研究了对羟基苯甲醛在离子液体中经溴化、水解一锅法合成3,4-二羟基苯甲醛的简便方法.对羟基苯甲醛首先与离子液体[bmim]Br3进行溴化反应得到3-溴-4-羟基苯甲醛,在对羟基苯甲醛与[bmim]Br3物质的量比1:1,20℃,30min和无溶剂条件下,单溴化产物的选择性为99.7%.溴化反应产物不经分离,直接在离子液体[bmim]Br中与氢氧化钠溶液发生水解反应得到3,4-二羟基苯甲醛,在氢氧化钠用量1.25 mol·(mol对羟基苯甲醛)-1,100℃和2h条件下,产率84.7%,纯度99.3%.离子液体重复使用6次,3小二羟基苯甲醛的产率和纯度无明显降低,该方法简便易行,反应条件温和,产率高,选择性好,不使用有机溶剂,对环境友好.%A facile one-pot method for synthesis of 3,4-dihydroxybenzaldehyde from p-hydroxybenzaldehyde via bromination and hydrolysis in ionic liquid was studied. Under the conditions of the molar ratio of p-hydroxybenzaldehyde to ionic liquid 1-butyl-3-methylimidazolium tribromide ([bmim]Br3) 1:1, reaction temperature 20℃, reaction time 30 min and solvent-free, the p-hydroxybenzaldehyde was brominated with ionic liquid [bmim]Br3 to give3-bramo-4-hydroxybenzaldehyde with 99.7% selectivity; and then without separation, the product of bromination was further hydrolyzed with NaOH aqueous solution in ionic liquid 1-butyl-3-methylimidazolium bromide ([bmim]Br), which is formed from [bmim]Br3 after the process of bromination, to form 3,4-dihydroxybenzaldehyde with 84.7% yield and 99.3% purity under the conditions as follows: the NaOH dosage is 1.25 mol(mol p-hydroxybenzaldehyde)-1, reaction temperature is 100℃ and reaction time is 2 h. The ionic liquid can be reused at least six times without significant decrease of the yield and purity of 3,4-dihydroxybenzaldehyde. This method has the advantages of convenience, mild reaction conditions, good yield, high selectivity, solvent-free and environmental friendliness.
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