United States Patent Office

Patented June 13, 1950 2,511,653 UNITED STATES PATENT OFFICE 2,511,653 PREPARATION OF ALPHA-METHOXY PROPONTRLE Edwin William Shand, Pittsburgh, Pa., assignor to Sinclair Refining Company, New York, N.Y., a corporation of Maine. No Drawing. Application October 30, 1948, Serial No. 57,615 2 Claims. (CI. 260-465.6) 2 My invention relates to improvements in the F. desirable and prefer temperatures of about preparation of alpha methoxy nitriles such as 400-500 F. In addition, a more satisfactory alpha methoxypropionitrile, and, more particu conversion is effected when the slurry Of para larly, to a method of preparing alpha methoxy formaldehyde and nitrile is preheated to ten nitries by reacting an aliphatic nitrile and para s peratures in the range of 360°-510 F., depend formaldehyde, or nascent anhydrous formalde ing upon the particular reaction chamber ten hyde, in the presence of a dehydration catalyst perature employed. at elevated temperatures. Further details respecting my invention will When an organic cyanide is reacted with a be apparent from the following examples which compound such as formaldehyde, in the presence are set forth primarily for the purpose of illus of a dehydration-type catalyst, at elevated ten trating useful embodiments of my improved peratures, an unsaturated cyanide is formed. process. The examples illustrate once-through Such a process is disclosed in Brant et al. U. S. operation but obviously higher yields result from Patent No. 2,386,586, wherein formaldehyde as modification for repeated contacting. Formalin and propionitrile are reacted over a 5 Eacample I dehydration agent, such as alumina or silica gel at 350°-750° E. and an 80 to 88% yield of metha 21.5 gms. of paraformaldehyde were added to crylonitrile is recovered. 80.1 gms. of propionitrile to form a slurry in have now discovered, however, that anhy which the paraformaldehyde was kept in sus drous formaldehyde, when reacted with a nitrile 20 pension by a motor-driven stirrer. The solution such as propionitrile in the presence of a dif was preheated to 360°-375 F. and then fed over ficultly reducible oxide of a metal of group II, a period of one hour into a reactor vessel con III or IV of the periodic table, e. g., alumina, taining a catalyst bed of 50 cc. of alumina, So at elevated temperatures yields an alpha meth heated that the temperature of the bottom of Oxynitrile in contrast to expectations based upon 25 the alumina bed varied between 370-460° E. and the general experience of the art. For example, the temperature of the top between 375-390 F. over the reaction period. I have found that when paraformaldehyde is USed At the end of the one hour period the total as an in situ source of formaldehyde and dis feed was 90.5 gms, and 8.5 gms. of Solids and persed in liquid propionitrile and the slurry is 41.5 gms. of liquid, principally alpha methoxy reacted over alumina as catalyst at a temperas 30 ture within the range approximating 350-685 propionitrile, were recovered. The liquid also F., preferably about 400-500 F., alpha, methoxy contained. Some traces of unreacted paraformal propionitrile is produced in good yields. dehyde and propionitrile, but no methacrylonit irie Was found. The anhydrous formaldehyde thus is generated The boiling point of the liquid recovered was in the reactor vessel when the slurry of para 35 formaldehyde and propionitrile is heated in the 86°-123° C., with 80% boiling at 119°-122° C. presence of the alumina catalyst. The nascent The refractive index at 20° C. was 1.3935, and gas then reacts in situ with the propionitrile the density (20/4) was 0.8973. The percentage to form alpha, methoxy propionitrile. nitrogen found was 16.7. I have found, in Unexpected contrast, that if 40 Eacample II the process is conducted by charging the formal This run Was performed in the Same manner dehyde as a gas in the monomeric state, e. g., as Example I, except that all of a dispersion of by preheating the paraformaldehyde to, Say, 45.0 gms. of paraformaldehyde in 96.5 gms. Of 220-575° F., and passing the gas so formed propionitrile, preheated to 490°-510 F., was fed through a heated tube to the reactor vessel, the 43 into the reactor vessel containing an alumina reaction does not go. It appears therefore that catalyst bed of 50 cc. over a period of 134 hours. the formaldehyde must be generated in contact The top temperature of the bed Was varied be with the catalyst and propionitrile. tween 50-695 E., and the bottom between 490° The temperature of the reaction should be 685 F. The tendency of ungasified paraformal sufficient to generate anhydrous formaldehyde 50 dehyde to plug the reaction system was reduced in considerable quantity from the paraformalde at these temperatures. hyde. Thus a minimum temperature of about At the end of 134 hours, 11.0 gms. of the Solids 212 F. to a maximum of about 800° F. is indi and 30.2 gms. Of the alpha methoxy propionitrile cated, although in actual practice I have found liquid were recovered. In addition, 8.0 gms. of elevated temperatures of the order of 350°-685 water Were produced in the conversion, indicat 2,511,658 3 4. ing the occurrence of some dehydration. No IV of the periodic table such as thoria, zirconia, methacrylonitrile was found in the liquid prod beryllia, are useful. I have found, however, that uct, but the solid residue remaining in the re the reaction does not appear to proceed with actor contained a polymeric material soluble in the well known non-metallic dehydration cata alcohol. Accordingly, it appears that under the lyst, silica gel. Variations in the reaction condi conditions of this run a minor amount of de tions and manipulative procedure are permissible hydration and polymerization of the unsaturated as indicated to the art by the nature of the product occurred. I conclude that the more starting nitrile, the catalyst, or the presence of moderate conditions of temperature favor the Solvent. production of alpha methoxy propionitrile al O Alpha, methoxy propionitrile is valuable as a though higher temperatures promote ease of fungicide, insecticide, and the alpha methoxy Imanipulation by maintaining the reactants and nitriles generally have utility as solvents and products in fluid form. intermediates in organic synthesis. My invention The liquid recovered boiled over the range, thus provides a new reaction mechanism under 67°-122° C., with 57% boiling between 119°-122° C. 15 dehydration conditions, and provides for the The material boiling between 118-122° C. for production of alpha methoxy nitriles by an im both runs was composited and the methyl ester proved and unexpected means. was prepared. A comparison of its physical I claim: characteristics with those found in the literature 1. In the preparation of alpha, methoxy pro are tabulated below: 20 pionitrile the improvement which consists of re acting a slurry of paraformaldehyde and pro Refractive pionitrile in the presence of alumina at a Methyl Ester PE". Inde,at 20 temperature in the range approximating 350° to 685° E. Found--------------------------- 129.2-129,8 1397 25 2. The process which comprises reacting nascent Literature Data--------------------- 29.5-129.8 3968 anhydrous formaldehyde with propionitrile in the presence of alumina at a temperature in the The reaction illustrated in the examples is ap range approximating 350 to 685 F., and recover plicable to other aliphatic nitriles including ing alpha, methoxy propionitrile from the re alicyclic nitriles and polynitriles Such as Succino 30 action products. nitrile. For example, approximately equimolar EDWIN WILLIAM SHAND. proportions of say acetonitrile, butyronitrile or cyclohexane carbonitrile and paraformaldehyde REFERENCES CTE) are reacted to produce the corresponding alpha The following references are of record in the methoxy derivatives. In the case of solid nitriles, file of this patent: an appropriate inert solvent, e. g. hexane, is ad vantageously employed in the preparation of the UNITED STATES PATENTS reaction mixture. Further, for the alumina, Number Nane Date catalyst of the examples, other difficultly re 2,285,948 Rust --------------- June 9, 1942 ducible oxides of metals of groups II, III, and k 2,386,586 Brant et al. --------- Oct. 9, 1945 .

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