Intramolecular Thermal Motions in Liquid n-Propanol (+ Glycerol), A Proton Magnetic Relaxation Study. 2

Article abstract of DOI:10.1021/j100084a043

The proton magnetic relaxation times T₁ and T₂ of the four n-propanol species HOC3D7, DOCH2CD2CD3, DOCD2CH2CD3, and DOCD2CD2CH3 have been measured at the resonance frequency ν = 12 MHz as a function of the temperature in the range 80 < T/K < 330.T₁ measurements were performed at a second frequency, ν = 48 MHz, as well.Further measurements of the same general kind were done on the mixtures n-propanol + 50 mol percent glycerol (glycerol-d₅ and -d₈) and n-propanol + 70 mol percent glycerol (glycerol-d₅ and -d₈).Isotopic dilution measurements with constant content of propanol and varying degree of deuteration were made to obtain the intramolecular relaxation rates.The proton NMR spectra of the four propanol species were recorded at T = 130 K.From all these data correlation times for the various proton-proton vectors were derived.It turned out that to each motion a slow and a fast mode contribution exists, however, the results are not compatible with the model of a molecule as a system of rigid bodies connected by axes about which rotation occurs.A formal description and interpretation is given involving the molecule concept without the presupposition of a microscopic rigid body.