Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
2003-03-04
2004-02-24
Davis, Brian (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C564S398000, C564S473000
Reexamination Certificate
active
06696609
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing diamines from the corresponding dialdehydes. The diamines produced by the process of the present invention are useful as starting materials for polyamides, polyurethanes and like polymers, as well as starting materials for various chemicals.
2. Description of the Related Art
Various processes are known for producing diamines by reacting a dialdehyde with ammonia and hydrogen in the presence of a hydrogenation catalyst, as exemplified below.
(1) U.S. Pat. No. 2,636,051 discloses a process which comprises feeding a dialdehyde to a reaction vessel containing ammonia, hydrogen and a hydrogenation catalyst, at a rate which does not exceed the consumption rate of the dialdehyde, and shows an example where a diamine was obtained in a yield of 60%, with use of a catalyst of Raney nickel and a solvent of water.
(2) Japanese Patent Application Laid-open No. 17413/1993 discloses a process which comprises feeding an alcoholic solution of a dialdehyde to a reaction zone containing a hydrogenation catalyst, a solvent, hydrogen and ammonia, and shows, in its examples that a diamine was obtained in a yield of 86.9 to 91.6%, with use of a catalyst of Raney nickel and a solvent of methanol or ethanol, and that no use of such an alcohol caused the reaction liquid to polymerize, thus yielding no desired product at all.
(3) Japanese Patent Application Laid-open No. 69999/1995 (U.S. Pat. No. 5,475,141 and EP O 628 535 A1) discloses a process which comprises preparing a mixture of a dialdehyde and a diluting agent such as an alcohol while adjusting the mixing temperature at 5° C. or below, thereby suppressing formation of hemiacetal, and then feeding the mixture to a reductive amination vessel. In the examples, 1,8-octanediamine was obtained from a dialdehyde of 1,8-octanedialdehyde with a catalyst of nickel supported on silica/alumina and a diluting agent of methanol, toluene or methyl t-buthyl ether, in a yield of 95%, 90.1% or 87.8%, respectively.
(4) Japanese Patent Application Laid-open No. 196586/1995 discloses a process which comprises using as a hydrogenation catalyst a nickel supported on an inorganic oxide. In the examples, a mixture of 1,9-nonanedial and 2-methyl-1,8-octanedial as dialdehydes yielded, with use of a catalyst of nickel supported on Kieselguhr and a solvent of 1-butanol, methanol, 2-propanol, tetrahydrofuran or 1,4-dioxane, a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine in a yield of 92.6%, 93.5%, 89.0%, 92.1% or 91.2%, respectively.
(5) Japanese Patent Application Laid-open No. 130210/1998 discloses a process which comprises dissolving a dialdehyde in a lower alcohol in the presence of an amine other than ammonia in an amount of not more than 4 mole % based on the moles of the dialdehyde and then subjecting the solution to reductive amination. In the examples, mixtures of 1,9-nonanedial and 2-methyl-1,8-octanedial as dialdehydes yielded, with use of a catalyst of Raney nickel and a solvent of methanol, by addition of an amine such as triethylamine, mixtures of 1,9-nonanediamine and 2-methyl-1,8-octanediamine in a maximum yield of 95%.
(6) Japanese Patent Application Laid-open No. 310559/1998 discloses a process which comprises carrying out reductive amination with use of a solvent of an alcohol having 3 to 10 carbon atoms. In the examples, a mixture of 1,9-nonanedial and 2-methyl-1,8-octanedial as dialdehydes using a catalyst of Raney nickel yielded, with use of a solvent of n-butanol, isopropyl alcohol or n-octyl alcohol, a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine at a yield of 90.5%, 92.0% or 90.8%, respectively. In another example, there were used the same starting material, a catalyst of nickel supported on Kieselguhr and a solvent of n-butanol, to yield a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine at a yield of 97%. Still another example started from a dialdehyde of 3(4),8(9)-tricyclo[5.2.1.0]decanedicarbaldehyde with use of Raney nickel catalyst and a solvent of n-butanol, and obtained tricyclodecanedimethanamine in a yield of 91.6%.
(7) Japanese Patent Application Laid-open No. 29534/1999 (U.S. Pat. No. 5,973,208 and EP 0 878 462 B1) discloses a process which comprises carrying out the reaction, with use of a solvent of an alcohol, while adjusting the water concentration in the liquid phase in the reaction vessel within the range of 5 to 15% by weight. In the examples, a mixture of 1,9-nonanedial and 2-methyl-1,8-octanedial as dialdehydes using a catalyst of Raney nickel yielded, with use of a solvent of n-butanol, methanol or isoamyl alcohol, a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine in a yield of 96%, 95% or 95%, respectively. Another example started from a dialdehyde of 3(4),8(9)-tricyclo[5.2.1.0]decanedicarbaldehyde with use of a solvent of n-butanol, and obtained tricyclodecanedimethanamine in a yield of 96%.
The above process (1) which uses water as solvent has the problem of low yield of the desired diamine. The above processes (2) through (7) suggest that, in order to obtain a diamine at a high yield, it is suitable to use as solvent an alcohol, e.g. methanol, ethanol, 2-propanol, 1-butanol, isoamyl alcohol and n-octyl alcohol; an aromatic hydrocarbon, e.g. toluene; or an ether, e.g. methyl t-butyl ether, tetrahydrofuran and 1,4-dioxane.
The present inventors studied on the relationship between the solvent used and the reaction result and found that use of a solvent of an alkanol having at least 3 carbon atoms, an aromatic hydrocarbon such as toluene or an ether such as methyl t-butyl ether, tetrahydrofuran or 1,4-dioxane, as shown in Reference Example 1 of the present specification, leads to lower productivity and lower yields of the desired products, in comparison with reaction using a solvent of methanol or ethanol. This shows that it is most suitable, in order to produce diamines in high yield and productivity and commercially advantageously, to use methanol or ethanol as a solvent.
The present inventors then further studied how to produce diamines with use of a solvent of methanol or ethanol and, as a result, found that, under reaction conditions for synthesizing diamines, the solvent of methanol or ethanol gives rise to byproduction of a small amount of the corresponding methylamine or ethylamine, which is a primary amine having methyl or ethyl group. It was further found that these primary amines byproduced in small amounts will gradually accumulate in the alcohol recovered in a recovery process such as distillation separation, which is generally employed, upon using such an alcoholic solvent, not to dispose it after one use in view of economy and reduction of environmental load. These accumulated primary amines react with the starting material dialdehyde to form diamines with the hydrogen atoms of the amino groups replaced by methyl group or ethyl group. The resultant N-methyl or N-ethyl substituted diamines have properties such as boiling point similar to those of the desired diamine and hence can hardly be separated by distillation or like separation processes, thereby becoming impurities contained in the desired diamines. As a result, the obtained diamines will, when used as starting materials for polymers or chemicals, deteriorate the properties of the end products.
The above processes (2) through (5) and (7) never mention about the byproduction of primary amines from the alcoholic solvents used, accumulation of the primary amines in the alcoholic solvent in the course of recovery and re-use of the solvent or the accompanying formation of N-alkyl-substituted diamines, and take no countermeasures against such troubles. The above process (6), which mentions formation of N-alkyl-substituted diamines originating from the alcoholic solvents used though, never describes about selection of an optimum solvent of methanol or ethanol in view of yield and productivity as shown in Reference Example 1 of the present specification, or about any means for suppres
Suzuki Shigeaki
Tokuda Yoshihiro
Davis Brian
Kuraray Co. Ltd.
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