发明名称 |
PROCESS FOR PURIFYING CRUDE 4-AMINOPHENOL |
摘要 |
A process for the purification of crude 4-aminophenol which was prepared by the catalytic hydrogenation of nitrobenzene in aqueous sulfuric acid is described involving: adjusting the pH of an aqueous solution of crude 4-aminophenol to pH 4.0-5.0 at a temperature between 75.degree.C and 85.degree.C; mixing the aforesaid solution with toluene as the solvent, in order to extract various impurities and the dissolved nitrobenzene starting material; adjusting the pH of the resultant solution as required to maintain it at pH 4.0-5.0; allowing the resultant mixture to settle thereby forming a top organic layer and a bottom aqueous raffinate layer which raffinate contains 4-aminophenol and the by-product material, ortho-aminophenol; separating the two layers and repeatedly extracting the raffinate layer with toluene at pH 4.0-5.0 at a temperature of 75-85.degree.C until most impurities have been removed from the resultant final raffinate; adding to the resultant raffinate, a charcoal decolorizing agent and a sodium sulfite type salt, which are then removed, leaving a filtrate which contains the 4-aminophenol and also the by-product ortho-aminophenol; adjusting the pH of said filtrate to pH 6.5-8.0 and cooling it to a temperature below 10.degree.C; separating the precipitated pure 4-aminophenol from the by-product ortho-aminophenol which remains in the solution. |
申请公布号 |
CA1309109(C) |
申请公布日期 |
1992.10.20 |
申请号 |
CA19880565251 |
申请日期 |
1988.04.27 |
申请人 |
NORAMCO, INC. |
发明人 |
KAO, JAMES T.F.;RAFF, DWIGHT E., II |
分类号 |
C07C213/10;C07C67/00;C07C213/00;C07C215/76 |
主分类号 |
C07C213/10 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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