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United States Patent (19) (11 Patent Number: 4,918,222 Lin Et Al

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United States Patent (19) (11 Patent Number: 4,918,222 Lin Et Al United States Patent (19) (11 Patent Number: 4,918,222 Lin et al. 45 Date of Patent: Apr. 17, 1990 (54) PROCESS FOR SYNTHESIS OF (56) References Cited N-ACETYLGLYCINE U.S. PATENT DOCUMENTS (75) Inventors: Jiang-Jen Lin, Round Rock; John F. 3,213,155 10/1965 Schriesheim et al. .............. 562/544 Knifton; Ernest L. Yeakey, both of . 3,766,266 10/1973 Wakamatsu et al. ............... 562/518 Austin, all of Tex. FOREIGN PATENT DOCUMENTS 73 Assignee: Texaco Inc., White Plains, N.Y. 1326014 8/1973 United Kingdom ................ 562/519 Primary Examiner-Vivian Garner 21 Appl. No.: 83,397 Attorney, Agent, or Firm-Jack H. Park; Kenneth R. 22) Filed: Aug. 10, 1987 Priem; Cynthia L. Kendrick (57) ABSTRACT Related U.S. Application Data An N-acetylglycine is manufactured by reacting para (63) Continuation-in-part of Ser. No. 635,077, Jul. 27, 1984, formaldehyde with an acetamide and carbon monoxide abandoned. in the present of a cobalt-containing catalyst promoted by a sulfoxide or dinitride compounds. The presence of (51) Int. Cl. .................. C07C102/00; C07C 103/50; sulfoxide or dinitrile ligands are essential for the high CO7C 103/48 yield synthesis of N-acetylglycine and good cobalt re 52) U.S. C. .................................... 562/518; 564/132; covery. 564/159 (58) Field of Search ................................ 562/518, 575 1 Claim, No Drawings 4,918,222 1. 2 N-acetylglycine was not encountered by other amidoa PROCESS FOR SYNTHESIS OF cid analogs. N-ACETYLGLYCNE N-acetylglycine (the smallest molecule in the amido acid family) has a melting point of 207 C. to about 209 CROSS-REFERENCE C., which makes the distillation techniques for isolating the product impractical. This highly polar product has This application is a continuation-in-part of U.S. pa also strong tendency to chelate cobalt metal. Compara tent application Ser. No. 06/635,077 filed July 27, 1984, tive Example 2 in this specification indicated >90% which will be abandoned. cobalt was deposited on the N-acetylglycine product. FIELD OF THE INVENTION 10 Therefore an improved catalyst system allowing for This invention relates to the improved catalyst sys high-yield and exhibiting good cobalt recovery would tem for amidocarbonylation of paraformaldehyde in the be desirable in order to achieve commercial feasibility. presence of acetamide in order to obtain N-acetylgly Many ligands or promoters have been used to im C18. prove the performance of cobalt catalysts. 15 In U. S. Pat. Nos. 4,209,467 and 3,996,164, amine More particularly this invention is an improved pro ligands including pyridine, 2-hydroxypyridine and cy cess for the production of N-acetylglycine, a possible cloaliphatic amines were employed with dicobalt oc intermediate for phenylalanine (a aspartame precursor) tacarbonyl for hydroformylation or carbonylation of or for glycine production, wherein paraformaldehyde is olefins. The function of the ligands was to stabilize the reacted with acetamide, carbon monoxide and hydro 20 catalyst and increase the product selectivity. gen in the presence of a cobalt-containing compound in In. U.S. Pat. No. 3,931,332, the importance of the a complex at a defined ratio of certain nitrile or sulfox cobalt and diamine promoter ratio was demonstrated. ide promoters and a solvent, at a temperature of about Increasing the added amount of added diamine-stabil 50 to about 150° C. and a pressure of 1000 to about izer markedly reduced the reaction rate of hydroformy 4000 psi, for a period of from 1 to 10 hours. The im 25 lation. A smaller amount of ligand to cobalt is preferred provement of this catalyst combination resides in the with respect to reaction rate. fact that the active cobalt catalyst can be maintained in In U.S. Pat. No. 4,612,403, an organic nitrile pro the solvent medium, the cobalt can be released from the moter was used to improve the process of hydroformy solid form of N-acetylglycine-metal complex and ulti lation. In U.S. Pat. No. 4,476,326, a sulfoxide promoter mately a significantly higher yield of N-acetylglycine 30 was used to improve the cobalt catalyst for methanol can be obtained than when using the cobalt catalyst homologation to ethanol by reactions with a CO-H2 alone. mixture. BACKGROUND OF THE INVENTION These products are aldehydes, alcohols, esters or carboxylic acids, which are distillable and less polar N-acetylglycine is an important chemical building 35 than N-acetylglycine. The use of these specific promo block for many chemical products, such as glycine, tors would not be relevant to N-acetylglycine synthesis. aspartame and other amino acids. More specifically, The amidocarbonylation of an aldehyde, amide and N-acetylglycine can be the intermediate for phenylala carbon monoxide to form an amidoacid involves the nine synthesis via reactions with benzaldehyde, fol cobalt catalyzed carbonylation of an aldehyde-aceta lowed by hydrolysis and selective hydrogenation of an mide adduct under unusually mild reaction tempera acetaminocinnamic acid intermediate (Chemical Mar tures (ca 120° C) compared with cobalt-catalyzed hy keting Reporter, May 14, 1984). droformylation carbonylation or methanol homologa The synthesis of N-acetyl-a-amino acid from alde tion. The examples in the instant invention demonstrate hyde and carbon monoxide was first reported by Waka the importance of certain ligands for this reaction. The matsu, in Chemical Communication, 1540, (1970) and 45 nature of the solid product which acts as a strong che U.S. Pat. No. 3,766,266. This patent teaches the use of lating agent required experimentation to find the most paraformaldehyde, acetaldehyde, propionaldehyde, suitable ligands. i-butyraldehyde, phenylacetaldehyde, 6-cyanopro For comparison, succinonitrile and sulfoxide ligands pionaldehyde etc. as reactants. The amide included in a aided the cobalt recovery and the product selectivity; formyl group and a carbamoyl group having at least one 50 diamine and acetonitrile (large amount used as solvent) active hydrogen atom. Where paraformaldehyde was adversely affected the reaction. Although these effects reacted with acetamide, N-acetylglycine was produced are not well understood, we believe that the suitability at only about 46% yield. Here there is the problem of of ligands is dependent on the strength of the ligand to the cobalt catalyst complexing with solid N-acetylgly cobalt complex and on the amount of ligands used. In cine product and causing the loss of cobalt from react 55 the process of the instant invention ligands have been ing solvent medium. This disadvantage has prevented relied upon which complexed with cobalt stronger than this synthesis from being commercialized. An improve the amido acid product did and which had no deactivat ment of this catalyst system would be desirable. ing ability. In amidocarbonylation, the aldehyde can be gener Our experimental results reveal that promoters which ated in situ from allyl alcohol, alkyl halide, oxiranes, work for oxo, carbonylation or other CO reactions alcohols and olefins followed by the reaction with could not be simply applied to amidocarbonylation. For amide and carbon monoxide to produce N-acyl- a example, amine ligands are not suitable for N-acetylgly amino acid. Disclosures of such reactions can be found cine synthesis. Furthermore, our invention particularly in Tetrahedron Letters, Vol. 23, No. 24, pp. 2491-2494, deals with paraformaldehyde to N-acetylglycine syn 1982; U.S. Pat. No, 3,996,288; German Offen. DE 65 thesis. Comparative example (3) illustrates that the syn 3,242,374 and U.S. Pat. No. 4,264,515, respectively. In thesis of N-acetylalanine from acetaldehyde, acetamide these references the synthesis of N-acetylglycine was and carbon monoxide did not have the problem of co not addressed. The problem of catalyst deposition on balt deposition because it exhibits less polarity. 4,918,222 3 4. ferred cobalt-containing compound is dicobalt Octacar SUMMARY OF THE INVENTION bonyl. The instant invention is related to an improved pro The promoter to be used in this catalyst System may cess for the synthesis of N-acetylglycine from paraform contain one or more sulfoxide groups per molecule. aldehyde, acetamide and carbon monoxide using an The general structure of sulfoxide promoter can be improved catalyst system. More particularly, this inven described as follows: tion relates to the use of a cobalt catalyst in complex with sulfoxide or certain defined dinitrile promoters. The improvements which have been demonstrated in clude: (a) good cobalt recovery in ligand solution and 10 (b) high yield or selectivity for N-acetylglycine The R1 and R2 group can be alkyls, such as methyl, DETAILED DESCRIPTION OF THE ethyl, n-butyl or n-hexyl, aromatic groups such as INVENTION phenyl, chlorophenyl, aminophenyl or tolyl, arylalkyls In the narrower and more preferred practice of this 15 such as benzyl or chlorobenzyl. The different R1 and invention N-acylglycines are prepared from a mixture R2 groups can also exist in the same sulfoxide molecule. of paraformaldehyde, an amide, carbon monoxide and Suitable examples include methyl sulfoxide, ethyl sulf hydrogen by a process which comprises contacting said oxide, n-butyl sulfoxide, methyl n-butyl sulfoxide, di mixture with a catalyst system comprising a cobalt-con phenyl sulfoxide, benzyl sulfoxide, methyl phenyl sulf taining compound promoted by a ligand containing (a) 20 oxide, 4-chlorophenyl sulfoxide, p-tolyl sulfoxide, and sulfoxide compounds or (b) dinitrile group, which is etc. The cyclic sulfoxide can also be used; such as tetra dissolved in a substantially inert solvent at a tempera methylene sulfoxide. ture of at least 50° C. and a pressure of at least 500 psi Another group of effective promoters used in this until substantial formation of the desired N-acetylgly invention to improve the cobalt catalyst comprises dini cine has been achieved. 25 trile compounds. The improved catalyst systems can be represented by The dinitrile may be added in the form of structure A.
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