Biphenyls dissolving metals

The dissolving metal reduction of benzo[b]furans and dibenzofurans is a classical technique and, depending on the conditions, can give rise to a variety of products.Several examples are summarized in equations (104-108). " The cleavage of dibenzofurans to afford 2-hydroxy biphenyls (equation 107) is a particularly valuable route to these compounds. The reduction of 3-carbomethoxybenzofu-rans with Mg/MeOH (equation 108) is reminiscent of the indole reduction reported earlier (equation 51). 

Recently, Commodor Solutions Technology Inc. (88,89) and Pittman and co-workers (90-93), have pioneered the ambient temperature, solvated-electron reduction of PCBs, both neat and in wet soils, using Ca/NHs and Na/NHs. Remediation of PCB- and chlorinated aliphatic hydrocarbon-contaminated soils, wet and dry by solvated electron reductions at ambient temperatures, are addressed by Pittman et al in chapter 25. Dechlorination rates using Na/NHs are huge (diffusion controlled) and the chlorine is mineralized as NaCl. High dechlorination efficiencies are available at reasonable consumptions of sodium metal. In this technique, wet soils were slurried in liquid NH3 and then either calcium or sodium metal was dissolved. The solvated electrons dechlorinated PCBs to biphenyl at far faster rates than the solvated electrons were consumed by water. While this method is promising for environmental remediation, it requires a suitable reaction vessel able to sustain the moderate pressures produced by ammonia at temperatures between 0 and 50°C. Ammonia boils at -33 °C, but its use as a liquid in the 0 to 50 °C range is standard practice in industry. 

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