C1N2CN3CN(C2)CN1C3.C=O.[C:13]([O-])(=[O:15])C.[NH4+].[CH3:18][C:19]1[C:24]([CH3:25])=[CH:23][CH:22]=[C:21]([CH3:26])[C:20]=1[OH:27]>C(O)(=O)C>[CH3:25][C:24]1[C:19]([CH3:18])=[C:20]([OH:27])[C:21]([CH3:26])=[CH:22][C:23]=1[CH:13]=[O:15]Instead of hexamethylenetetramine as applied in Example 2A and 2B, formaldehyde and ammonium acetate in acetic acid were used for formylation as illustrated below. A 250 ml three neck round bottom flask equipped with a reflux condenser was charged with 20.4 g (0.15 mol) of 2,3,6-trimethylphenol. 100 ml acetic acid, 3.09 g (0.04 mol) of ammonium acetate and 3.243 g (0.04 mol) of formalin solution were added to it. The reaction mass was heated at 120° C. over a period of 2.5 hrs. The completion of reaction was confirmed by TLC. The reaction mass was poured into 400 ml ice cold water with stirring. The solid was filtered and washed with 2×50 ml process water. The product was dried under vacuum to afford 17 g (75%) of crude 2,3,5-trimethyl-4-hydroxy-benzaldehyde. The purification of crude product with 1% sodium hydroxide solution afforded 13 g (53%) of pure 2,3,5-trimethyl-4-hydroxyl-benzaldehyde.
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