Isolation And Application Of Mixed Cresol

1、 The separation of mixed cresolCrystallization temperature using temperature 8 ℃, maintaining stirring speed 400r/min in the crystallization process, With a purity of 98.10% m-cresol (1% p-cresol) through 2-3 times melt crystallization process to efficiently purified m-cresol content of 99.72%, the single crystallization yield of about 50%, and may be recovery crystallization mother liquor cresol by similar method to crystallization. The separation efficiency of the melt crystallization is significantly higher than the separation efficiency of distillation (the purity increase of about 0.2%), can applicable to the separation of more than 98% purity mixed cresol industrialization.2、 Synthesis of 4-methyl catecholMagnesium methanol optimum conditions, the ratio of n (P-cresol):n (Methanol magnesium):n (Polymerization formaldehyde)= 1.0:1.2:3.0, toluene as solvent, temperature 95 ℃, the phenolic hydroxyl ortho-formylation reaction to obtain the corresponding product of 5-methyl-salicylaldehyde, yield over 78%. Crude 5-methyl salicylaldehyde through Dakin oxidation generate of 4-methyl catechol, ethylene glycol dimethyl ether and water as mixed solvent, material ratio of n (5-methyl salicylaldehyde):n (H2O2):n (NaOH)= 1.0:1.5:2.2, the yield of over 98%, total yield compared to literature increased by 10%.After acetic anhydride method to optimize the process conditions, p-cresol as a starting material, the acetylation reaction to generate p-Toylacetate, which material ratio of n (P-cresol):n (Acetic anhydride):n (Concentrated sulfuric acid)= 1:1.05:0.001,120 ℃～ 140 ℃ refluxed 3.5h, more than 98% yield. The resulting methyl ester was used directly in the next step phenol rearrangement reaction, in a high boiling inert solvent of chlorobenzene by Fries rearrangement reaction to give 2-hydroxy-5-methyl acetophenone, n (Mofetil):n (AICl3)= 1:1.1, more than 96% yield. By changing the order of addition of materials to solve the security problems amplification process. The crude product thus obtained 2-hydroxy-5-methyl acetophenone, by n (2-hydroxy-5-methyl acetophenone):n (H2O2):n (NaOH)= 1:1.5:2.2 ratio of feeding, after alkaline salt,-10℃ to -5℃ Dakin oxidation at low temperature, after completion of the reaction, the reaction solution by reduction, acidified, extracted and concentrated to give crude product, by distillation get pure 4-methyl catechol, yield more than 90%, total yield compared to the previous increase of about 15%.Above experimental has the following features:reproducibility stable, green, readily available raw materials low production cost, mild reaction conditions, low requirement on equipment, simple operation, less side effects, high yield, etc,and has been applied to industrial production.