Patent GB-805048-A (GB)
Title: Improvements in the manufacture of phenols
Inventor: COOKE MAURICE DUDLEY
IPC: C07C37/08
Filed: 1956-04-13
Abstract: Phenols are prepared by a process comprising contacting the reaction mixture obtained by the mineral-acid catalysed decomposition of an a ,a -dialkyl acryl methyl hydroperoxide with an aqueous solution of a salt, which solution has a pH value of not more than 7, in a concentration sufficient to ensure the formation of a separate aqueous phase whereby the mineral-acid catalyst is extracted from the organic phase into the aqueous phase.  The hydroperoxides have the general formula <FORM:0805048/IV (b)/1> wherein the R's represent alkyl groups and Ar represents an aryl or alkaryl group which may contain nuclear halogen substituents. The neutral or acidic aqueous extracting solution may be prepared from alkali metal or ammonium sulphates, chlorides, phosphates or nitrates, the salt normally being that of the acid used in the catalytic decomposition of the hydroperoxide.  The salt concentration may range from 5 to 50 per cent and is preferably in the upper part of the range, the temperature then being made sufficiently high to prevent salt crystallization.  A volume ratio of aqueous phase: organic phase of 1-25 : 1 may be used in the extraction.  Batchwise or continuous methods of extraction are utilizable such as counter current extraction in a column or the passage of the two liquids through a tube under turbulent flow conditions followed by settling in a tank. The treated organic phase containing the phenol and ketone is preferably thereafter treated with sodium carbonate, advantageously used in aqueous solution in conjunction with a soluble salt such as sodium sulphate, to effect removal of small amounts of organic acids present before being distilled to recover its components.  The aqueous salt solution containing the extracted mineral acid catalyst may be used for further extraction of mineral acid catalyst preferably after removal of any dissolved phenol or ketone therein. Undue buildup of acid in the salt solution may be prevented by withdrawing part of the solution to be reused, neutralizing all or part of the acid therein, e.g. with ammonia or sodium hydroxide or phenate, and then adding it to the remainder of the solution with make-up water.  Three methods for effecting acid-extraction and adjustment of the acidity of the recycled salt solution by the above procedures are given in detail wherein the reaction mixture is derived from the decomposition of m-diisopropyl benzene dihydroperoxide and contains acetone, resorcinol, other organic compound, some water and sulphuric acid and the extractant is aqueous ammonium sulphate maintained at a pH between about 5.0 and 7.0 or the reaction mixture is derived from cumene hydroperoxide and contains acetone, phenol, other organic compounds, a little water and sulphuric acid and the extractant is aqueous sodium sulphate maintained at a pH of about 5 to 7.  Other hydroperoxides mentioned are p-cymene, sec.-butyl benzene, p-ethyl isopropyl benzene, and isopropyl naphthalene hydroperoxides and p-diisopropyl benzene dihydroperoxide.  According to the Provisional Specification the acid catalyst may be removed by extraction with any aqueous solution of an alkali metal salt in a concentration sufficient to ensure the formation of the two phases.  Specification 673,576 is referred to.