Kinetic Studies of the Thermal Iodine-Catalyzed Isomerization of Cis-and Trans-Dichlorethylene in Several Solvents

Citation

Wood, Reuben Esselstyn (1939) Kinetic Studies of the Thermal Iodine-Catalyzed Isomerization of Cis-and Trans-Dichlorethylene in Several Solvents. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/jpj1-4818. https://resolver.caltech.edu/CaltechTHESIS:05222024-214213318

Abstract

An investigation of the thermal iodine-catalyzed isomerization of cis- and trans-dichlorethylene was carried out. The reaction cisC₂H₂Cl₂ and → transC₂H₂Cl₂ its reverse were studied in solutions in dichlorethylene, benzene, and cyclohexane, at different temperatures, and with different concentrations of iodine and dichlorethylene.

The following differential rate expression is in accord with the kinetic data for all the solutions studied:

d(C)/dt = [k K(T) + (C)]

in which equation k is a rate constant depending on iodine concentration

K is the equilibrium constant (cisC₂H₂Cl₂/transC₂H₂Cl₂

C and T are respectively cis- and trans-dichlorethylene

the concentrations are expressed in mol fractions

In 10 mol percent solutions of C₂H₂Cl₂ in benzene, over the temperature range studied (140° to 160° for k, 150° and 185° for K)

k/√(I2) = 1.30 x 10¹⁵ e-15650/T K = .617 e580/T

when the time is expressed in hours.

In the other solvents the values of the numerical constants in these expressions were only slightly changed.

The mechanism following is proposed as probable for the reaction:

I₂ ⇄ 2I I + C ⇄ CI

CI ⇄ TI TI ⇄ T + I

For the estimation of the composition of the solutions containing the two dichlorethylene isomers a dielectric-constant measuring apparatus was built. With this apparatus curves relating dielectric constant to composition were obtained for several liquid systems.

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