Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2001-07-19
2002-11-05
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S571000, C568S573000
Reexamination Certificate
active
06476276
ABSTRACT:
TECHNICAL BACKGROUND
The process of oxidizing hydrocarbon by a gas containing oxygen in the absence of a catalyst to prepare corresponding hydroperoxides is known as autoxidation technology. However, in this reaction, it is necessary to raise the reaction temperature to increase the rate of accumulation of hydroperoxides. Nevertheless, when the reaction temperature is raised to increase the rate of accumulation, the reaction product hydroperoxide is thermally decomposed, resulting in a decline in its selectivity. In other words, since there was such relationship between the rate of accumulation and selectivity that as either one goes up, the other goes down, it was difficult to maintain both of them at high levels.
Attempts have been made to oxidize hydrocarbon in the state of gas containing oxygen by a catalyst to produce an effect on the rate of accumulation and/or selectivity in producing corresponding hydroperoxides (Japanese Patent Publication SHO 55-50020, for example).
The inventors of the present invention firmly believed that there should be a way to achieve high selectivity, while overcoming the relationship between the rate of accumulation and selectivity and maintaining a commercially viable rate of accumulation at the same time. With this belief, the inventors continued research assiduously. As a result, the inventors successfully made an invention to solve the problem.
In the course to the invention, inventors found that a oxidation of a hydrocarbon by a gas containing oxygen in the presence of a specific compound is effective for converting it to the corresponding hydroperoxides.
Specifically, the present invention provides a method for oxidizing hydrocarbon by a gas containing oxygen thereby to prepare corresponding hydroperoxides at a high selectivity.
DISCLOSURE OF THE INVENTION
The process for preparing hydroperoxides by the present invention is based on the attainment of a very high selectivity possible by the use of a compound capable of capturing radicals as a specified compound in the process of oxidizing hydrocarbon by a gas containing oxygen. The present invention is characterized by oxidizing hydrocarbon by a gas containing oxygen in the presence of a compound that can capture radicals and converting it selectively to corresponding hydroperoxides.
THE BEST MODE OF THE INVENTION
Examples of the starting material hydrocarbon include paraffin having secondary carbon, olefin, cycloparaffin and arylalkyl hydrocarbon. Specific preferable examples of the starting material include, but are not limited to, isobutene, etc. as paraffin having secondary carbon; pentene, isobutene, etc. as olefin; cyclopentane, cyclohexane, etc. as cycloparaffin; and cumene, cymene, etc. as arylalkyl hydrocarbon.
The compound represented by the following general formula (I) may be cited as an example of the arylalkyl hydrocarbon:
Compound of the general formula (I):
(wherein P and Q stand for hydrogen or the alkyl group, which may be the same or different from each other; t stands for a whole number of 1 to 3; and Ar stands for the aromatic hydrocarbon group of the t value.)
In the general formula (I), it is preferable that at least either of P and Q is the alkyl group, especially preferable that both of them are alkyl groups. Especially the methyl group is preferable as the aforementioned alkyl group. Further, a hydrocarbon group having the t value that can be derived from benzene, naphthalene, biphenyl, diphenyl ether, etc., preferable a hydrocarbon group of the t value that is derived from benzene or naphthalene, may be cited as examples of the aromatic hydrocarbon group.
Therefore, in the present invention, preferable examples of the arylalkyl hydrocarbon include, but not limited to, diisopropylbenzenes such as cumene, cymene, m-diisopropylbenzene and p-di-isopropyl benzene, triisopropylbenzenes such as 1,3,5-tri-isopropylbenzene, ethylbenzene, sec-butylbenzene, sec-butylethylbenzene, isopropylnaphthalenes, diisopropylnaphthalene such as 2,6-diisopropyl naphthalene, isopropyl diphenyls, diisopropylbiphenyls such as 4,4′-diisopropylbiphenyl, and mixtures of not less than two of these. Cumene is most preferable.
The compound of the present invention that can capture radicals refers to a compound having the ability to capture radicals, and it does not matter whether the compound itself possesses such ability or such ability is given to the compound under reaction conditions.
Examples of the compound of the present invention that can capture radicals include radicals of oxygen, nitrogen, phosphorus, sulfur, carbon and silicon, and the compounds that form these radicals in the reaction system.
In the preparation of the present invention, either those radicals which are stable at room temperature or those compounds which form radicals under reaction conditions may be used.
In the reaction of oxidizing hydrocarbon by a gas containing oxygen, various by-products are formed. In the case of the example of the autoxidation of cumene, dimethylphenylcarbinol, acetophenone and dicumylperoxide may be cited as examples of such by-products. It is presumed that there are alkyl radicals such as cumyl radical and cumenehydroperoxy radical, hydroxy radical, etc. present in the process of reaction. It is presumed in the present invention that the compound that can capture radicals acts on these radicals in some respects, such as capturing the radicals inducing the reaction of the formation of such by-products, and consequently the selectivity of the hydroperoxide corresponding to the raw material hydrocarbon is improved.
In selecting the compound that can capture radicals in the present invention, it is possible to use the difference in the SOMO (single occupied molecular orbit) energy level (&Dgr;&egr;(SOMO)) between the radical of or derived from said compound that can capture radicals, and the radicals to be captured. The SOMO energy level is calculated by the method as described below. It is desirable to select such compound capable of capturing radicals that the difference in the SOMO energy level, &Dgr;&egr; (SOMO), is normally 0 to 10 eV, preferably 0 to 4 eV, more preferably 0 to 1 eV.
For example, it is desirable to select such compound capable of capturing radicals in the present invention that its relationship with the radical (formula I-2 below) corresponding to the hydrocarbon to be oxidized is as follows:
&Dgr;&egr;(
SOMO
)=|&egr;
a
(
SOMO
)−&egr;
b
(
SOMO
)|=0 to 10 eV
wherein &egr; a (SOMO) stands for the SOMO energy level of the compound cable of capturing radicals or the radical formed therefrom, and &egr; b (SOMO) stands for the SOMO energy level of the radical corresponding to the hydrocarbon to be oxidized.
(wherein P and Q, standing for hydrogen or the alkyl group, may be the same or different from each other; t stands for a whole number of 1 to 3; and Ar stands for the aromatic hydrocarbon group of the t value.)
&egr; (SOMO) Calculation Method
The structural calculation of a radical is made by a semiempirical molecular orbit method (MNDO-PM3 method: MOPAC program) to calculate &egr; (SOMO).
The &egr; (SOMO) of those which are not a radical is determined by the structural calculation of the corresponding radical.
As the aforementioned &Dgr;&egr; (SOMO) becomes lower, the hydrocarbon radical is easier to capture. The &Dgr;&egr; (SOMO) is normally in the range of 0 to 10 eV, preferably 0 to 4 eV, more preferably 0 to 1 eV.
The use of a compound having a proper value of &Dgr;&egr; (SOMO) has the characteristic that in comparison with the case of adding no such compound, the selectivity goes up over the selectivity of hydroperoxide in other reaction at the same rate of accumulation. Because of this, the use of such compound enables hydrocarbon to be converted at high selectivity and at a high concentration.
Oxygen radical and a compound that forms oxygen radical in the reaction system can be cited as one specific example of the compound that can capture radicals.
As the oxygen radical of the present invention, the compound represented
Fujita Terunori
Hirokane Nobuya
Kamimura Makoto
Kato Koji
Kuroda Hiroshi
Birch & Stewart Kolasch & Birch, LLP
Mitsui Chemicals Inc.
Vollano Jean F.
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