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With sulfuric acid; dihydrogen peroxide; sodium sulfite; In acetone; |
EXAMPLE 4 500 g (1.194 moles) of the p-isopropenyl phenol solution obtained in Example 1, 132.4 g (1.168 moles) of 30% aqueous hydrogen peroxide and 29.2 g of 60% sulfuric acid were maintained respectively at about 33 C., and over the course of about 5 hours, simultaneously and continuously added dropwise to a flask and mixed. The reaction was an exothermic reaction. By cooling, the temperature of the inside of the flask was maintained at 35 C. After the addition, the mixture was stirred for 1 hour, and then 23.14 g of sodium sulfite was added as a saturated aqueous solution to neutralize the sulfuric acid and decompose the unreacted peroxide. The reaction mixture was allowed to stand to separate it into two layers. The aqueous layer was separated. The organic layer was extracted with 900 ml of hot water each time. The water extracts containing acetone were combined, concentrated, and cooled. The resulting hydroquinone crystals were separated by filtration, and dried to afford 124.0 g of hydroquinone having a purity of 99.0%. Hydroquinone and sodium sulfite in the filtrate were neutralized, and hydroquinone in the separated aqueous layer was recovered. |
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With sulfuric acid; dihydrogen peroxide; sodium sulfite; In acetone; |
COMPARATIVE EXAMPLE 2 111.4 g (0.266 mole) of the p-isopropenyl phenol solution obtained in Example 1, 39.1 g (0.345 mole) of 30% aqueous hydrogen peroxide and 4.87 g of 64.1% sulfuric acid were maintained at about 35 C., and over the course of about 5 hours, simultaneously and continuously added dropwise to a flask and mixed. The reaction was an exothermic reaction. By cooling, the temperature of the inside of the flask was maintained at 35 C. After the addition, the mixture was stirred for 1 hour, and then, 17.1 g of sodium sulfite was added as a saturated aqueous solution to neutralize the sulfuric acid and decompose the unreacted peroxide. The reaction mixture was allowed to stand to separate it into two layers. The aqueous layer was separated. The organic layer was extracted four times with 150 ml of hot water each time. The water extracts containing acetone were combined, concentrated, and cooled. The resulting hydroquinone crystals were separated by filtration, and dried to afford 24.0 g of hydroquinone having a purity of 70%. Hydroquinone and sodium sulfite in the filtrate were neutralized, and hydroquinone in the separated aqueous layer was recovered. |
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With sulfuric acid; dihydrogen peroxide; sodium sulfite; In acetone; |
COMPARATIVE EXAMPLE 3 300 g (0.716 mole) of the p-isopropenyl phenol solution obtained in Example 1, 97.2 g (0.858 mole) of 30% aqueous hydrogen peroxide and 49.1 g of 50% sulfuric acid were maintained at about 50 C., and over the course of about 5 hours, simultaneously and continuously added dropwise to a flask and mixed. The reaction temperature was maintained at 50 C. After the addition, the mixture was stirred for 1 hour, and then 53.2 g of sodium sulfite was added as a saturated aqueous solution to neutralize the sulfuric acid and decompose the unreacted peroxide. The reaction mixture was allowed to stand to separate it into two layers. The aqueous layer was separated. The organic layer was extracted five times with 400 ml of hot water each time. The water extracts containing acetone were combined, concentrated, and cooled. The resulting hydroquinone crystals were separated by filtration, and dried to afford 65.4 g of hydroquinone having a purity of 75%. Hydroquinone and sodium sulfite in the filtrate were neutralized, and hydroquinone in the separated aqueous layer was recovered. |
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With sulfuric acid; dihydrogen peroxide; sulphurous acid; In acetone; |
EXAMPLE 5 500 g (1.194 moles) of the p-isopropenyl phenol solution obtained in Example 1, 134.0 g (1.182 moles) of 30% aqueous hydrogen peroxide, and 31.1 g of 60% sulfuric acid were maintained respectively at about 30 C., and over the course of about 5 hours, simultaneously and continuously added dropwise to a flask and mixed. The reaction was an exothermic reaction. By cooling, the temperature of the inside of the flask was maintained at 32 C. After the addition, the mixture was stirred for 1 hour. The concentrations of the hydrogen peroxide and the hydro-peroxide of p-isopropenyl phenol in the reaction system were 0.03%, and 0.05%, respectively. Then, 0.61 g (1.2 molar times the amount of the remaining peroxide) of sulfurous acid gas was added to decompose the remaining peroxide. The reaction mixture was allowed to stand to separate it into two layers. The aqueous layer was separated. The organic layer was extracted five times with 900 ml of hot water each time. The water extracts containing acetone were combined, concentrated, and cooled. The resulting hydroquinone crystals were separated by filtration, and dried to afford 125.0 g of hydroquinone having a purity of 99.1%. Hydroquinone in the separated aqueous layer was recovered. |
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With sulfuric acid; dihydrogen peroxide; In water; acetic acid; acetone; |
EXAMPLE 1 A solution of 2.44 g (0.0135 mole; purity 74.8 percent by weight, remainder of said material being dimer and other oligomers, said material having been prepared as described below) of p-isopropenylphenol in 20 ml of glacial acetic acid was stirred while 1.81 ml (0.018 mole) of 30 percent aqueous hydrogen peroxide was added in one portion. The resulting mixture was stirred and cooled to approximately 8 C. and 0.05 g (0.0005 mole) of concentrated sulfuric acid was added. An exothermic reaction ensued and no attempt was made to control the temperature. The maximum temperature attained was 40 C. The resulting black mixture was allowed to cool to 25 C. and was then poured into 100 ml of water. The aqueous mixture was extracted with six portions, each of 50 l ml of ether, and the ethereal extracts containing acetone were combined and dried over anhydrous magnesium sulfate. The dried solution was filtered and the filtrate was evaporated to dryness. The residue was washed with chloroform and then dried in vacuo to give 1.61 g of hydroquinone in the form of a light tan solid having a melting point of 161 to 168 C. |
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With sulfuric acid; dihydrogen peroxide; In diethyl ether; acetic acid; |
EXAMPLE 6 A solution of 3.25 g of p-isopropenylphenol (75 percent pure: prepared as described in Example 1; 0.014 mole) in 10 ml of anhydrous diethylether was maintained at 0 C. and treated with 0.85 ml (0.018 mole) of 50 percent aqueous hydrogen peroxide. To the resulting mixture was added 0.1 ml of concentrated sulfuric acid and then, after allowing the mixture to stand for 40 minutes, a second portion of concentrated sulfuric acid. The resulting product separated into two phases but the addition of 3 ml of glacial acetic acid caused the reformation of a single phase. The resulting product was extracted with ether, and the ethereal extract was dried over anhydrous magnesium sulfate and evaporated to dryness. There was thus obtained 1.72 g of crude hydroquinone which was shown by ultraviolet spectroscopy to have a purity of 57 percent. |
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With sulfuric acid; In (2S)-N-methyl-1-phenylpropan-2-amine hydrate; acetic acid; |
EXAMPLE 9 A solution of 2.44 g (0.014 mole; 78 percent pure) of p-isopropenylphenol in 20 ml of glacial acetic acid and one drop of concentrated sulfuric acid was cooled in ice water and 1.24 g (0.018 mole) of t-butyl hydroperoxide was added dropwise with stirring over a period of 10 minutes. The temperature of the reaction mixture rose to 30 C. When the temperature had subsided, the mixture was diluted with water and extracted with ether. The ethereal extract was dried over anhydrous magnesium sulfate and the dried solution was evaporated to dryness. There was thus obtained 0.5 g of crude hydroquinone. |
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