H. H. Mitchell and H. C. Eckstein Oto 
Besides being an effective foam inhibitor with no detrimental 
effects, phenyl ether may be recommended for this purpose be- 
cause it can be readily synthesized at comparatively low cost. 
We have used the method of Ullmann and Sponagel? with satis- 
factory results. 
A convenient procedure is as follows: Into a1.5 liter round-bottomed flask 
are weighed 560 gm. of bromobenzene, 420 gm. of phenol, 221 gm. of KOH, 
and 3.5 gm. of copper-bronze. This mixture is heated on an oil bath at 210 
—230°C. for about 2.5 hours under a reflux condenser. We have used as 
a condenser a 30 inch glass tube of 3 inch bore, topped by a water condenser 
of equallength. Even with this arrangement it is difficult if not impossible 
to prevent some loss of bromobenzene, especially during the early stages 
of heating. The mixture is then distilled with steam. The distillate is 
separated in a separatory funnel and the heavy oil at the bottom fraction- 
ally distilled. The boiling point of phenyl ether is 252.3°C. We have 
taken off fractions from 244-261°C. for use. 
The yield may be increased greatly, at least if the steam distillation has 
not been carried to completion,‘ by extracting the residue from the steam 
' distillation, in small portions, with ether, three washings for each portion 
being sufficient. The ether extracts are then distilled. A careful and re- 
peated fractionation of the oil from the steam distillation and of the mate- 
rial extracted by ether from the residue is advantageous. After several 
fractionations it will be found that most of the material falls into two frac- 
tions; namely, from 150-168°, and from 244-261°C., the former fraction 
being bromobenzene and the latter phenyl ether. From the quantities of 
chemicals given above, we have obtained 287 gm. of phenyl ether, repre- 
senting a yield of 47.5 per cent of the theoretical, figured on the basis of 
560 gm. of bromobegnzene, or of 73 per cent when from the amount of bromo- 
benzene taken that recovered in the final fractional distillation (200 gm., 
boiling from 150-168°) is deducted. The relatively large amount of bromo- 
benzene thus recovered would suggest that the time of refluxing at 210- 
230° could be lengthened considerably to advantage. 
Phenyl ether melts at 28°C., but when in the liquid state it 
may be supercooled considerably without solidifying. We have 
observed no solidification of our product at temperatures above 
BOG. 
® Ullmann, F., and Sponagel, P., Ber. chem. Ges., 1905, xxxviii, 2211. 
4 Complete steam distillation of the above mixture would consume too 
much time. We continued the process for about 4 hours, at which time the 
condensed water was still somewhat cloudy. Our experience suggests that 
the steam distillation may well be omitted and the product recovered from 
the mixture after refluxing, by ether extraction entirely. 
