Visual titrations in nonaqueous solvents with benzanthrone as internal indicator

Abstract

A systematic study of the acid-base reactions in polar as well as nonpolar sdvents with benzanthrone as an internal indicator has been made. In phosphorus oxychloride, sulfuryl chloride, and thionyl chloride, solutions of pyridine, quinoline, stannic chloride, titanium tetrachloride have been used as titrants to indicate the reversible behavior of benzanthrone. In the case of arsenic trichloride, only the results given by basic titrants are subject to quantitative interpretation because the end point with acidic titrants cannot be detected with precision. However, the behavior of benzanthrone in carbon tetrachloride and chlorobenzene is not reversible nor does it provide a means of quantitative assessment of acids and bases. Nevertheless, this difference in the mode of action of benzanthrone in polar and nonpolar solvents helps in understanding the fundamental distinction between the two types of solvents.