Details

Autor(en) / Beteiligte

• Knesel, George Albert

Titel

1. Correlations of Electronic Effects of Substituents with NMR Spectra. 2. Addition Reactions of Cis, Trans-1,5-Cyclodecadiene and Cis-Cyclodecene and Trans-Cyclodecene

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

1966

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Part 1: Correlation of Electronic Effects of Substituents With N.M.R. SpectraSeveral series of compounds in dimethyl sulfoxide solutions have been studies by nuclear magnetic resonance spectroscopy. The data show definite correlations with electronic effects. In the first series, the substituted phenols, the chemical shifts for the phenolic protons were found to be strongly dependent on the electronic nature of the substituent and are linearly correlated to Hammett sigma constants. A few sigma constants are not well correlated by the chemical shifts. This non-correlation is attributed to various solvent effects peculiar to dimethyl sulfoxide. This method presents a convenient way of determining sigma constants for new substituents. In a similar study on a series of substituted benzaldehydes, there is general correlation between chemical shifts of the aldehydic protons and electronic effects of the substituents. No quantitative correlation exists, however, with sigma constants. The n.m.r. spectra of a series of substituted alcohols in dimethyl sulfoxide showed loss of the multiplicity which had been obtained with unsubstituted alcohols. This difference is attributed to the higher acidities of the hydroxyl protons due to the electro-negative character of the substituents .Part 2: Addition Reactions of cis,trans-1,5-Cyclodecadiene and cis- and trans-CyclodeceneAdditions of various reagents to cis,trans-1,5-cyclo-decadiene and cis- and trans-cyclodecene have been studied. Those reactions which give normal 1,2-addition products (epoxidation, methylenation, hydroboration, diimide reduction, and catalytic hydrogenation) show a high selectivity for the trans double bond. This high selectivity is attributed to the relative freedom of the transition state from steric factors when the trans rather than the cis double bond is attacked.Three reactions (bromination, ozonization, and acetoxylation) have been found to give products formed by transannular reactions: hydrogen migration across the ring in the case of the cyclodecenes and electron shift in the case of cis, trans-1,5-cyclodecadiene. these reactions, bromination, has been studied extensively. In the case of cis,trans-1, 5-cyclodecadiene study of models shows that the stereochemistry of the product is dependent on the conformation of the ethylenic pi clouds when the reagent makes its initial attack. Analysis of the reaction products does not reveal selectivity of initial attack at the trans double bond by bromine or lead tetraacetate.