| 摘要 |
The method of educing 4-(3,4-dihydro-2,2,4-trimethyl-2H-1-benzopyran-4-yl) of phenol from by-products of the process of bisphenol A synthesis consists in its crystallization from an organic solvent. Characterized in that: The by-products are dissolved in an organic solvent, selected from the group of C1-C7 alcohols or ketones or aliphatic esters or their mixtures, so that the concentration of Dianin's compound in the solvent is at least at the level of 7 percent by mass, preferably 10-20 percent by mass. Then, the mixture is cooled down to the temperature of minimum 5 degrees C. After 24-120 hours, the precipitated crystals are strained and recrystallised.
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