OKLAHOMA ACADEMY OF SCIENCE 55 



BEHAVIOR OF SOME CLOSELY RELATED COM- 

 POUNDS WHEN MELTED TOGETLIER 



L. Chas. Raiford, 1917. 

 (Abstract) 



It is a well known fact that the freezing point of a pure solvent 

 is lowered by the presence of a non-volatile solute. This fact is 

 utilized commercially in the preparation of low melting alloys for 

 different uses, and in many other ways. In organic chemistry the 

 depression of the melting point of a pure compound by admixture 

 with foreign matter is a common behavior familiar to every worker. 

 The depression is shown not on-y by mixtures of compounds that 

 are difi'trcnt in composition and molecular structure, but even by 

 such closely related sribstances as stereoisomers, and the question 

 of the identiiy of tv/o organic products is usually most easily de- 

 cided by melting them together. On the other hand, failure to de- 

 press each other's melting point is practically always held to prove 

 the identity of the products. 



In a study of the action of halogen on 4-nitro-m-cresol, it 

 was found by Raiford* that 2, 6-dichloro-4-amino-m-cresol, m. p. 

 *Jour. Am. Chem. Soc, 36, 670 (1914). 



175°, could be melted with 2, 6-dibromo-4-amino-m-cersoI. m. p. 

 175°, with but a very slight depression (168-171°), far less than r'^ 

 usual'y observed in such cases. The structures of the two com- 

 pounds show that they differ only in the replacement of chlorine by 

 bromine. (Illustrations which cannot be printed were inserted at 

 this point.) 



This behavior m.ade it a matter of interest to examine other 

 compounds of similar structure, with the hope of learning if the 

 pair cited was exceptional in this respect. Since that time four 

 other pairs of substances have been examined, with the result that 

 the depressions were in each case less than one degree, which would 

 be negligible in the work of the average organic chemist. Such be- 

 havior would render it impossible to decide with certainty between 

 two products without recourse to an analysis, and in the last case 

 even this would not suffice, because the compounds are structural 

 isomers. (Illustrations which cannot be printed were also inserted 

 at this point,, showing the compounds and their melting points.) 



The last pair of products examined though they were obtained 

 from a single compound, were not identical ; they turned out to be 

 structural isomers. They were carefully differentiated from each 

 other by oxidation into their respective chlorimids, quinones, the 



