Urea dewaxing of middle fractions of Morgan (UAR) petroleum

4-Bromobiphenyl; an ordered crystal with a structure similar to that of biphenyl

“…At the other end of the scale are a number of biphenyl derivatives which, like unsubstituted C~2H~0 (Hargreaves & Rizvi, 1962), crystallize with the molecules located at centers of symmetry. Members of this group include 4,4'-difluoro- (Halstead, Spiess & Haeberlen, 1976) and 4,4'-dihydroxybiphenyl (Farag & Kader, 1960) and the linear polyphenyls p-terphenyl (Baudour, Delugeard & CaiUeau, 1976) and pquaterphenyl (Baudour, Delugeard & Rivet, 1978). Although the center of symmetry implies molecular planarity, the molecules in these crystals are almost certainly disordered and the inter-ring angles are not well determined.…”