Method of purification of dihydric phenols
A dihydric phenol, purification process technology, applied in the field of purification of methyl hydroquinone, can solve the problems of increasing color, reducing molecular weight growth, reducing transparency, etc.
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Embodiment 1-2
[0048] Examples 1-2: These examples provide methods for the purification of methylhydroquinone using activated carbon as an adsorbent.
[0049] Crude MeHQ was purified using activated carbon from Norit corporation using the method described above. The solvent system used in Example 1 is a mixture of methyl isobutyl ketone (MIBK; 150 milliliters) and toluene (150 milliliters); the solvent system used in Example 2 is MIBK (150 milliliters) and petroleum ether (150 milliliters). ml) mixture. Different amounts (weight percent) of activated carbon were used in Examples 1 and 2. The results for metal ion concentrations (expressed in ppb levels) in the purified MeHQ are shown in Table 2 below.
[0050] Table 2
[0051]
Embodiment 3-9
[0052] Examples 3-9: These examples provide methods for the purification of methylhydroquinone using silica as an adsorbent.
[0053] Crude MeHQ was purified using activated carbon from Norit corporation using the method described above. The solvent system used in Example 1 is a mixture of methyl isobutyl ketone (MIBK; 150 milliliters) and toluene (150 milliliters); the solvent system used in Example 2 is MIBK (150 milliliters) and petroleum ether (150 milliliters). ml) mixture.
[0054] The procedure used to purify crude MeHQ using silica in Examples 3-6 was the general procedure described above for purification. The method used in Examples 7-9 involved dissolving MeHQ in toluene at reflux temperature and stirring the silica for 1 hour at the same temperature. The solution was then cooled to 80°C before adding acetone. The silica was then filtered off, and the filtrate was concentrated to obtain MeHQ. Table 3 below lists the different amounts of silica and the mesh size o...
Embodiment 10-13
[0057] Examples 10-13: These examples provide methods for the purification of MeHQ using water-washed silica and acid-washed silica (ie, modified silica) as adsorbent materials.
[0058] Preparation of water-washed silica: reflux silica (100 g) with 500 ml of water for about 30 minutes, filter, and dry in an oven at 120° C. to obtain water-washed silica.
[0059] Preparation of acid-washed silica: reflux silica (100 g) with 500 ml of 1N hydrochloric acid for about 30 minutes, filter, and wash with water until the pH of the filtrate is neutral. The silica was then dried in an oven at 120°C to obtain acid-washed silica.
[0060] The difference in metal ion concentration (expressed in ppb levels) in commercial silica and silica after water or acid washing is shown in Table 4 below.
[0061] Table 4
[0062] source Fe Na Zn mn Ca raw materials for washing 24700 442900 1900 700 273700 Silica after washing 8500 342400 <10
400 148100 p...
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