Catalytic preparation of aryl methyl ketones using a...

Details Catalytic preparation of aryl methyl ketones using a... Catalytic preparation of aryl methyl ketones using a...

2002-01-25

2004-01-20

Richter, Johann (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Nitrogen attached directly or indirectly to the purine ring...

C544S329000, C544S334000, C556S042000, C556S045000, C556S057000, C564S305000, C564S334000, C568S306000, C568S320000, C568S321000, C568S328000

Reexamination Certificate

active

06680385

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the preparation and application of a new class of metal complexes whose general formula are depicted below:
wherein R
1
represents substituted and nonsubstituted phenyl (Ph), pyridyl, pyrimidinyl, pyrazinyl, pyrrolyl, pyrrolinyl, imidazolyl, naphthyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, indenyl, indolyl, 4-isobenzazolyl, indoleninyl, anthracyl, phenanthrolinyl or pyrrolidyl, piperidyl, cycloalkyl groups or any combination thereof. R
2
represents substituted and nonsubstituted phenyl (Ph), naphthyl, anthracyl, indenyl, cycloalkyl groups or any combination thereof. Py represents substituted and nonsubstituted pyridyl, pyrimidinyl, pyrazinyl, pyrrolyl, pyrrolinyl, imidazolyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, indolyl, 4-isobenzazolyl, indoleninyl, phenanthrolinyl, pyrrolidyl, piperidyl or any combination thereof. X and Y can be the same or different, and represent hydrogen (H), hydroxyl (OH), alkyl (R), alkoxy (RO), cycloalkyl, halogen, nitro groups or any combination thereof. Z represents a hydroxyl (OH) or negative oxygen ion (O
−
). W represents an anion such as a halide, nitrate, sulfate, acetate, trifluoroacetate, trifluoromethanesulfonate, tetrafluoroborate, hexafluorophosphorate, perchlorate, oxalate, carbonate or any combination thereof. P represents a hydrogen atom (H) or negative charge (⊖). M represents a metal ion from groups IB, VB, VIB, VIIB or VIII of the periodic table of the elements. This invention also relates the preparation of aryl methyl ketones via oxidation of ethyl arenes using one of these complexes as catalyst, and using molecular oxygen as oxidant. The improved aryl methyl ketone selectivity and improved conversion of ethyl arene provided by this invention are particularly suitable for the industrial scale production of alkyl aryl ketone compounds.
2. Prior Art
There are several methods for preparing aryl methyl ketones. Among them, the preparation of the structurally simplest acetophenone, which is produced commercially on a large scale, has been most extensively studied. The most commonly used method of preparing acetophenone is via the oxidation of ethylbenzene using cobalt acetate or cobalt cycloalkanecarboxylate type compounds as catalyst, bromide compounds as a co-catalyst in acetic acid solvent, and molecular oxygen or air as the oxidant. A significant disadvantage of this method is the strongly corrosive nature of the bromide compounds and the acetic acid solvent. This type of reaction usually requires the use of expensive corrosion-resistant equipment. Another disadvantage of this method is the low effective utilization of the reactor due to the involvement of a large quantity of the acetic acid solvent. The third disadvantage of this method is the high cost associated with the separation and recycling of the acetic acid solvent.
Yasutaka Ishii (Journal of Molecular Catalysis A: Chemical 117, pp 123-137, 1997) reported a method for the oxidation of ethylbenzene to acetophenone by using N-hydroxyphthalimide as a catalyst, cobalt acetoacetonate as the co-catalyst, and molecular oxygen as the oxidant. The acetophenone product was obtained with high yield. However, this reaction still needed to use acetic acid as solvent, and therefore had corrosion problem. The amount of co-catalyst used in the reaction system was very high (10%), thus making the catalyst system expensive.
Lei et al. reported a method for oxidizing alkyl benzene in the absence of solvent (Chinese Chemical Letters Vol. 3, No. 4, pp 267-268, 1992). In this reaction 2,2′-bipyridyl coordinated ruthenium complex was used as catalyst, and molecular oxygen or air was used as oxidant. The highest ethylbenzene conversion was only 43.8%, and the selectivity for acetophenone was only 74%.
Lei et al. also reported another method for oxidizing alkyl benzene (Chinese Chemical Letters Vol. 4, No. 1, pp 21-22, 1993) without the use of any solvent. The method employed Fe-(2,2′-bipyridyl) or Fe-(1,10-phenanthroline) as the catalyst and molecular oxygen as oxidant. When 5 mL of ethylbenzene was oxidized in the presence of 2 mg of the catalyst, the conversion of ethylbenzene was only 11.4-34.6% after 3.5 hours. The selectivity for acetophenone was only 66.2-89.8%.
When using either one of Lei's methods to prepare acetophenone, one cannot get both high turnover frequency and good acetophenone selectivity. Taking the best result from Chinese Chemical Letters Vol. 4, No.1, pp 21-22, 1993 as an example, when the conversion of ethylbenzene was 25.3% (turnover frequency 686 mol/mol catalyst-hour), the selectivity for acetophenone was 89.8%. However, the selectivity for acetophenone dropped to 67.22% when the ethylbenzene conversion was increased to 34.58% (turnover frequency 1010 mol/mol catalyst·hour). Among the reported methods for substituted ethylbenzene oxidation and the oxidation of other ethyl arenes (such as the oxidation of halo-ethylbenzene, methyl-ethylbenzene, methoxy-ethylbenzene, nitro-ethylbenzene or ethyl-naphthalene, etc.), normally a peroxide compound was used as the oxidant. The use of molecular oxygen as oxidant has not been reported.
OBJECT OF THE INVENTION
It is an object of the present invention to overcome or a substantially ameliorate at least one of the above disadvantages.
It is another object of the present invention is to provide a highly effective method for the selective preparation of methyl aryl ketones via the oxidation of ethyl arenas using molecular oxygen as the oxidant without the use of any solvent.
SUMMARY OF THE INVENTION
This invention provides the methods for the preparation of three classes of complexes with the general formula shown below:
wherein R
1
represents substituted and nonsubstituted phenyl (Ph), pyridyl, pyrimidinyl, pyrazinyl, pyrrolyl, pyrrolinyl, imidazolyl, naphthyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, indenyl, indolyl, 4-isobenzazolyl, indoleninyl, anthracyl, phenanthrolinyl or pyrrolidyl, piperidyl, cycloalkyl groups or any combination thereof R
2
represents substituted and nonsubstituted phenyl (Ph), naphthyl, anthracyl, indenyl, cycloalkyl groups or any combination thereof. Py represents substituted and nonsubstituted pyridyl, pyrimidinyl, pyrazinyl, pyrrolyl, pyrrolinyl, imidazolyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, indolyl, 4-isobenzazolyl, indoleninyl, phenanthrolinyl, pyrrolidyl, piperidyl or any combination thereof. X and Y can be the same or different, and represent hydrogen (H), hydroxyl (OH), alkyl (R), alkoxy (RO), cycloalkyl, halogen, nitro groups or any combination thereof. Z represents a hydroxyl (OH) or negative oxygen ion (O
−
). W represents an anion such as a halide, nitrate, sulfate, acetate, trifluoroacetate, trifluoromethanesulfonate, tetrafluoroborate, hexafluorophosphorate, perchlorate, oxalate, carbonate or any combination thereof. P represents a hydrogen atom (H) or negative charge (⊖). M represents a metal ion from groups IB, VB, VIB, VIIB or VIII of the periodic table of the elements.
This invention also includes the use of these complexes as catalysts for oxidizing ethyl arenes to aryl methyl ketones. The catalysts have the advantages of high ethyl arene conversion, high turnover frequency as well as high selectivity for the aryl methyl ketone products.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
The purpose of this invention is to provide a method for the selective preparation of methyl aryl ketone via oxidation of ethyl arene using molecular oxygen as the oxidant without the use of any solvent.
The method of the preferred embodiment includes carrying out the reaction at 50-300° C. at any pressure between atmospheric pressure and 10 MPa, and reacting ethyl arene with a catalyst and an oxygen-containing gas such as air or oxygen-enriched air. The concentration of the catalyst in the reaction system is in a range from 10
−6
to 5.0 mol/L, and the catalyst is a complex of the following general formula

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