Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2002-09-24
2004-04-20
O'Sullivan, Peter (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C564S427000, C568S633000, C568S733000, C585S469000, C585S457000
Reexamination Certificate
active
06723870
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for producing anthracenes.
BACKGROUND OF THE INVENTION
Anthracenes are useful production intermediates for preparing dyes, etc., and there has been known a method for producing the compound by reacting an anthraquinone with a metal hydride (
Tetrahedron Lett.
, Vol. 29, No. 52, page 699 (1988),
J. Chem. Soc. Chem. Commun.
, page 416 (1991)).
The conventional method, however, could not necessarily provide anthracenes in a good yield.
SUMMARY OF THE INVENTION
According to the present invention, an anthracene compound can be produced in a good yield.
The present invention provides:
a method for producing an anthracene of formula (II)
wherein R
1
and R
2
each independently represent a hydrocarbon group, a halogen atom, a hydroxyl group, an alkoxy group, a carboxyl group, an aryloxy group, an aralkyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an aralkyloxycarbonyl group, or an amino group optionally substituted with a hydrocarbon group; and n and m each independently represent an integer of 0 to 4,
which mothod comprises reacting a metal hydride with an anthraquinone of (I):
wherein R
1
, R
2
, m and n represent the same as defined above, and reacting the resulting reaction mixture with a primary alcohol.
DETAILED DESCRIPTION OF THE INVENTION
R
1
and R
2
of formula (I) and (II) will be explained first.
Examples of the hydrocarbon group represented by R
1
or R
2
include a hydrocarbon group having approximately C1-C8 carbon atoms.
Examples of the hydrocarbon group include:
an alkyl such as methyl, ethyl, isopropyl, n-butyl, t-butyl, n-penthyl, n-hexyl, n-heptyl, and n-octyl groups;
an aryl group such as phenyl group; and
an aralkyl group such as a benzyl group, a phenethyl group.
Examples of the halogen atom include fluorine, chloride, bromine, and iodine.
The alkoxy, aryloxy, aralkyloxy, alkoxycarbonyl, aryloxylcarbonyl, and aralkyloxycarbonyl groups represented by R
1
or R
2
include those groups that are comprised of the alkyl, aryl and aralkyl groups as defined above, and an oxy or oxycarbonyl group respectively.
Examples of the alkoxy group include, for example, methoxy, ethoxy, isopropoxy, n-butoxy, t-butoxy, n-penthyloxy, n-hexyloxy, n-heptyloxy and n-octyloxy groups.
Examples of the aryloxy group include phenoxy group.
Examples of the aralkyloxy group include, for example, benzyloxy and phenethyloxy groups.
Examples of the alkoxycarbonyl group include methoxycarbonyl, ethoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl, t-butoxycarbonyl, n-penthyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl and n-octyloxycarbonyl groups.
Examples of the aryloxylcarbonyl group include, for example, a phenoxycarbonyl group.
Examples of the aralkyloxycarbonyl group include benzyloxycarbonyl and phenethyloxycarbonyl groups.
Examples of the amino group include an amino group optionally substituted with a hydrocarbon group as defined above for the hydrocarbon group represented by R
1
and R
2
. Specific examples thereof include methyl-, ethyl-, phenyl-, or dimethyl-amino group. Anthraquinones (I) also includes an anthraquinone of formula (I) wherein R
1
and/or R
2
represent a hydroxy or carboxyl (COOH) group which is forming a salt with lithium, potassium, or sodium.
The hydrocarbon group is preferred as R
1
and R
2
, and the alkyl group is more preferred.
Examples of the anthraquinone of formula (I) include anthraquinone, 1-methylanthraquinone, 2-t-butylanthraquinone, 2,5-dimethylanthraquinone, 2-phenylanthraquinone, 2,6-dibenzylanthraquinone, 1-chloroanthraquinone, 2-bromo-6-chlororanthraquinone, 1-hydroxyanthraquinone, 2,3-dimethoxyanthraquinone, 2-methylaminoanthraquinone, 2,3-dicarboxyanthraquinone, 1,8-dimethoxycarbonylanthraquinone, and 1,8-diphenoxycarbonylanthraquinone.
Examples of the metal hydride include, for example, an alkali metal borohydride compound such as lithium borohydride and sodium borohydride. Preferred are alkali metal borohydride. The metal hydride is usually used in an amount of at least 0.5 mole, preferably, at least 2 moles per mol of the anthraquinone of formula (I) and from an economical viewpoint, 10 moles or less is preferable.
The anthraquinone of formula (I) is usually reacted with the metal hydride in an organic solvent.
Examples of the organic solvent include a secondary alcohols such as isopropanol and 2-butanol; a tertiary alcohol such as t-butanol; an aprotic polar solvent such as N,N-dimethylformamide or dimethylsulfoxide; an ether solvent such as di-isopropyl ether, diethylene glycol dimethyl ether, 1,4-dioxane, or tetrahydrofurane; a halogenated hydrocarbon solvent such as dichloromethane, dichloroethane, or chlorobenzene; an aromatic hydrocarbon such as benzene, toluene, or xylene; an aliphatic hydrocarbons such as hexane or heptane; and a mixture thereof. The organic solvent is usually used in an amount of at least about 1 part by mass but not more than about 50 parts by mass, preferably, at least about 5 parts by mass but not more than about 20 parts by weight to 1 part by mass of the anthraquinone of formula (I). Among these organic solvents, the alcohols are preferably used and more preferred are the secondary alcohol.
The anthraquinone of formula (I) is reacted with the metal hydride usually by mixing them in an organic solvent under an inert gas atmosphere such as nitrogen. The anthraquinone (I) and the metal hydride may be reacted in such a manner that they are completely dissolved in the organic solvent or are allowed to be partially dissolved in the solvent, which means that they are present partially in a solid form without being completely dissolved in the solvent.
The reaction of the present invention is usually conducted at 0° C. or higher, preferably, 50° C. or higher but not higher than 120° C. When the boiling point of organic solvent is less than 120° C., the reaction temperature is preferably set at a temperature below the boiling point. The reaction time is usually at least about 0.5 hour but not longer than about 12 hours.
As described above, the reaction mixture comprising the anthraquinones (I) with the metal hydride is obtained by mixing them, and it is then reacted with a primary alcohol by mixing the mixture and the primary alcohol in the present invention.
Examples of the primary alcohol include, for example, methanol, ethanol, 1-propanol, and 1-butanol, which can be used alone or as a combination of two or more of them. The primary alcohol is usually used in an amount of at least 0.1 part by mass, preferably, at least 0.5 part by mass but usually not higher than 5 parts by mass per 1 part by mass of the anthraquinone (I).
The mixing of the primary alcohol and the reaction mixture resulting in the step (a) is conducted, for example, by dropwise addition of the primary alcohol.
The reaction mixture is usually mixed with the primary alcohol at a temperature of 0° C. or higher, preferably, 50° C. or higher but usually not higher than 120° C. However, in the case where the boiling point of the primary alcohol or the organic solvent used in the previous reaction step is lower than 120° C., then the mixing temperature is usually set at a temperature lower than the boiling point.
The reaction is usually conducted over a period of not less than 0.2 hour but not longer than 7 hours, preferably not less than 0.3 hour but not longer than 5 hours.
After reaction by mixing was completed, the resulting reaction mixture may be kept at a temperature of 0° C. or higher, preferably 50° C. or higher and not exceeding 120° C. In the case where the boiling point of either the primary alcohol or solvent(s) used in previous reaction step is below 120° C., then the temperature is set at a temperature below the boiling point. The reaction mixture is usually kept at the temperature over a period of not longer than 5 hours.
The reaction mixture after mixing with the primary alcohol(s) is preferably further mixed with an acid. By mixing with the acid the yield of anthracene (II) can be improved. Examples of the acid include, for example, an organic acid
Kamikawa Takashi
Morimoto Junji
O'Sullivan Peter
Sughrue & Mion, PLLC
Sumitomo Chemical Company Limited
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