Some Unimolecular Fission Reactions Decomposition into Stable Molecules

Some Unimolecular Fission Reactions Decomposition into Stable Molecules 

First-order unimolecular fission reactions in which the products are stable molecules have been compiled in Table XI.4. As can be seen, the frequency factors all fall in the range between 3 X 10 to about 10 sec with most of them very close to the value of 10 sec b 

The two groups of reactions with low frequency factors, namely, the decompositions of the acetals and the decompositions of the chloroformate esters, would both have to go through the formation of four-membered-ring transition complexes, although the acetals can also decompose via a six-membered ring. While it might be expected that the formation of a 

Calvin and 11. W. Alter, J. Chem. Phys., 19, 768 (1952), have attempted to investigate cis-trans isomerizations in the liquid phase. They found experimental difficulties in side reactions, and while they could represent their data by means of first-order plots, they did not investigate any catalytic effects of the presemte of free radicals. Their frequency factors fell in the range 10 sec to 10 sec , for wliich they found no reasonable explanation. 

TabI/B XI.4. Unimol,ec0i,ab Gas-phase Decompositions That Give Stable Molecules 

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