon of the analogous reaction with the methyl oxide. While this reaction is not unknown, compound is catalyzed by sodium ethylate the literature is full of records of unsuccess resp. sodium methylate, thus:- 50 5 highful attempts pressures and and work expensive involving equipment. the use Asof C. CO+CHOH=HCOOCH. an example of these unsuccessful attempts However, in carrying out reaction C and that of Meyer & Orthner, Ber. 54B 1705 the analogous reaction between ethyl alco (1921) at 125 atmospheres with clay as a cat hol and carbon monoxide, not only did Staeh 10 alyst is most conclusive. The result has been ler use enormous pressures, but the time con a complete lack of commercial development. sumed by the operation made it very imprac Aside from the attempts to make form tical for commercial use. Thus Staehler used amide by the direct reaction between carbon a pressure of 300 atmospheres in reacting monoxide and ammonia, there have been de with ethyl alcohol to form ethyl formate, 15 scribed in the literature reactions by which and one of 160 atmospheres in reacting with 60 it might be considered possible to obtain methyl alcohol to form methyl formate; formamide indirectly from carbon monox while there was required a reaction period of ide and ammonia as the ultimate raw ma 14 days at room temperature to produce a terials, but the conditions under which these 45% of theory conversion of ethyl alcohol to 20 reactions occurred were such as to discour ethyl formate, and one of 8 days (partly at 65 age employing them for the commercial pro 100-120° C. and partly at room tempera duction of formamide. In particular, it has ture) to produce an 84% of theory conversion long been known that formamide can be of methyl alcohol to methyl formate. In made by the reaction between ethyl formate order to obtain formamide as the end prod uct it would, of course, then have been neces 70 25 and ammonia, as follows:- sary in addition to carry out the separate A. NH,+HCOOCH= operation represented by reaction A or B. HCONH+CHOH I have now discovered a simple and con (Hofmann, Jn. Chem. Soc. vol. 16, year venient method of producing formamide 30 1863, page 73.) So far as we are aware, the directly from carbon monoxide and ammonia. 75 analogous reaction with methyl formate i. e. In my method I react carbon monoxide and ammonia in an alcohol, preferably methyl B. NH--HCOOCH=HCONH--CHOH alcohol, as a solvent, using as a catalyst a has not been described; and while one would metallic alcoholate, preferably sodium 35 reasonably expect it to occur, the extent and methylate, at a relatively low pressure, such 80 as for instance 4 atmospheres. As an ex speed of the reaction could not be known be ample of a convenient pressure at which to forehand. Furthermore, it has been known operate I prefer about 17 atmospheres. I have since 1868 (Geuther, Zeitschrift für Chemie, found that the speed of the reaction increases . 1868, page 655; Chem. Centralblatt, 1868, with the pressure, so that, while the reaction 85 40 page 632) that sodium ethylate is a catalyst will take place at lower pressures I give for the reaction an example of use at about 17 atmospheres. HCOOCH=CO+CHOH, This pressure was chosen on a comparison and since 1914 (Staehler, Berichte, vol. 47, basis of cost of apparatus for pressure work 45 1914, page 589) that, as might be anticipated, as against cost of operation due to the time 1,787,488 of reaction. Ordinary fittings such as used autoclave; finally the formamide itself was for liquid ammonia processes are easily distilled off, preferably at reduced pressure. adaptable for use in my process at 17 atmos The amount of unreacted ammonia recovered pheres thus allowing a relatively high pres was S7 grams or 5.1 moles, so that 69.1-5.1 = sure at a low installation cost. I have oper 6-4.0 moles ammonia had disappeared; while ated successfully in an autoclave of ordinary the amount of pure formamide obtained by O steel, but autoclaves comprised of, or lined distillation was 2717 grams or 60.4 moles; with other materials, for exampletin, which consequently the formamide yield was are specially resistant to the action of the materials employed may be advantageously 100+S-94.4% 75 used. The reaction will go on more rapidly 640 at higher pressures such as 30 to 40 atmos of theory referred to the ammonia which pheres but installation costs, will of course disappeared. The overall loss of 5.6% of tend to be higher. Depending on the pres theory includes losses in distillation, trans 5 sure employed, the optimum reaction tem fer, etc. as well as any possible side reac 80 perature is likewise variable, running from tions. 50° C. and up, preferably not over 100° C., At one time during this run the reaction although higher temperatures may be used. pressure was allowed to drop to 120 pounds I have found that a suitable temperature to per square inch. It was found that during 20 use with 17 atmospheres pressure is about this low pressure period that the reaction con 85 70° C. Using this temperature and pressure tinued, as shown by gas absorption, but that I obtain formamide yields of 95% of theory the speed of reaction was less. based on the ammonia reacting. The fact I do not desire to limit myself to the exact that this remarkable yield was obtained, and conditions herein set forth since many varia 2 5 moreover underconditions easily and econom tions are possible within the scope of my in 90 ically attainable on a commercial scale is vention. While there may be no technical . wholly unexpected in view of all previous at advantage in pressures differing widely from tempts to combine carbon monoxide and am those I have indicated, our measurements of monia to form formamide, as these had given the equilibrium of this process show that re 30 results which were unsatisfactory in regard action occurs to a considerable extent at any 95 to yield and type of apparatus required. pressure over atmospheric. Similarly, wide To illustrate my process the following ex temperature variations are permissible. The ample is given: molecular ammonia-carbon monoxide ratio I 2388 grams methyl alcohol was placed in have indicated at 1:1, this however is not an 35 an autoclave containing about 117 grams absolute necessity. In fact we have found OC sodium methylate, the autoclave being pro that a higher reaction velocity, and conse vided with an efficient type of agitator so as quently a greater production capacity for an to keep the liquid phase at all times nearly autoclave of a given size, is obtainable by saturated with the gas and vapor present keeping the ammonia in considerable excess 40 above the liquid phase. The temperature of over the carbon monoxide during all but the the alcohol was now raised to about 70° C. last part of the process, when the balance of and then ammonia and carbon monoxide were the carbon monoxide is run in. Thus in a run admitted rapidly till the pressure in the auto similar to that just given, differing however clave reached approximately 245 pounds per in that about 34 of the total ammonia was 45 square inch absolute pressure, or about 16.7 run in before starting to pass in carbon mon 10 atmospheres; the ammonia and carbon mon oxide, the time of the whole reaction was oxide addition was now regulated so as to shortened from 834 hours to 3 hours. maintain this pressure. The ammonia and Instead of methyl alcohol and sodium carbon monoxide were run in simultaneously methylate as the reaction medium, ethyl alco 50 in equimolecular proportions, this being regu hol and sodium ethylate may be used. The lated by observing the pressures of both be results are approximately the same, so that fore mixing, i. e. the ammonia pressure was the reaction appears to be a general one with 125-130 pounds per square inch and the car a medium consisting of alcohol and metal bon monoxide the same. The introduction alcoholate, especially with the simpler mono 5 5 of the gases was continued for 834 hours. hydric alcohols. In the case of ethyl alcohol, It became necessary then to end the run be the chief practical difference is that the ethyl cause of the limited capacity of the auto alcohol left at the close of this reaction, since clave. A total of 1175 grams (69.1 moles) it is less volatile than the methyl alcohol, re ammonia and 1975 grams (70.5 moles) of quires a correspondingly higher temperature 60 carbon monoxide had been passed into the to distill it off. Furthermore it is much less autoclave. The contents of the autoclave easy to remove from the ethyl alcohol water were now weighed, and found to amount to which may tend gradually to accumulate in 5465 grams. The alcohol and the unreacted the system; such water should be kept at a ammonia were then distilled off, and were low figure in order to prevent unfavorable 65 available to be used in again charging the action on the alcoholate.