Some studies in qualitative organic chemistry

The object of this work has been to find suitable qualitative tests for some classes of organic compounds. The reaction must be applicable to 0.5 g. or less, of the compound, and to every member of the series. The resulting derivative must have a good crystalline structure and melting point; must be easily prepared and be stable. .The melting points of such derivatives must differ by at least 5°C. from one member to the next.Substituted hydrocarbons have been oxidised in sealed tubes with nitric acid (sp. gr. 1.2) to the corresponding acids. 0.5 g. substance and 5 c.c. acid were used in each experiment. The yields and melting points of the acids obtained and the peculiarities of each experiment have been noted.Aliphatic amines have been identified by the use of various substituted phenylisothiocyanates. 105. (3- naphthylisothiocyanate has been found to be the most suitable. The amine derivatives have good melting points, crystalline structures, and separate readily from solution. 2:4:5- rinitrotoluene has been used to detect primary aliphatic amines in small quantity but is useless as a general reagent for aliphatic amines.α-phenylindole has been used for the classification of alkyl nitrites, (3- isonitroso-α- phenylindole being formed. The use of this reaction as a qualitative estimation of nitrites has been abandoned, due to a 25% error vh ich could not be detected.Aliphatic monobasic acids have been identified by the formation of 2- substituted benziminazole picrates. The reaction is not quite general, but is exceedingly useful for those acids soluble in water.2:4-Dinitrobenzoic acid has been prepared . from phenylacetic acid and fuming nitric acid. The yield is almost quantitative and the purity good, but as a reagent for alcohols it is inferior to the 3 :5- dinitrobenzoic acid already in use