Chloroprene autoxidation

Initiated Oxidation. The initial rates of oxidation of chloroprene, initiated with 2,2 -azobisisobutyronitrile, were measured in the range 20° to 40°C. at a total pressure of 700 mm. of Hg. The difficulty with these measurements was that chloroprene autoxidizes so readily that even when the initiator is used at the fairly massive concentration of 0.462M, the rate of oxidation is constant for only a few minutes before acceleration, resulting from a contribution to initiation from chloroprene peroxide. 

Chloroprene monomer will autoxidise very rapidly with air, and even at 0°C it produces an unstable peroxide (a mixed 1,2- and 1,4-addition copolymer with oxygen), which effectively will catalyse exothermic polymerisation of the monomer. The kinetics of autoxidation have been studied [1], It forms popcorn polymer at a greater rate than does butadiene [2],... 

Autoxidation of Chloroprene. The oxidation was autocatalytic and up to about 5 mole % oxidation—i.e., 5 moles of oxygen absorbed per 100 moles of chloroprene initially present—the quantity (mole % oxidation)172 was a linear function of time, as observed by Kern (10). Beyond this extent the oxidation continued at a rather greater rate than given by this relation and was still accelerating at 25 mole % oxidation. Values of K in the expression... 

In the early stages of the autoxidation of chloroprene the amount of oxygen absorbed increased as the square of the time. This dependence on time is frequently observed in autoxidations and is an approximation to that expected for an oxidation of long chain length, initiated by the first-order decomposition of the peroxidic product and terminated by a bimolecular reaction of the propagating peroxy radicals. 

If the autoxidation of chloroprene is initiated by the first-order decomposition of the polyperoxide, P, the rate equation will be of the form... 

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