Lower alkyl biphenyls

The widespread use of biphenyl and methyl-substituted biphenyls as dye carriers in the textile industry has given rise to significant environmental concern because of the amount released to the environment in wastewater effluent. Although biphenyl and simple alkyl-biphenyls are themselves biodegradable, the prospect of their conversion by chlorination to PCBs in the course of wastewater treatment has been a subject of environmental focus. Despite the fact that the lower chlorinated biphenyls are also fairly biodegradable continued environmental concern has resulted in decreased use of biphenyl as a dye carrier. 

Vinylchlorosilanes undergo Friedel-Crafts alkylation with aromatic compounds in the presence of Lewis acids to give 2-(chlorosilyl)ethylarenes [Eq. (17)].lb 32,33 The reactivity of vinylchlorosilanes for the alkylation of aromatic compounds is slightly lower than that of allylchlorosilanes.lb 3,32 The reactivity of vinylsilanes for alkylation depends on the substituents on the silicon of the vinylsilane. The reactivity of vinylchlorosilanes decreases in the following order dichloro(methyl)vinyl-silane > trichlorovinylsilane > chloro(dimethyl)vinylsilane. The alkylation of mono-substituted benzenes such as toluene, chlorobenzene, and biphenyl with di-chloro(methyl)vinylsilane (lc) at 75-80 °C for 2h affords alkylated products in 50-63% yields.32... 

Biphenyl and its derivatives are present in coal-derived liquids such as tars from coal carbonization and pyrolysis, although at concentrations lower than those of naphthalene derivatives. Shape-selective alkylation of biphenyl can produce 4,4 -dialkyl substituted biphenyl (4,4-DAB), the starting materii for monomer of some LCP materials represented by Xydar (Scheme 1). Partially dealuminated proton-form mordenite can be used as shape-selective catalyst for isopropylation of biphenyl to obtain 4,4-diisopropylbiphenyl (4,4 -DIPB), as illustrated in Scheme 7. 

Fig. 2. Larmor frequency and angular dependences of the longitudinal proton spin relaxation time Tj for the two /i-alkyl-cyano-biphenyls 5CB and 8CB, respectively, at temperatures in the middle of the nematic mesophases. The upper diagram shows the dispersion profiles Ti(v) with the director H a igned parallel (A = 0) and perpendicular (A = 90 ) to the external 2 eman field, Bq, and suggests to distinguish at least four relaxation regimes. The lower diagram shows ri(A) in different frequency ranges of the dispersion profile. The solid lines are model fits of equation (3a) to the experimental 5CB data points as discussed in the text.

Fig. 7. Arrhenius plots of diffusion constants of nematic and isotropic pentyl-alkyl-cyano-biphenyl SCB (upper) and pentyl-alkyloxy-cyano-biphenyl 50CB (lower) to illustrate the quality of the Arrhenius law, the anisotropy ratio and the changes due to the slightly different side-groups of the two cyano-biphenyls. The data cannot be interpreted with existing theories. ...

Flexibilizers are added in orda to provide molding materials which are lower in elasticity, greata toughness and flexibility s.ss.se) There are unreactive and reactive type flexilali%i5 for epoxy resins 57.87-92) -j-ijg forma- contain phthalic acid esta or chlorinated biphenyl. As for the latta, there are many kinds mono-epoxides or phenols of which have long alkyl chains, long-chained diamines, dimer acids, and trimer... 

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