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IOWA ACADEMY OF SCIENCE 
phenol. "When the solution w£is cooled, the yellow oil which 
formed was treated with an excess of dilute potassium hydrox- 
ide solution. There was instant reaction, though apparently no 
large amount of heat was developed. After being stirred for 
five minutes the oil solidified and was broken up with a stirring 
rod and allowed to stand. It was then filtered and washed with 
water. The amount of phthalein formed was small. On crys- 
tallizing from alcohol a melting point of 115° was obtained, 
but careful recrystallization from benzene, glacial acetic acid, 
and alcohol in order, gave a melting point of 123°. This identi- 
fied it as the diphenyl ester, as will be shown later. 
The third method is the one which was used practically for 
the preparation of the diphenyl ester for analysis. It consisted 
in treating the acid chloride with a mixture of pyridine and 
phenol. Two grams of phenol and an equal amount of pyridine 
were mixed in a small beaker and the powdered acid chloride 
added. At this point in the preparation occurred the only dif- 
ference which was noticed between the action of the unsyni- 
metrical and the symmetrical acid chlorides. The symmetrical 
acid chloride with the melting point of 134°, dissolved rapidly 
with the evolution of heat, while warming was neccessary in 
order that the unsymmetrical might react. The products were 
always the same, however, and the discussion of the method 
which follows will apply equally well to either acid chloride. It 
might be remarked that in all the chemical behavior of the two 
acid chorides this seems to be the only case when the high melt- 
ing acid chloride is the more reactive. When the acid chloride 
had dissolved in the pyridine phenol solution the liquid was 
warmed for ten minutes on the water bath. This caused the 
formation of phthaleins, however, and in later preparations the 
warming was omitted, and instead the product simply was al- 
lowed to stand at room tempeVature for the completion of the 
reaction. Alcohol was then added and warmed until all the 
compound was in solution. As the liquid cooled crystals formed 
;as colorless, fiat needles somewhat resembling those of the ethyl 
ihenzoic ester of the sulphone chloride. These contained no chlor- 
ine, however, and were the diphenyl ester. 
A scond crop of crystals which came down showed a canary 
yellow color. The crystal form was that of a blocky rhombo- 
hedron. The yellow color, it has been shown, while very persist- 
ent, is not characteristic, but due to the presence of phthalein 
