THE OXIDATION OF PHENOL. 149 



THE EFFECT OF TEMPEEATUEE UPON THE ACTIVITY OF THE PHENOL 



MOLECULE. 



Kohn and Fryer ^^ have observed that the phenol residues in the 

 distilling flasks are always colored. I have many times observed the 

 same phenomenon on distilling phenol when access to the atmospheric air 

 or oxygen was possible. When the phenol was distilled in an atmos- 

 phere of hydrogen with the apparatus shown in fig. 1, the residues 

 were always absolutely colorless when viewed by the eye. No precau- 

 tions are necessary to exclude light and the phenol in the hydrogen 

 atmosphere will remain colorless indefinitely in the sunlight. 



EXPEBIMENTAL. 



About 50 grams of pure phenol were introduced into a distilling flask which 

 was arranged with a tube reaching to the bottom, sealed in at the top of the 

 neck. The phenol from the time of its purification was protected from the light 

 and from contact with substances which might introduce impurities and the dis- 

 tilling flask was likewise protected from the diffused daylight of the room by 

 asbestos wrappings. No corks or stoppers were used in the distilling flask, glass 

 seals only being employed. ITie sample was distilled with a current of purified, 

 dry, atmospheric air slowly bubbling through the tube reaching to the bottom of 

 the flask. The air was purified by passing through the purifying chain fig. 1, 

 previously described, with the combustion furnace heated. 



The distillation was stopped when about 10 cubic centimeters of 

 phenol remained in the distilling flask. The phenol had been at the 

 boiling temperature twenty minutes, and during this time had assumed a 

 light reddish-yellow color, about the shade usually produced by a few 

 hours' exposure, in contact with atmospheric air, to the sun at a tem- 

 perature of about 40°. On changing the air current to oxygen and 

 heating to the boiling point the rate of coloration was much more 

 rapid, a brilliant red being produced in a few minutes. 



A tube of pure, dry phenol, prepared by the method of distillation in 

 hydrogen in the apparatus described, shown by fig. 1, and sealed in con- 

 tact with purified atmospheric air, was protected from the action of light 

 by heavy wrappings of tin foil, and placed in a steam bath at 100° in the 



"Loo. cit., 108, state, "The sample was therefore carefully distilled six 

 times successively from a glass retort and the distillate collected in a glass 

 receiver. The first portion of the distillate was always rejected, and a small 

 residue left in the retort in each distillation. The residue left in the retort 

 always possessed a dark pink tinge, which darkened rapidly on exposure, even 

 in blue glass bottles"; and on page 110, "The combined results of the previous 

 series of experiments show that distillation from glass vessels is really an 

 effectual means for completely purifying phenol. For our further experiments we 

 therefore distilled 'absolute' phenol under the conditions already described, and 

 in order to be well on the safe side fifteen successive distillations were made. 

 The final product, which was quite colorless, melted at 41° C. * * * During 

 the distillations the residue in each case turned pink, and on standing become red." 



