B.— chf;mistry. 43 



anthracene, although a small proportion of this hydrocarbon itself may 

 possibly be present. Oxidation of various fractions from this product leads 

 to 2-methylanthraquinonc, 2 : 6- and 2 : 7-dimcthylanthraquinones and 

 2:3: 6-trimethylanthraquinone. The proof of the orientation of methyl 

 groups in these anthracene derivatives has involved the synthesis of the 

 hydrocarbons and of their quinones [Journ. Chem. Soc, 1929, 2203 and 2551). 



Bases. — The volatile bases of low temperature tar are mainly tertiary 

 amines although a small amount of aniline was detected. The following, 

 bases were isolated and purified through their crystalline mercurichlorides : 

 pyridine, a-picoline, 2 : 4- and 2 : 6-lutidines and symmetrical collidine ; 

 quinoline and quinaldiue were isolated as picrates. 



Phenols. — Low temperature tars contain a high proportion of material 

 extractable with aqueous caustic soda, but only a portion of this soluble 

 extract consists of true phenols, the remainder is composed of non-phenolic 

 substances which, however, dissolve in solutions of the alkaline phenolates. 

 These non-phenolic materials are recovered from a caustic soda extract 

 of the tar either by agitation with an organic solvent such as chloroform, 

 or more simply by saturating the alkaline extract with salt. The true 

 phenols remaining in the alkaline solution are separated into crystalline 

 and resinous portions by solution of the former in light petroleum. 

 Further fractionation of the petroleum soluble phenols has led to the 

 isolation of the following compounds : phenol, the three cresols and five 

 of the six possible xylenols. Bacteriological examination of the phenols 

 of low temperature tar has shown that their germicidal value increases 

 with rise of boiling point to an optimum fraction boiling at 140-170° under 

 5 mm. pressure. Moreover, it has been found that direct chlorination of 

 these higher phenols of low temperature tar increases considerably their 

 germicidal potency.- 



The Resinoids op Tar. 



With each class of crystalloid in the low temperature tar there is 

 present a corresponding resinoid, which constitutes the least volatile 

 portion of each major fraction. These products, which are termed 

 respectively resinenes (neutral resins), resinamines (basic resins), resinols 

 (phenolic resins) and resinoic acids (acidic resins), are obtained as 

 amorphous powders after extraction of the corresponding crystalloids 

 with petroleum or other suitable solvent. These resinous tar products 

 are promising materials for further research from both scientific and 

 industrial view points. 



An extension of the solvent method of extraction to other varieties of 

 tar from wood, peat, lignite and bituminous coal has revealed the presence 

 in each tar of the four classes of resins, although in wood tars the amount 

 of resinamines was very small. Coal tars produced by carbonisation 

 at high and at intermediate temperatures show considerable variations in 

 their resin contents. 



Aqueous Liquors of Coal Carbonisation. 



The aqueous liquors which accompany low temperature tars have been 



extracted systematically with organic solvents in quantities of 30 gallons 



at a time, and in this way phenol, o-cresol, catechol and its two mcthvl 



derivatives resorcinol and quinol, have been isolated, together with a 



