Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1994-03-10
1995-05-09
Prescott, Arthur C.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
502261, 560231, 560232, 562607, C07C 5308, C07C 5116, B01J 3116, C07B 6100
Patent
active
054141109
DESCRIPTION:
BRIEF SUMMARY
This application was filed under 35 U.S.C. 371, based on Internal Application No. PCT/JP93/01282 filed Sep. 9, 1993 with priority date Sep. 10, 1992.
FIELD OF THE INVENTION
The present invention relates to a novel Ru-Sn hetero-polynuclear complex useful as a catalyst and a process for producing acetic acid and/or methyl acetate in the presence of the complex by using methanol, methyl formate or formaldehyde as a starting material.
RELATED ART
Acetic acid has been industrially produced in a large amount by the methanol carbonylation method, i.e., so-called Monsanto's method. In this method, methanol is reacted with carbon monoxide in a liquid phase in the presence of a catalytic system containing a rhodium catalyst and an iodide.
However, it is necessary in these methods to use rhodium, which is very expensive. Further, the conditions of location of the factory are restricted because it is necessary to obtain carbon monoxide of a high purity. Furthermore, there is a problem that methyl iodide, which is used as an iodide, corrodes the apparatus. In addition, since the above-mentioned reaction is usually effected in a liquid phase system containing water, the recovery of the acetic acid thus formed requires much energy.
Meanwhile, there has been proposed the use of an Ru-Sn heteronuclear cluster (a polynuclear compound) containing an anion comprising [Ru(SnCl.sub.3).sub.5 L].sup.3- (wherein L represents a ligand) as a catalyst for producing acetic acid and methyl acetate from methanol through a one-stage reaction in a liquid phase [Sumio Shinoda and Tetsu Yamakawa, "One-step Formation of Methyl Acetate with Methanol used as the Sole Source and Catalysis by Ru.sup.II -Sn.sup.II Cluster Complexes", J. Chem. Soc., Chem. Commun., p.p. 1511-1512 (1990)].
However, the above-mentioned heteronuclear cluster has a solubility in methanol as small as about 0.05 mM. In addition, since the above heteronuclear cluster is an anionic complex, the solubility of the above heteronuclear cluster is smaller not only in the acetic acid formed but also in common organic solvents. Thus, it is impossible to elevate the concentration of the catalyst, and therefore, the reaction rate also can not be enhanced. Furthermore, it is sometimes observed that formaldehyde is formed by the dehydrogenation of methanol and the metal contained in the catalyst is reduced and precipitated by the formaldehyde, which causes the deactivation of the catalyst within a short period of time. In particular, the catalyst is liable to be deactivated when reacted at a high temperature.
On the other hand, there have also been known CpRu(PR.sub.3).sub.2 L and CpRu{P(OR.sub.3)}.sub.2 .sup.L (wherein Cp represents a cyclopentadienyl group which may be substituted; R represents an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group; and L represents a specific monovalent anion ligand) as a complex containing Ru [S. G. Davies, et al., Adv. Organomet. Chem., 30, 1 (1990)]. These complexes are deemed to be highly stable in structure and, therefore, there is a possibility that these Complexes can be used as a catalyst in a reaction at a relatively high temperature.
Further, a method for synthesizing CpRu(PPh.sub.3).sub.2 Cl, which is one of these complexes, is described in M. I. Bruce, et al., Inorg. Synth., 28, 270 (1990) and a method for synthesizing CpRu(PPh.sub.3).sub.2 SnCl.sub.3, which is one of these complexes, is described in T. Blackmore, et al., J. Chem. Soc. A, 2376 (1971).
However, there has been clarified so far no catalyst which is useful in the production of acetic acid and/or methyl acetate from, for example, methanol and free from any of the above-mentioned problems.
Accordingly, it is an object of the present invention to provide a novel catalyst which has a high catalytic activity and is useful for producing acetic acid and/or methyl acetate from methanol.
It is another object of the present invention to provide a process for producing acetic acid and/or methyl acetate through a one-stage reaction starting with methanol wherein a
REFERENCES:
patent: 4626334 (1986-12-01), Ohe et al.
patent: 5214184 (1993-05-01), Matuzaki et al.
patent: 5334769 (1994-08-01), Ferrero et al.
1 C4 37 One-Step Formation Reaction (4) of Acetic Acid (Methyl Acetate) with Methanol Used as the Sole Source . . . , Institute of Industrial Science, Univ. of Tokyo, and English translation (1990).
1 C4 38 Conversion Reaction of Methanol with Supported-Ru(II)-Sn(II) Heteronuclear Cluster . . . , Institute of Industrial Science, Univ. of Tokyo, and English Translation (1990).
Daicel Chemical Industries Ltd.
Prescott Arthur C.
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