Chemical Constants and Absolute Entropy by Rodebush W. H.

By Rodebush W. H.

Show description

Read or Download Chemical Constants and Absolute Entropy PDF

Similar chemistry books

The Chemistry of Essential Oils and Artificial Perfumes - Volume 2 (Fourth Edition)

Quantity 2 (of the 2 quantity set): part titles are . .. (1) the basic Oil and Its scent . .. (2) ingredients of crucial Oils, man made Perfumes and remoted Aromatics . .. (3) The research of crucial Oils.

Group 13 Chemistry I: Fundamental New Developments

Over the past decade our view of chemistry has developed considerably. while person researchers formerly considering particular parts of chemistry, comparable to inorganic, natural, and so forth. we now take a extra holistic procedure. powerful and effective learn initiatives now contain no matter what features of the chemistry subdisciplines which are had to entire the meant paintings.

Extra info for Chemical Constants and Absolute Entropy

Example text

Hence, according to Scheme I, when the rate-determining step is no longer the formation of the intermediary ozone-olefin adduct but its conversion into primary ozonide, the overall process is nucleophilic in nature provided that the final step is the ring-closure involving O". [This interpretation offers a justification for Cvetanovic's hypothesis ( I I ) that k << k. 0 la* Figure 7. Verification of Equation 12 for cis-1,2-disubstituted ethylenes Conversely, the results obtained for the monosubstituted ethylenes can be interpreted in terms of a reduced complex formation under the influence of electron-withdrawing groups, resulting in a relatively smaller contribution of pathway 2 and in a lowering of the rate constant.

233). re re The dependence of the relative reaction rates on olefin geometry can be discussed with reference to Equation 14. As pointed out b y Murray and co-workers (25), the complex formation occurs with cis-olefins rather than with their trans isomers for steric reasons; hence, K (cis) > K (trans). However, during the formation of the primary ozonide b y either path the olefinic carbon atoms change i n hybridization, from sp to sp . The bond angles thus decrease from 1 2 0 ° to 1 0 9 ° ; i n the cis isomers, this results i n a compression of the substituents van der Waals radii.

Both, therefore, have the trans configuration. It is remarkable that the trans ozonide i n this case is the only product, even when pure cis-l,4-dibromo-2,3-dimethyl-but-2-ene is ozonized. The configurations of the other ozonides are based on the assumption that the trans isomers have the lower dipole moments i n comparison with the cis compounds. As a measure of the dipole moment the retention time i n liquid phase or gas chromatography was used. The isomer with the lower retention time should be the trans compound.

Download PDF sample

Rated 4.78 of 5 – based on 38 votes