The Bromine-Sensitized Decomposition of Chlorine Monoxide in Green Light

Abstract

Chlorine monoxide undergoes a bromine-sensitized decomposition in light of wave-length 5460 A. The reaction involves short chains and is accompanied by an appreciable dark reaction. The quantum yield is 4.3 at 19 °C. A decrease in pressure occurring near the end of the reaction has been shown to be a photochemical effect, and it is due probably to the bromine-sensitized decomposition of chlorine dioxide formed during the combined light and dark reactions.A mechanism similar to that described by Finkelnburg, Schumacher and Stieger for the unsensitized reaction appears to account for most of the observations.

The chemistry of chlorine monoxide (dichlorine monoxide)

“…The photodecomposition of Cl20 at 564 nm has been found to be sensitized by bromine, with a quantum yield of 4.3 at 19 °C. 110 The process involves short chains and is accompanied by an appreciable dark reaction. The similar quantum yields, virtually equal within experimental error, of the sensitized and unsensitized reactions suggest that energy exchange between Br2 and Cl20 is very specific and takes place at nearly every collision.…”

“…At low temperatures (60-100 °C), the reaction is slow, reaching completion in 12 to 24 h. Above 100 °C, the rate increases so that at 150 °C, the reaction is complete within a few minutes.117"121 At temperatures below 130 °C, the rate of decomposition of Cl20 is proportional to its concentration,117•118 while at 140 °C the rate is proportional to [Cl20]°75.118 All reactions above 110 °C were found to end with an explosion. 118 To account for all of these observations, two different mechanisms have been proposed.…”

Photoreactions Sensitized by the Halogens.

“…Chlorine monoxide undergoes a bromine-sensitized decomposition using light of wave length 5460 A. (7). The reaction involves short chains and some chlorine dioxide is formed.…”