Organic compounds -- part of the class 532-570 series – Organic compounds – Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
2000-04-05
2001-12-18
Kumar, Shailendra (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Unsubstituted hydrocarbyl chain between the ring and the -c-...
C564S197000, C564S198000, C540S539000
Reexamination Certificate
active
06331624
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for the preparation of 6-aminocaproamide. The 6-aminocaproamide is useful to produce caprolactam, which in turn is useful to produce nylon 6.
2. Description of Related Art
6-Aminocaproamide is a useful intermediate that is suitable for the manufacturing of caprolactam. U.S. Pat. No. 4,119,665 discloses a process for the manufacturing of 6-aminocaproamide by the reaction of ethyl-5-cyanovalerate with ammonia to produce 5-cyanovaleramide, which is then hydrogenated in the presence of ammonia and a supported cobalt and/or nickel catalyst to produce the 6-aminocaproamide. While the process of U.S. Pat. No. 4,199,665 provides good yields of 6-aminocaproamide, it can be hindered by the generation of one mole of ethanol per mole of product. Ethanol handling increases the process costs for waste treatment or recycling. Also, the patent limits the process for the manufacturing of 6-aminocaproamide to the use of a supported cobalt and/or nickel catalyst obtained by a specific process. The catalyst is made by calcining together an appropriate cobalt and/or nickel salt and an Al
2
(OH)
16
CO
3
support, thereby forming a solid catalyst which has cobalt and/or nickel distributed throughout it, not just on the surface of the support.
A process for the hydrogenation of cyanocarboxylic acid amides to produce the corresponding aminocarboxylic acid amides in the presence of an unpromoted Raney® nickel catalyst is described in Chemische Berichte 92,2619 (1959). The reaction of the publication occurs in a dioxane solvent and in the presence of ammonia. A process, which provides a higher rate of reaction and avoids the use of the cancer-suspect agent, dioxane, would be desirable.
A process for the preparation of an aqueous mixture of &egr;-caprolactam and &egr;-caprolactam precursors, including 6-aminocaproamide is disclosed in published international application WO 9835938. A process that provides a higher yield of 6-aminocaproamide would be desirable from an industrial point of view to simplify purification and provide lower amounts of waste.
SUMMARY OF THE INVENTION
There is a need to improve and overcome deficiencies of the prior processes of preparing 6-aminocaproamide such as the generation of ethanol as a byproduct, a low rate of reaction, the use of dioxane, a complicated reaction, and high amounts of waste.
In accordance with these needs, there is provided according to the present invention a process for the production of 6-aminocaproamide comprising reacting 5-cyanovaleramide with hydrogen in the presence of a metal catalyst selected from supported metal catalysts, sponge metal catalysts, homogenous catalysts, and reduced metal oxide, hydroxide, or carbonate catalysts, wherein if the catalyst is a supported metal catalyst comprising cobalt or nickel, and if the support is calcined, it is calcined before application of the nickel or cobalt.
According to the present invention, there is also provided a process further comprising reacting the 6-aminocaproamide to produce caprolactam, and polymerizing the caprolactam to form a polyamide. Furthermore, there is provided 6-aminocaproamide, caprolactam, and polyamide produced according to the processes of the present invention.
There is also provided a process for the production of 6-aminocaproamide that does not form ethanol, comprising reacting cyanovaleramide with hydrogen in the presence of a metal catalyst.
Further objects, features, and advantages of the invention will become apparent from the detailed description that follows.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a process for the production of 6-aminocaproamide by reaction of 5-cyanovaleramide with hydrogen in the presence of a metal catalyst, and optionally in a liquid solvent. 5-Cyanovaleramide may be obtained by processes known in the art. For example, 5-cyanovaleramide may be obtained by reaction of adiponitrile with water in the presence of a supported copper catalyst. See, for example, U.S. Pat. No. 5,347,033, incorporated herein by reference. 5-Cyanovaleramide can also be made by the reaction of cyanovalerate with ammonia in the presence of an alcohol, by ammonolysis of nylon 6,6, and by enzymatic process. See, for example, U.S. Pat. Nos. 5,302,756, 5,728,556, EP 178106B1, and EP 576976 respectively, each incorporated by reference. Unlike U.S. Pat. No. 4,119,665, it is not necessary to produce the 5-cyanovaleramide by a process that results in a by-product alcohol, such as ethanol.
Metal catalysts useful in the present invention can be of many types. The catalyst is used in an amount effective to catalyze the reaction. For example, sponge metal catalysts, homogenous catalysts, reduced metal oxide catalysts, and mixed metal oxide catalysts may be used. Also, supported metal catalysts may be used. The active metal can be selected from, for example, iron, ruthenium, rhodium, iridium, palladium, and platinum. Supported cobalt and nickel catalysts may also be used if they are added to a preformed support material. For example, that is, if the support is to be calcined, in contrast to the process of U.S. Pat. No. 4,119,665, the calcination occurs prior to adding the cobalt or nickel. It is advantageous to first calcine the support, so that the active metal is on the surface of the support, and hence is more readily available to catalyze the reaction. Therefore, there is not much waste of active metal since it is available on the surface for use. Also, if a preformed support is used, there can be better control of particle size. Moreover, it can be economically useful to use a preformed support, since a single support can be used to support numerous active metals.
Any desired sponge metals can be used. A sponge metal has an extended “skeleton” or “sponge-like” structure of metal, with dissolved aluminum and/or silicon and optionally contains promoters. The sponge metal catalysts may also contain surface hydrous oxides, adsorbed hydrous radicals, and hydrogen bubbles in the pores. A description of sponge metal catalysts and their preparation can be found in U.S. Pat. No. 1,628,190, which is incorporated herein by reference.
Preferred sponge metals include nickel, cobalt, iron, ruthenium, rhodium, iridium, palladium, and platinum. The sponge metal may be promoted by one or more promoters selected from the group of Group IA (lithium, sodium, and potassium), IB (copper, silver, and gold), IVB (titanium and zirconium), VB (vanadium), VIB (chromium, molybdenum, and tungsten), VIIB (manganese, rhenium), and VIII (iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum) metals. The promoter can be used in an amount useful to give desired results. For example, the amount of promoter may be any amount less than about 100% by weight of the sponge metal, preferably 0 to about 10% by weight, more preferably 1 to 5% by weight
Sponge nickel or sponge cobalt (also known as Raney® catalysts) are particularly suitable as catalysts. Sponge nickel catalysts contain mainly nickel and aluminum, the latter in the form of metallic aluminum, aluminum oxides, or aluminum hydroxides. Small amounts of other metals in elementary or in chemically bound form, such as iron and/or chromium, may be added to the sponge nickel to increase the activity and selectivity for the hydrogenation of certain groups of compounds. As mentioned above, these added metals are usually called promoters, while the catalyst is called promoted sponge nickel. It is particularly preferred to use chromium and/or iron promoted sponge nickel as a catalyst.
Sponge cobalt catalyst also contain aluminum and may contain promoters. Preferred promoters are nickel and chromium, for example, in amounts of about 2% by weight based on the weight of the catalyst.
Examples of sponge metal catalysts that are suitable include the nickel type Degussa-Huls® BLM 112W, W.R. Grace Raney® 2400, and Activated Metals® A-4000. Useful sponge cobalt catalysts include Activated Metals® P8046, Degussa Huls® BLMX 2113Z a
Allgeier Alan Martin
Harper Mark Jay
Koch Theodore Augur
Sengupta Sourav Kumar
E.I. Du Pont de Nemours and Company
Kumar Shailendra
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