Reaction between methane and mixtures of bromine and chlorine first fractions (25 %) isolated, hexanejtoluene (loll) as eluent, consisted of acephenanthrene, m.p. 1100 (from methanol) (lit. '' 106"); m/e 204; UV h,,, (log E) (methanol) Abstract. As in the previously reported low-and high-temperature photochemical reactions, preferred formation of CH,Br is observed when a gas mixture of the title reactants is exposed to the action of a "cold" electrical discharge (35°C) or to high temperatures (100-450°C). The influence of the main reaction variables on product composition is discussed. It is suggested that the mechanism of CH,Br-formation in the discharge reaction is largely analogous to that operative in the thermal and the photochemical processes. A crucial step in these reactions is the primary attack of a chlorine atom on methane. The different continous-flow processes have approximately been optimized with respect to their CH,Br yield per pass (discharge reaction: 16%; thermal reaction: 62 %). In addition, optimum energy yields with respect to CH,Br formation are compared. Of the four methods tested the hightemperature photochemical reaction displays the most favorable combination of CH,Br yield and energy yield. The discharge method generally combines a high selectivity and energy yield with low conversions per pass, and may be attractive ifrecycling of reactants is possible.