116 IOWA ACADEMY OF SCIENCES. 



THE HIRSCH-H0FFMEI8TER METHOD. 



The method as carried out by Hirsch was as follows: A 

 90 per cent solution of phenol was warmed on a water bath 

 in a flask fitted with a return condenser and the diazoben- 

 zene chloride solution added through the reflux condenser 

 by means of a separating funnel with sufficient rapidity to 

 cause an active, but not too violent, reaction. When all 

 was added the temperature was finally raised to 90°. The 

 resulting solution was salted out with a concentrated solu- 

 tion of sodium chloride and the liquid precipitate fraction- 

 ated by distillation. The portion boiling above 200° C was 

 dissolved in toluene and washed with a solution of sodium 

 hydroxide. This solution on being fractionated yielded 

 phenyl ether, boiling between '^60° and 290° C, and a neu- 

 tral oil in small quantity boiling between 820° and 850° C, 

 which he supposed to be diphenyl phenyl ether, 

 Ce Ho — O-C12HC)., although he did not analyze it. He 

 states that under certain circumstances he obtained a 

 yield of phenyl ether equal in weight to 50 per cent of the 

 aniline used. He did not, however, describe the circum- 

 stances under which he obtained it. 



I carried out the process in all respects essentially like 

 the above, except that no return condenser was found 

 necessary, and that part of the distillate containing the 

 phenyl ether was not dissolved in toluene for washing with 

 caustic soda, but was washed directly with the sodium 

 hydroxide solution. No loss of phenyl ether could have 

 taken place, as the soda solution was very weak, and 

 phenyl ether is almost entirely insoluble in water. It is 

 soluble, however, in a very strong solution of sodium pheno- 

 late, but is precipitated on adding a considerable amount of 

 water. The degree of dilution of the sodium phenolate 

 solution would entirely prevent any appreciable loss by 

 this method of washing. Three experiments were made, 

 and in each case a large quantity of phenol was recovered. 

 First experim en t : 



