The Carbon-13 NMR Spectra of Alkyl Vinyl Ethers, and Their Structures and Reactivities

Abstract

The 13C NMR spectra of alkyl vinyl ethers were investigated at 22.5°C with neat liquid at 15.09 MHz. When the alkyl group of the ether becomes more electron-donating, the chemical shift of the α-carbon of the vinyl group shifts to a higher field, and that of the β-carbon, to a lower field. From these results, it was concluded that the contribution of the resonance form, \barCH2–CH=\overset+O–R, in the ether decreases in the order of the increasing electron-repelling power of the alkyl group. Good correlations were obtained between the chemical shifts of the vinyl group and the reactivity of vinyl ether in the cationic reaction. When the ether becomes more reactive, the chemical shift of the α-carbon shifts to a higher field, and that of the β-carbon to a lower field. This fact clearly shows that the attack of the proton on the β-carbon is not the rate determining step in the cationic reaction of the vinyl group. Linear relations were obtained between the chemical shifts of β-methylene protons and of β-carbon, but no correlation was obtained between the chemical shifts of the α-methine proton and of the α-carbon.

Spontaneous reactions of electron‐accepting substituted quinodimethane with substituted styrenes: Inductive and steric effects on the formation of a zwitterionic intermediate

“…To investigate the inductive effect of p ‐substituted styrenes on this zwitterionic tetramethylene intermediate formation, we measured the chemical shifts (δ, ppm) of the β‐carbon of the vinyl group13, 14 as a measure of the polar effect and then compared them. The β‐carbon chemical shifts of the p ‐substituted styrenes and the terpolymer compositions are summarized in Table 3.…”

Spontaneous polymerization mechanism of electron‐accepting substituted quinodimethane with vinyl ether and cyclic ketene acetal

“…The difference in the electron‐donating property of the comonomers should also affect the reactive intermediate formation. The 13 C chemical shifts of the β‐carbons on vinyl‐type monomers are related to the π‐electron density of the vinyl group,17, 18 and so the chemical shifts can be used as a measure of the electron‐donating property of the monomers. The chemical shifts of β‐carbons of BVE and MDOP measured in chloroform‐ d are 86.1 and 67.3 ppm, respectively; they indicate that MDOP is a stronger electron‐donating monomer than BVE, as expected.…”

Cyclopolymerization XVII. Anionic Cyclopolymerization Tendency of N-Methyldiacrylamide and N-Substituted Dimethacrylamides

“…28 Diamagnetic shileding effect of carbonyl group influences the chemical shifts of ix-protons of ix,/1-conjugated carbonyl compounds together with the electron density at ix-proton. 29 For this reason detailed discussion will not be given based on these results.…”