Organic compounds -- part of the class 532-570 series – Organic compounds – Four or more ring nitrogens in the bicyclo ring system
Reexamination Certificate
2000-12-14
2002-08-20
Raymond, Richard L. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Four or more ring nitrogens in the bicyclo ring system
C544S182000, C544S242000, C544S336000, C546S134000, C546S330000
Reexamination Certificate
active
06437122
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a heterocyclic nitrile by a reaction of a heterocyclic carboxylic acid or an ester thereof with ammonia.
So far, as a method for producing a heterocyclic nitrile by a reaction of a heterocyclic carboxylic acid or an ester thereof with ammonia, a method is known in which 6-methylnicotlnate and ammonia are reacted to produce 2-methyl-5-cyanopyridine in the presence of phosphorus oxychloride- [Izv. Akad. Nauk kaz. SSR, Ser. Khim. (1977), 27(5), 89-90].
Yield of 2-methyl-5-cyanopyridine in the known method is, however, only 35%, and a method in which a heterocyclic nitrite can be produced in a higher yield has been desired.
An object of the present invention is to provide a method in which a heterocyclic nitrile can be produced in a higher yield and a higher selectivity ratio by a reaction of a heterocyclic carboxylic acid or an ester thereof with ammonia.
Inventors of the present invention have conducted extensive studies to attain the above objects. As a result, they have found that a conspicuously higher yield and selectivity ratio can be attained when a gas-phase catalytic reaction of a heterocyclic carboxylic acid or an ester thereof with ammonia is conducted in the presence of a catalyst comprising an oxide of at least one element selected from copper and zinc.
Inventors of the present invention have further found that, using a heterocyclic nitrile thus produced as a starting material, a heterocyclic aldehyde can be produced effectively.
SUMMARY OF THE INVENTION
The present invention provides a method for producing a heterocyclic nitrile by a gas-phase catalytic reaction of a heterocyclic carboxylic acid or an ester thereof with ammonia in the presence of a catalyst comprising an oxide of at least one element selected from copper and zinc.
The present invention also provides a method for producing a heterocyclic aldehyde comprising a gas-phase catalytic reaction of a heterocyclic carboxylic acid or an ester thereof with ammonia in the presence of a catalyst comprising an oxide of at least one element selected from copper and zinc for producing a heterocyclic nitrile, and a catalytic hydrogenation of the heterocyclic nitrile thus produced in the presence of a hydrogenation catalyst.
EMBODIMENTS OF THE INVENTION
In the present invention, a heterocyclic carboxylic acid or an ester thereof is used as a starting material. The heterocyclic carboxylic acid usable in the present invention is a compound having a heterocycle containing at least one atom selected from a nitrogen atom, a sulfur atom and an oxygen atom as a hetero atom, and at least one carboxyl group bonded to a carbon atom in the heterocycle. Preferably, the heterocyclic carboxylic acid contains a nitrogen atom as the hetero atom in the heterocycle. Examples of the heterocycle include pyrrole ring, imidazole ring, imidazoline ring, pyrazole ring, pyridine ring, pyrimidine ring, quinoline ring, oxazine ring, pyrazine ring, triazine ring and azepine ring. Particularly preferred is a nitrogen-containing heterocyclic carboxylic acid in which the heterocycle contains only one carboxyl group and only one or two nitrogen atoms as the hetero atom, such as pyridine carboxylic acid, pyrazine carboxylic acid and pyrimidine carboxylic acid. The heterocyclic carboxylic acid in the present invention includes an acid anhydride thereof.
Examples of the ester of heterocyclic carboxylic acid usable in the present invention include an alkyl ester of heterocyclic carboxylic acid as described above. The alkyl in the alkyl ester is not particularly limited. Examples thereof include a straight chain or branched alkyl having one to four carbon atoms. Among them. methyl and ethyl are preferred.
In the method of the present invention, a catalyst comprising an oxide of at least one element selected from copper and zinc is used. The oxide of at least one element selected from copper and zinc include a copper oxide, a zinc oxide, a complex oxide of copper and zinc, and a mixture thereof. Preferably, the catalyst comprises an oxide of copper and an oxide of zinc, that is, it comprises a mixture of a copper oxide and a zinc oxide, a complex oxide of copper and zinc, or a mixture thereof. The weight ratio of copper and zinc in the catalyst containing both copper and zinc is preferably 0.05-99.5:1, more preferably 0.2-8.0:1 in terms of the ratio of copper oxide and zinc oxide.
The catalyst used in the present invention may further comprise an oxide of a metal other than copper and zinc as an additional ingredient or a promoter as long as it does not inhibit the gas-phase catalytic reaction of the present invention. Examples of the metal other than copper and zinc include barium, chromium and molybdenum, although the metal is not limited to them.
The catalyst used In the present invention can be produced according to a conventional known method for producing metal oxide catalysts. An oxide of at least one element selected from copper and zinc which is available on the market can also be used, as it is, as the catalyst usable in the present invention. The catalyst is molded into a desired shape, such as powder, column, cylinder, sphere, tablet, to be used in the gas-phase catalytic reaction of the present invention.
Copper compounds and zinc compounds usable as a starting material for producing the catalyst in the present invention are not particularly limited. Examples thereof include complexes, acetates, carbonates, halides, hydroxides, nitrides, ammonium salts, phosphates, sulfates, oxalate, lactates, formates and oxides of copper and zinc.
An oxide of an element selected from copper and zinc can be used as the catalyst as it is. The oxide may be supported on an inert carrier commonly used as a carrier for a conventional catalyst. Examples of the carrier include oxides of silicon, titanium, zirconium or aluminum. Among them an oxide of silicon is particularly preferred.
The gas-phase catalytic reaction of the present invention is usually conducted by feeding a heterocyclic carboxylic acid or an ester thereof and ammonia in a reactor where a catalyst described above has already been charged. (Hereinafter, the term “heterocyclic carboxylic acid” includes not only a heterocyclic carboxylic acid but also an ester.) Amount of ammonia is usually about 1-100 mol, preferably 2-20 mol, per 1 mol of the heterocyclic carboxylic acid.
When a heterocyclic carboxylic acid having a high melting point, such as pyridine carboxylic acid, is used in the present invention, it is preferred that the heterocyclic carboxylic acid is dissolved in a suitable solvent. since it can be easily fed in a reactor with a simple apparatus and a simple operation. The solvents is stable during the gas-phase catalytic reaction of the present invention and inert against the heterocyclic carboxylic acid, ammonia and heterocyclic nitrile. For example, when the heterocyclic carboxylic acid is a nitrogen-containing heterocyclic carboxylic acid, such as pyridine carboxylic acid, or an ester thereof, water, pyridine bases such as pyridine, 2-picoline, 3-picoline and 4-picoline, aromatic hydrocarbons such as toluene and xylene, and the like can be used as the suitable solvent. The solvent is used in an amount so that content of the heterocyclic carboxylic acid in the solution is usually 5-70% by weight, preferably 10-30% by weight.
In the gas-phase catalytic reaction of the present invention, an inert gas such as nitrogen, helium and water vapor may be used as a diluent. Among the inert gas, nitrogen is preferred. When a diluent is used, amount of the diluent is usually 0.1-100 mol, preferably 1-40 mol per 1 mol of the heterocyclic carboxylic acid.
The gas-phase catalytic reaction of the present invention can be conducted in either a fixed-bed reactor or a fluidized-bed reactor. When a fixed-bed reactor is used, the catalyst of the present invention is packed in a reactor tube and the portion in the tube where the catalyst is packed (catalyst packed portion) is heated usually at 250-550° C., preferably
Kimura Manabu
Matsubara Mitsuhide
Shiomi Yasuhiro
Shoji Takayuki
Balasubramanian Venkataraman
Koei Chemical Company, Limited
Raymond Richard L.
Stevens Davis Miller & Mosher L.L.P.
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