Process for preparation of 2-substituted 1,4-naphthoquinone
AssigneeNippon Shokubai Kagaku Kogyo Co., Ltd.
InventorsNoboru Sugishima, Noriaki Ikeda, Yasushi Fujii, Ryuji Aoki, Yumi Hatta
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Abstract
A process for preparation of a 2-substituted-1,4-naphthoquinone which comprises oxidizing a 2-substituted naphthalene to obtain reaction products comprising a 2-substituted-1,4-naphthoquinone and a 6-substituted-1,4-naphthoquinone; adding a diene compound to the reaction products and heating the mixture to form a Diels-Alder reaction adduct between the diene compound and the 6-substituted-1,4-naphthoquinone in the reaction products; and separating the 2-substituted-1,4-naphthoquinone from the adduct.
Claims13
A process for preparation of a 2-substituted-1,4-naphthoquinone which comprises oxidizing a 2-substituted naphthalene to obtain reaction products comprising a 2-substituted-1,4-naphthoquinone and a 6-substituted-1,4-naphthoquinone;
- adding a diene compound to the reaction products and heating the mixture to a temperature of from 50.degree. to 200.degree. C. to form a Diels-Alder reaction adduct between the diene compound and the 6-substituted-1,4-naphthoquinone in the reaction products;
- and separating the 2-substituted-1,4-naphthoquinone from the adduct.
A process for preparation of a 2-substituted-1,4-naphthoquinone which comprises the following steps, step (1) oxidizing a 2-substituted naphthalene with an acidic aqueous solution of a ceric salt;
- step (2) extracting the reaction products obtained by the oxidation reaction of step (1) and comprising 2-substituted-1,4-naphthoquinone and 6-substituted-1,4-naphthoquinone with a solvent, and separating the solvent phase from the phase of the acidic aqueous solution of the ceric salt;
- step (3) adding a diene compound to the solvent phase containing the reaction products separated in step (2) and heating the mixture to a temperature of from 50.degree. to 200.degree. C. to form a Diels-Alder reaction adduct between the diene compound and the 6-substituted-1,4-naphthoquinone;
- step (4) separating and recovering the solvent from the reaction mixture obtained in step (3);
- and step (5) removing the Diels-Alder reaction adduct from the reaction mixture after separation of the solvent to obtain the 2-substituted-1,4-naphthoquinone having a high purity.
A process for preparation of 2-methyl-1,4-naphthoquinone hydrogensulfite salt which comprises oxidizing 2-methylnaphthalene to obtain reaction products comprising 2-methyl-1,4-naphthoquinone and 6-methyl-1,4-naphthoquinone;
- adding a diene compound to the reaction products and heating the mixture to a temperature of from 50.degree. to 200.degree. C. to form a Diels-Alder reaction adduct between the diene compound and the 6-methyl-1,4-naphthoquinone in the reaction products;
- and adding an aqueous hydrogensulfite salt solution to the resulting reaction mixture to extract the 2-methyl-1,4-naphthoquinone into the aqueous phase as its hydrogen-sulfite salt.
A process for preparation of a -b 5,8-dihydro-2-substituted-anthraquinone and/or a 2-substituted-anthraquinone which comprises oxidizing a 2-substituted naphthalene to obtain reaction products comprising a 2-substituted-1,4-naphthoquinone and a 6-substituted-1,4-naphthoquinone;
- adding a 1,3-butadiene to the reaction products and heating the mixture at a temperature of from 50.degree. to 200.degree. C. to form a Diels-Alder reaction adduct between the 1,3-butadiene and the 6-substituted-1,4-naphthoquinone in the reaction products;
- separating the 2-substituted-1,4-naphthoquinone from the adduct, and oxidizing the adduct.
A method of recovering high purity 2-substituted-1,4-naphthoquinone from a mixture of 2-substituted-1,4-naphthoquinone and 6-substituted-1,4-naphthoquinone which comprises adding a 1,3-butadiene compound to the mixture, heating the mixture to a temperature of from 50.degree. to 200.degree. C. to form a Diels-Alder adduct between the 1,3-butadiene compound and the 6-substituted-1,4-naphthoquinone in the mixture;
- and separating the 2-substituted-1,4-naphthoquinone from the adduct in the mixture.
Dependencies are inferred from the claim text.