Production of aliphatic primary amines

Abstract: Disclosed is a process for preparing an unsaturated aliphatic primary or secondary amine from the corresponding unsaturated aliphatic nitrile without hydrogenating an olefinic bond in the molecule. The process employs a catalyst which is a combination of copper and a specific metal.

Description: The present invention relates to a process for preparing an aliphatic primary amine from an aliphatic nitrile. An aliphatic primary or secondary amine, especially one containing an unsaturated group, is very useful for many applications or as intermediate. The amine is generally prepared by hydrogenating an unsaturated aliphatic nitrile in the presence of a catalyst for hydrogenation. For producing the aliphatic secondary amine, the use of a copper-chromium catalyst is proposed in UK Patent 773,432. However, since the copper-chromium catalyst is poor in catalyst activity, it takes a long time to terminate the reaction. Japanese Kokai Publication (unexamined) 55-9018 proposes a nickel containing catalyst which, however, hydrogenates a unsaturated group in the molecule as well as a nitrile group. Accordingly, it is difficult to selectively produce the unsaturated secondary amine. In order to resolve the above problems, Japanese Kokai Publication (unexamined) 62-175445 discloses that the hydrogenation is carried out in the presence of a nickel containing catalyst and a carboxylic amide. In this reaction, the carboxylic amide is brought into the reaction product and is quite difficult to remove or separate from the product. For producing the aliphatic primary amine, Japanese Patent Publication (examined) 38-21353 teaches that the hydrogenation of the unsaturated aliphatic nitrile is carried out in the presence of Raney nickel or Raney cobalt as well as an alkali (alkali metal hydroxide) or ammonia. This method also hydrogenates not only a nitrile group but also an unsaturated groups. It therefore is difficult to selectively produce the unsaturated primary amine. It has been found that, when copper is combined with a specific metal and employed as catalyst for hydrogenation, an unsaturated aliphatic secondary or primary amine is selectively prepared from an unsaturated aliphatic nitrile, wherein the olefinic group remains unsaturated in the molecules. The process is applicable to the production of the aliphatic secondary or primary amine having an unsaturated group, and is also effective for producing the saturated aliphatic secondary or primary amine from the corresponding saturated nitriles. The present invention provides a process for preparing an aliphatic primary amine comprising reacting a C 8 -C 24 aliphatic nitrile with hydrogen at a temperature of from 150 to 250 °C and a hydrogen pressure of 98,06 kPa - 4.9 MPa (1 to 50 atm) (gauge pressure) in the presence of a catalyst for hydrogenation and either alkali metal hydroxide or ammonia, wherein the catalyst contains (a) copper and (e) an VIII. group platinum metal and/or (f) a IV. period transition metal except for copper in a metal weight ratio (a/e) of from 1/0.0001 to 1/0.1 and (a/f) of from 99/1 to 10/90. The catalyst for hydrogenation of the present invention comprises (a) copper and (e) a VIII. group platinum metal and/or (f) a IV. period transition metal, except copper, in a metal weight ratio (a/e) of from 1/0.0001 to 1/0.1 and (a/f) of from 99/1 to 10/90. Typical examples of the VIII group metals are platinum, ruthenium and palladium. The metal weight ratio of a/e is within the range of 1/0.0001 to 1/0.1. If the metal weight ratio is outside the above above range, it may hydrogenate the olefinic groups in the molecule, thus hydrogenation selectivity being poor. A IV. period transition metal (f) except copper, is present in a metal weight ratio (a/f) of from 99/1 to 10/90, preferably from 99/1 to 50/50. The IV. period transition metal, except copper, enhances the hydrogenation selectivity. Typical examples of the 4th period transition metals, except copper, are chromium, manganese, iron, cobalt, nickel and zinc. If the amounts of the components (e) and (f) is outside the above range, both the selectivity and activity of the catalyst are poor. The catalyst may contain (c) an alkali metal or an alkali earth metal in a metal weight ratio (a/c) of from 1/1 to 1/0.01, preferably from 1/0.5 to 1/0.01. Typical examples of the alkali metals are lithium, sodium, potassium, rubidium and cesium. Typical examples of the alkali earth metals are magnesium, calcium, strontium and barium. If the amount of the component (c) is more than 1/1 in a metal weight ratio based on the amount of (a), catalyst activity becomes poor. The catalyst may further contain (d) at least one metal selected from the group consisting of aluminum, molybdenum and tungsten. The metal weight ratio of a/d is preferably within the range of from 1/1 to 1/0.01. These metals increase catalyst activity. The metal mentioned above may be contained in the catalyst of the present invention in any form , such as the metal itself, as a metal oxide, metal hydroxide, metal salt and metal ion. In other words, the metals contained in the catalyst of the present invention are required to come into contact with the aliphatic nitrile in the reaction system, irrespective of the form in which the metal is employed. The catalyst of the present invention can be used in any form, such as in the form of the metal itself, as a metal-containing material (such as, metal oxide, metal hydroxide, metal salt and metal ion) which may be carried on a carrier. The metal contained in the catalyst may be a complex stabilized by chelation with an aliphatic carboxylic acid or a suitable ligand. The catalyst can be a combination of the above mentioned forms. It is preferred to use the metal carried on a suitable carrier, because of the stability of the catalyst metal and the resistance against, a catalyst poison. Such carriers are alumina, silica, silica-alumina, diatmaceous earth, active carbon, zeolite and the like. The metal may be preferably present in the carrier in an amount of from 5 to 70 % by weight. A method for bringing the catalyst metal on the carrier is known in the art, for example an impregnating method wherein a carrier is poured in a solution containing a suitable metal salt for impregnating; a method wherein an alkali solution containing ammonia, sodium hydroxide, sodium carbonate and the like is added to a solution containing a carrier and a catalyst metal salt to precipitate the metal salt on the carrier; a method wherein an alkali solution and a metal salt solution are simultaneously added to a carrier slurry to precipitate the metal salt on the carrier; or an ion-exchange method wherein a catalyst metal is ion-exchanged with sodium or potassium in zeolite. The reaction of the present invention can be carried out by contacting the catalyst for hydrogenation with the aliphatic nitrile. The contact can be done in an art-known method. For example, since many aliphatic nitriles are liquid in ambient temperature, the above catalyst may be simply mixed with the aliphatic nitrile. After finishing the reaction, the catalyst can be separated from the reaction product. The aliphatic nitrile employed in the present invention is a saturated or unsaturated aliphatic nitrile having 5 to 24 carbon atoms, such as capronitrile, lauronitrile, coconut oil fatty acid nitrile, beef fatty acid nitrile, stearonitrile, cleonitrile, linolonitrile, linoleonitrile, eruconitrile, behenonitrile or a mixture thereof. A nitrile having a branch chain which is prepared from a synthetic fatty acid having a branch chain can also be used. The reaction can be carried out by charging the aliphatic nitrile and the catalyst for hydrogenation in a reaction vessel having a hydrogen introducing tube, a tube for sampling and a drain tube for the produced ammonia. The amount of the catalyst is not limited, but the preferred amount is generally from 1 to 5 % by weight based on the amount of the nitrile. The reaction vessel is filled with nitrogen and then substituted for hydrogen. The hydrogen pressure is controlled within 98,06 kPa - 4,9 MPa (1 to 50 atm) (gauge pressure), preferably 5 to 30 atm during the reaction. The reaction vessel is then heated to a reaction temperature of from 150 to 250 °C, preferably from 180 to 230 °C. Ammonia produced during the reaction is continuously or intermittently drained off from the reaction vessel. After the completion of the reaction, the reaction product is distilled or filtered to separate from the catalyst. The hydrogenation is carried out in the presence of the catalyst of the present invention and either an alkali metal hydroxide (e.g. sodium hydroxide, potassium hydroxide etc.) or ammonia. The amount of the alkali metal hydroxide is from 0.05 to 1.0 % by weight based on the aliphatic nitrile. Amounts less than 0.05 % by weight do not provide hydrogenation selectivity desired. Amounts more than 1.0 % by weight lower catalyst activity. According to the present invention, a long chain unsaturated aliphatic amine can be selectively prepared employing a specific catalyst in a very small amount from the corresponding unsaturated aliphatic nitrile in a short period of time. The catalyst employed in the present invention can keep their high catalyst activity after being used several ten times. EXAMPLES The present invention is illustrated by the following examples which, however, are not construed as limiting the invention to their details. Production Example 1 A one liter flask was charged with 50 g of ion-exchanged water, 20 g of synthetic zeolite (MS-5A), 50 g of copper nitrate, 10 g of zinc nitrate and 50 mg of ruthenium chloride, and heated to 90 °C with stirring. At that temperature, 255 g of a 10 % sodium carbonate aqueous solution was added dropwise and then aged one hour. The precipitate was filtered and rinsed with water. It was then dried at 100 °C for 10 hours and baked at 500 °C for 2 hours to form a copper-zinc-ruthenium catalyst carried on synthetic zeolite. Production Examples 2 to 5 Copper-rhodium- IV. period metal (manganese, iron, cobalt or nickel)-lithium catalysts were prepared as broadly described in Production Example 1. All catalysts had a metal weight ratio (Cu/Rh/ IV. period metal/Li) of 8/0.5/1/0.5. Production Example 6 A copper-zinc catalyst was prepared as broadly described in Production Example 1, with the exception that rhodium chloride was not employed. The catalyst had a metal weight ratio (Cu/Zn) of 9/1. Examples 1 to 6 A one liter reaction vessel having a hydrogen inlet and a sampling tube was charged with 300 g of oleonitrile or stearonitrile, sodium hydroxide (0.2 % by weight) and the catalyst mentioned above and filled with nitrogen. Hydrogen was then introduced and pressured to a pressure as shown in Table 1. The reaction vessel was heated to a temperature as shown in Table 1, keeping the hydrogen pressure, and the reaction was started. After the completion of the reaction, the reaction product was filtered to separate from the catalyst. The reaction product was analyzed and the results are shown in Table 1. Comparative Examples 1 and 2 The same experiments were conducted as broadly described in Examples 1 to 6, with the conditions as shown in Table 1. The analysis and double bond retention are shown in Table 1. It is apparent that the catalysts of Examples 1 to 6 have higher activity and can more selectively produce a long-chain unsaturated aliphatic primary amine without hydrogenating the unsaturated double bond in a molecule, in comparison with Comparative Examples 1 and 2.

Claims: A process for preparing an aliphatic primary amine comprising reacting a C 8 -C 24 aliphatic nitrile with hydrogen at a temperature of 150 to 250 °C and a hydrogen pressure of 98.06 kPa - 4.9 MPa 1 to 50 atm (gauge pressure) in the presence of a catalyst for hydrogenation and either alkali metal hydroxide or ammonia, wherein the catalyst contains (a) copper and (e) an VIII. group platinum metal and/or (f) a IV. period transition metal except copper in a metal weight ratio (a/e) of from 1/0.0001 to 1/0.1 and (a/f) of from 99/1 to 10/90. The process according to Claim 1 wherein said catalyst further contains (c) an alkali or alkali earth metal in a metal weight ratio (a/c) of from 1/1 to 1/0.01. The process according to Claim 1 wherein said catalyst further contains (d) at least one metal selected from the group consisting of aluminum, molybdenum and tungsten in a metal weight ratio (a/d) of from 1/1 to 1/0.01.

Inventors: ABE HIROSHI, KATOH TOHRO, SOTOYA KOHSHIRO, TAJIMA HISAKAZU, ABE, HIROSHI, KATOH, TOHRO, SOTOYA, KOHSHIRO, TAJIMA, HISAKAZU
Applicants: KAO CORP, KAO CORPORATION
Application year: 1989
Main classification: C07C209
IPC codes: C07C209, B01J23