Enthalpimetry of Olefins in the Nanomolar Region

Abstract

Listen

Translate article

One of the strongest features of direct injection enthalpimetry, developed by Jordan, Ewing, Wasi lewski and others (1–3) is that, while there is nothing theoretically impossible about a reaction with a zero enthalpy change, experience tells us that they are very rare. Thus almost all reactions can, in principle/be used as the basis for a direct enthalpimetric determination of any of the reactants. In practice, we place more severe limitations on the reactions we choose; normally we require them to be fast, to go to completion, be fairly specific and to have a rather large heat of reaction so that the enthalpimetric method will have sensitivity great enough to be competitive with other methods. Hydrogenation represents a good compromise among these several characteristics we seek as it is specific for nonaromatic unsaturation under the conditions we describe and the reaction goes to completion in virtually every case studied. Further, it is exothermic to the extent of about 30 kcal/mole, quite a high value in comparison to almost any other reaction except combustion which is not used because it is almost totally nonspecific.