| 2246(2,2-Methylenebis(4-methyl-6-tertiary butyl phenol))is a very valuable antioxidant. The preparation of 2246 by 2-tertiary butyl-4-methylphenol and methylal was investigated in the present study. Several kinds of catalysts including NKC-9, 001×7, solid superacid of SO42-/TiO2, DNW-1, were chosen for the synthetic process. Different ways of removing water from methylal were used. The catalyst amount, reaction time, temperature, atmospheric pressure or high pressure, the ratio of material, and other factors influencing the yield and purity of 2246 were particularly evaluated.When NKC-9 was chosen as the catalyst, the optimized reaction conditions of using methylal without water removal were as follows: 2-tertiary butyl-4-methylphenol 41.0g, NKC-9 40.0g, methylal 140.0mL, reaction temperature 47-49℃, reaction time 4h, the yield (corresponding purity) of 2246 was55.3%(99.7%), and the melting point was 130-131℃. The optimized reaction conditions of using methylal treated with CaCl2 for 4h were as follows: 2-tertiary butyl-4-methylphenol 20.5g, NKC-9 20.0g, methylal 80.0mL, reaction temperature 47-49℃, reaction time 4h, the yield (corresponding purity) of 2246 was 93.2%(91.3%), and the melting point was 115-116℃. The optimized reaction conditions of using methylal treated with CaCl2 for 3 days were as follows: 2-tertiary butyl-4-methylphenol 20.5g, NKC-9 20.0g, methylal 80.0mL, reaction temperature 38-40℃, reaction time 9h, the yield (corresponding purity) of 2246 was 95.5%(84.1%).When solid superacid of SO42-/TiO2 was chosen as the catalyst, the highest yield (corresponding purity) of 2246 gained through the method using 2-tertiary butyl-4-methylphenol 41.0g, solid superacid (calcined at 500℃for 4h) 2.0g, methylal dealt with CaCl2 for 3 days 140.0mL, reaction temperature 47-49℃, reaction time 5h was 40.0%(51.2%), and the melting point was 105-108℃.When 001×7 was chosen as the catalyst, although we changed all the conditions, no 2246 product was obtained.When DNW-1 was chosen as the catalyst, the optimized reaction conditions under atmospheric pressure were as follow: 2-tertiary butyl-4-methylphenol 20.5g, DNW-1 10.0g, methylal dealt with CaCl2 for 3 days 80.0mL, reaction temperature 54-56℃, reaction time 7h, the yield (corresponding purity) of 2246 was 92.2%(90.7%), and the melting point was 115-117℃. Under high-pressure (0.15MPa), to reach the highest yield (corresponding purity) of 98.4%(98.2%), the reaction conditions were 2-tertiary butyl-4-methylphenol 41.0g, DNW-1 10.0g, methylal dealt with CaCl2 for 3 days 110.0mL, reaction temperature 69-71℃(in the pressure kettle), reaction time 5h.
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