Aromatic Ring Structure in Solvent Extracts of Binder Pitches

Abstract

In order to investigate ring structure of polycondensed aromatic hydrocarbons in binder pitches, solvent extracts of the pitches were analyzed by using a square wave polarography. Pitches used were five kinds, that is, straight coal-tar pitch, reformed coal-tar pitches and naphtha-tar pitch. Their pitches were fractionated by benzene and N, N-dimethylformamide (N, N-DMF). The reduction wave of the fractions (bezene soluble matter, and N, N-DMF soluble but benzene insoluble matter) were gained in N, N-DMF solution at the potential between 0 V and -2.35V vs Hg pool. Qualitative identification of reduction wave was carried out refering to the reduction potential of standard aromatic hydrocarbons.Results obtained were as follows, 1) All of polarograms for the benzene soluble matter showed the peak pattern having several reduction waves. Components in the straight and the reformed coal-tarpitches had aromatic ring structures such as shown in Table 3. But the reduction wave for the ring structure of anthracene, which may be included in coal-tra pitches, could not be detected. Naphtha-tar pitch consisted of aromatic ring structure such as tetracene, fluoranthene, pyrene and acenaphthene. The content of these components, however, was smaller than those in coal-tar pitches.2) For the N, N-DMF soluble but benzene insoluble matter, the polarograms showed the pattern having two reduction waves at about 0.5V and about-1.5V, and a broad line from about-0.5V to-1.5V. For this fraction, therefor, it is consi-dered that the identification of aromatic ring structure by using a square wave polaro-graphy is rather difficult.