Destruction of halogenated hydrocarbons with solvated electrons in the presence of water

Model halogenated aromatic and aliphatic hydrocarbons and halogenated pheno ls were dehalogenated in seconds by solvated electrons generated from sodiu m in both anhydrous liquid ammonia and ammonia/water solutions. The minimum sodium required to completely dehalogenate these model compounds was deter mined by increasing the Na/substrate ratio until halogen loss was complete. Minimum sodium consumptions were determined in both anhydrous liquid ammon ia and with a (5, 20, 50-fold molar excess of water per mole of halide). Wh ile more Na was consumed in the presence of water, these dehalogenations we re still efficient when a 50-fold water excess was present. Dehalogenation is faster than competiting reactions with water. CCl4 and CH3CCl3 in the pr esence of a stoichiometric deficiency of sodium produced only CH4 and CH3CH 3 and recovered CCl4 or CH3CCl3, respectively. No partially dechlorinated p roducts were detected, indicating dechlorination was diffusion controlled. Na consumption per chlorine removed (as NaCl) was lower than that of Li, K or Ca and this advantage increased in the presence of water. Na consumption was lower using Na chunks instead of a thin Na mirror. Chloroaromatic comp ounds gave the parent aromatic hydrocarbon and aminated products in anhydro us ammonia but aminated products did not form when water was present. (C) 2 000 Elsevier Science Ltd. All rights reserved.