NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY. ABNORMAL SPLITTING OF ETHYL GROUPS DUE TO MOLECULAR ASYMMETRY. II
CALIFORNIA INST OF TECH PASADENA GATES AND CRELLIN LABS OF CHEMISTRY
Pagination or Media Count:
Studies of the nuclear magnetic resonance of ethyl groups are being conducted. The spectra of acetaldehyde diethyl acetal I and diethyl sulfite II are discussed as examples of magnetic nonequivalence of the methylene hydrogens in R-CH2-O-XR1R2R3, where R is equal to CH3 and X is equal to S, C, P, etc. Complete agreement between the computed 40 mc and observed 40 mc spectra of II in benzene was achieved only with the coupling of constants of opposite signs. This dif erence in sign between the geminal and vicinal H-H couplings runs directly counter to the theoretical predictions of Karplus and Gutowsky J. Chem. Phys. 311278, 1959 and Karplus J. Chem. Phys., 3011, 1959. Different sets of spin-coupling and chemical-shift parameters were found to give nearly identical theoretical spectra for II in benzene and each of these corresponds well to the experimental spectrum at 60 mc.