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A mixture of 2,5-dimethylphenol (0.133 mol), phthalic anhydride (0.074 mol), reaction medium (0.416 mol), and Lewis acid (0.029 mol), was stirred and heated at 90° C. for 5 hours. The reaction mixture was cooled to room temperature and added to ice-water mixture when the product precipitated. The product was filtered, thoroughly washed with water and dried. Recrystallization from methanol with charcoal treatment furnished pure 3,3-bis-(4-hydroxy-3,6-diimethylphenyl)-1-(3H)-isobenzofuranone as pale yellow crystals in 85percent yield. IR (KBr): 3393, 1729, 1611 cm-1. 1H-NMR (DMSO-d6): δ 9.40 (s, 2H, 2OH), 1.95 (s, 12H, 4CH3), 6.59-6.63 (m, 4H, aromatic), 7.46-7.91 (m, 4H, aromatic) ppm. Mass spectra: m/z 374 (M+).
Reference:
[1] Patent: US2006/222601, 2006, A1, . Location in patent: Page/Page column 25
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