66178-22-1Relevant academic research and scientific papers
Relative Thermodynamic Stabilities of Isomeric Alkyl Allyl and Alkyl (Z)-Propenyl Ethers
Taskinen, Esko
, p. 11389 - 11394 (2007/10/02)
The relative thermodynamic stabilities of ten allyl ethers (ROCH2CH=CH2) and the corresponding isomeric (Z)-propenyl ethers (where R is an alkyl group, or a methoxysubstituted alkyl group) have been determined by chemical equilibration in DMSO solution with t-BuOK as catalyst.From the variation of the equilibrium constant with temperature, the values of the thermodynamic parameters ΔG, ΔH and ΔS of isomerization at 298.15 K were evaluated.The propenyl ethers are highly favored at equilibrium, the values of both ΔG and ΔH for the allyl -> propenyl reaction being ca. -18 to 25 kJ mol-1.The favor of the propenyl ethers is increased by bulky alkyl substituents, and decreased by methoxysubstituted alkyl groups.In most cases the entropy contribution is negligible; however, for R=(MeO)2CH and R=(MeO)3C the values of ΔS are ca. -5 J K-1 mol1-.
Simple Enols. 3. Stereochemistry of Simple Enols in Solution
Capon, Brian,Siddhanta, Arup K.
, p. 255 - 257 (2007/10/02)
The simple enols vinyl alcohol, (E)-prop-1-en-1-ol, (Z)-prop-1-en-1-ol, and 2-methylprop-1-en-1-ol have been generated from reactive precursors in solution in slightly aqueous CD3COCD3 and their 1H NMR spectra measured under conditions where exchange of the OH proton is slow on the NMR time scale.At -80 deg C J(OH-CαH) for vinyl alcohol and (E)-prop-1-en-1-ol is greater than 9 Hz whereas that for (Z)-prop-1-en-1-ol and 2-methylprop-1-en-1-ol is less than 6 Hz.With the former two compounds J(OH-CαH) decreases with temperature whereas with the latter it increases.It is concluded that the former two enols exist mainly in the s-cis-co nformation and the latter mainly in the s-trans conformation.The 13C NMR spectra of these enols in aqueous CD3COCD3 were also measured, and it is concluded that some factor other than a through-space shielding effect is important in determining the relative chemical shifts of the olefinic carbon atoms.
