Patented June 15, 1948 2,443,420

UNITED STATES PATENT OFFICE 2,443,420 SYNTHESIS OF William F. Gresham, _Wilmington, DeL, assignor to E. I. du Pont de Nemours & Company, Wil mington, Del., a corporation of Delaware No Drawing. Application February 21, 1946, Serial No. 649,381 9 ‘Claims. (Cl.- 2605-4651) 2 . This invention relates to the synthesis of ni mixture of the aldehyde and over triles, and more particularly to the synthesis of grains of the catalyst at the aforesaid temper nitriles from aldehydes and ammonia in the pres atures and pressures, and thereafter separating ence of speci?c catalysts. The process of the in the from the resultant reaction product. vention may be illustrated in a specific embodi One convenient method for separating the said ment by means of the following equation: nitrile is to cool the reaction products by means ' of a -cooled condenser and to distill the Co or Cu=Zn resulting condensate. catalyst ' . omcmono + NH; —-» onlcmcn + mo '+‘H, In certain instances the reaction product ob '10 tained in accordance with the invention con It has vbeen known heretofore that certain tains in addition to the nitriles certain pyridine aliphatic and aromatic nitriles can be prepared derivatives, the formation of which'may be sup by reaction between ammonia and aldehydes at pressed through the use of specific catalysts, such elevated temperatures in the presence of catalysts as metallic cobalt or catalysts containing copper such as thorium oxide. These prior art processes, 15 and zinc in combination. By way of contrast, in however, invariably gave low yields of the desired the reaction between and am nitriles, and accordingly they have not been com monia in the presence of alumina catalysts in the mercially successful, even‘ though the reactants absence of these metals, virtually no propionitrile are relatively inexpensive and the nitriles them is produced, and appreciable quantities of 2-ethyl selves are highly valuable as chemical interme 20 3,5-dimethyl pyridine are generally obtained; diates. similarly, in the preparation of from An object of this invention is to provide a proc and ammonia, appreciable quanti ess whereby nitriles can be obtained from alde ties of alpha-picoline are thus frequently ob hydes and ammonia in high yields. A more spe-. tained. One of the advantages of using the pre ciflc object of the invention is to provide an im 25 ferred catalysts is that the formation of these proved and commercially feasible process for the by-products can be prevented or suppressed manufacture of propionitrile. Other objects of thereby. I the invention will appear hereinafter, The catalysts employed in the practice of the These objects are accomplishedgin‘ accordance invention are preferably prepared by at least with the invention by reacting an aldehyde of the partially reducing the metal oxides with hydro formula R(CHO)n (R being a hydrocarbon radi gen or a donor such as , care cal containing from 1 to 8 carbon atoms, pref being taken to avoid excessive overheating dur erablyf 2 to 8 carbon atoms; n being 'an integer ing the said reduction. Themethod of reducing from 1 to 2 inclusive) with ammonia in the pres the catalyst is, in fact, highly critical; 1. e., for ence of a metallic catalyst containing as an optimum results, it. is necessary to exercise care essential constituent a member of the class con 85 sisting of cobalt and copper, preferably as more ful control over the heat evolved and other vari Although ables. For example, with Cu-Zn catalysts, this ‘speci?cally hereinafter illustrated. can be accomplished conveniently by reducing the combinations of copper, manganese and‘of cop per and magnesium gave good results in carry catalyst with aqueous methanol at a tempera ing out the invention, preferably the synthesis 40 ture of 330° to 350° C. of nitriles is accomplished in accordance with the The term "metallic” as employed herein signi invention in the ‘presence of a speci?c type of lies not only the metals themselves, but metals metallic catalyst, namely a catalyst containing in the form of their oxides or in other similar, metalliferous, reducible forms. Expressions such both copper and zinc. 45 The process of the invention may be carried as Cu-Zn mean catalysts in which the several out at temperatures of about 275° to 500° 0., pref-' named ingredients (in this instance copper and erably about 300° to 350° C. The pressure may zinc) are present in "metallic” form. Cu-Zn or ' be varied rather widely, but‘ atmospheric pres C0 catalysts, may, of course, containin addition sure is generally preferred. ' Subatmospheric to the ‘named metallic ingredients, various rela pressures may also be employed'but they are 50 tively inert materials, but such materials are gen generally not necessary. . ; erally neither necessary nor desirable. The invention may be practiced by passing a The mol ratio of ammoniai aldehyde initially 2,443,420 3 4 introduced into the reaction vessel in accordance was the conversion as high as had been obtained with the invention may vary widely, but is gen as disclosed in Example 1 with a Cu-Zn catalyst. erally within the range of about 1:1 to 10:1. If In most of these tests one of the chief by-prod desired'the reaction mixture may also contain , ucts was 2-ethyl-3,5-dimethyl pyridine. - water ‘or inert gases such as , and the ' It is to be understood that the above examples like, but, with the preferred catalysts high yields are illustrative only and that they do not neces are obtainable without using inert diluents. sarily limit the invention. Numerous modi?ca The aldehydes which may be employed in the tions of the invention will occur to those skilled practice of the invention include the lower ali in the art. For example, catalysts in a ?nely di phatic aldehydes, such as acetaldehyde, propion 10 vided particulate state, suitable for use in "fluid aldehyde, isobutyraldehyde, adipic dialdehyde, catalyst" techniques. may be employed if desired. etc.; unsaturated aldehydes, such as and ‘Any convenient method may be used for sepa methacrylaldehyde; and aromatic and naph rating the nitrile from the reaction‘ products. thenic aldehydes such as benzaldehydc, toluic The nitrlles obtained in accordance with the aldehyde, cyclohexylacetaldehyde, and the like. 15 present invention are widely useful per se, and The invention is especially ‘valuable when em are especially valuable for example, in the manu ployed in the manufacture of propionitrilc from facture of acrylonltrile and methacrylonitrile, 'propionaldehyde and ammonia, or isobutyroni which are obtainable in high yield by passing the trile from isobutyraldehyde and ammonia. appropriate saturated nitriles (propionitrile and The invention may be illustrated further by 20 isobutyronitrile) over conventional dehydrogena means of the following examples. It is to be un tion catalysts at elevated temperatures. derstood that the method of Example 1 is equally Since many different embodiments of the in applicable in preparing other nitriles, particularly vention may be made without departing from the isobutyronitrile and . spirit and scope thereof, it is to be understood Example 1.—A copper-zinc catalyst of the for 25 that I do not limit myself except as set forth in mula 1Cu : 2Zn was prepared by reducing the ig the following claims. nited coprecipitated oxalates (carbonates give I claim: similar results) at 330° to 350° C., with 2% aque 1. A process for preparing nitriles of the for ous methanol until the analysis of the oil’ gas in mula R(CN)n, R being a hydrocarbon radical dicted that the only reactions occurring were the 80 having from 1 to 8 carbon atoms, 12 being an ‘pyrolysis of methanol and the reaction integer from 1 to 2 inclusive, which comprises re~ acting ammonia with an aldehyde of the formula R(CHO)n in the presence of a metallic catalyst A mixture of propionaldehyde (space .velocity, containing both copper and zinc at a tempera- - 197) and ammonia (space velocity, 800) was 35 ture of about 275° to 500° C. and thereafter sepa passed over the reduced catalyst ate tempera rating from the resultant reaction product the ture of 300° to 330° C. After leaving the catalyst: nitrile of the formula R(CN)n produced by the the gases passed through a water-cooled conden said reaction. ser, and the resulting liquid condensate, which 2. A process for preparing nitriles of the for was a mixture of water. nitrile. ammonia, and mula R(CN)n. R being a hydrocarbon radical small quantities of by-product amine. was dried. having from 1 to 8 carbon atoms, n being an in This was accomplished by extracting with chloro teger from 1 to 2 inclusive, which comprises re form and adding potassium carbonate to the acting ammonia with an aldehyde of the for chloroform layer. The resulting chloroform so mula R(CHO)n in the presence of a metallic cat lution of non-aqueous reaction products was fil 45 alyst containing both copper and zinc at a tem tered and distilled, yielding a fraction boiling perature of about 300° to 350° C. and thereafter at 95° to 97° C., which was relatively pure pro separating from the resultant reaction product pionitrile. Another propionitrlle out. which had a the nitrile of the formula R(CN)n produced by boiling point of 59° at 200 mun, was also obtained. the said reaction. , _ The conversion of propionalclehyde to propioni 50 3. A process for preparing nitriles of the for trile was 77% of the theoretical, taking into ac— mula RCN, B. being a hydrocarbon radical having count further quantities of propionitrile iso from 2 to 8 carbon atoms, which comprises re lated by redrying and redistillinz the foreshot acting ammonia with an aldehyde of the formula cuts obtained in the initial distillation. RCHO in the presence of a metallic catalyst con Example ‘Zr-Example 1 was repeated under 55 taining both copper and zinc at a. temperature substantially similar conditions. using, in place of about 275° to 500° C. and thereafter separat of the Cu: Zn catalyst, the catalysts listed, in the ing from the resultant reaction product the ni following table. trile of the formula RCN produced by the said re ‘Conversion of propionaldehude and ammonia action. to propionitrile 60 4. The process of claim 3 in which the said al dehyde is propionaldehyde and the said nitrile is propionitrile. Conversion I Run No. Catalyst to Pro ioni 5'. The process of claim 3 in which the said al tri a dehyde is isobutyraldehyde and the said nitrile ‘as is isobutyronitrile‘. Per cent 1 ...... - Cu-Zn-Cr-K ...... __ 44 6. The process of claim 3 in which the said al ' Cu-Zn-Cr ...... 41 dehyde is benzaldehyde and the said nitrile is s _ Cu-Or-Zn'SiOI ------. 31. Co_ 46, benzonitrile. (Jo-Cr l3. '7. The process of claim 3 in which the said Cu-Mn-K...... 30 70 Cu- 5 33 catalyst is a Cu-Zn catalyst, which has been re ii ...... - Gu-Ag-AhOs ...... - 4. J ...... _ Cu-Cr-Mg ...... 7. duced by means of aqueous methanol at a tem perature of about 330° to 350° C. ‘ In each of the above tests a substantial quantity 8. The process of claim 3 in which the said of propionitrile was obtained. but in no instance 75 catalyst is a Cu-Zn-Cr-K catalyst. 2,448,}190 ‘ 5 6 9. The process or claim 3 in which the said catalyst is a Cu-Zn-Cr catalyst. FOREIGN PA IE." Is 7 , , Number Country ‘ Date WILLIAM I". GREBHAM. ‘ 332,258 Great Britain ___..___ July 18, 1930 ‘ 5 334,193 Great Britain _____ .._ Aug, 25, 1930 REFERENCES CITED 369,371 Germany ______Feb. 17,_ 1923 - 427,858 Germany _.._; ______Apr. 20, 1926 The following references are, of record in the 547,513 Germany ______Man 23, 1932 ?le of this patent: - 558,565 Germany ______-__ Sept. 8, 1932 UNITED sums PATENTS 1° OTHER REFERENCES Number Nam. m“ Malhle et al.: Comptes rendus (Fr. Acad.~ Sci), 1,936,995. Schlebht at al. _-__._ NOV. 28, 1933 DP. 215—21'7-(1918).v