Rexco coal-tar

Figure 2, Off-resonance H-decoupled NMR spectrum of Rexco coal-tar branched chain alkanes in CDCU solution. Quartet 1 (14,0 ppm) arises from methyl, and triplets 2,3,4 (22.8, 28,5, and 29.8 ppm) arise from methylene absorptions of straight-chain sections.

Ti measurements at normal probe temperatiire were made by the inversion-recovery Fourier-transform (IRFT) technique on deuteriated chloroform solutions of pristane (2,6,10,1 i -tetra-methylpentadecane) and of branched-chain/cyclic alkanes from Rexco coal tar and a Turkish asphaltite (Avgamasya). Inversion-recovery traces were recorded by using 200 cycles of the l80°-90°-PD pulse sequence with a pulse delay time (PD) of about 20s at a series of intervals, T (e.g. 1,3,5s, Figure 3). Ti values ( 0.5s) (Table IV) were measiired by plotting In(AQ-A) vs. T, where A is the equilibrium amplitude in a normal FT spectrum and A is the amplitude in an IRFT spectrum (Figure k). 

G.C.-M.S. From the G.C. of the total-alkane fraction of another Turkish asphaltite (Harbulite) (5.), it was possible to recognise three series, namely n-alkanes, acyclic isoprenoids (C15, Cie, Ci8> C12, C2o)> and cyclic isoprenoids (C2 C29, C30, C31 and 032)9 all on the same chromatogram. For the Rexco coal tar,... 

Figure 5, Gas chromatograms of Rexco coal-tar recorded on glass column with eutectic salt on Chromosorb. Key a, total alkanes and b, branched cyclic alkanes following molecular-sieve removal of most of the n-alkanes.

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