Ultrasonic and 13C N.M.R. data are reported for l-octanol, 2-octanol, 2,3-dimethyl-3-hexanol and 2,4-dimethyl-3-hexanol. The ultrasonic relaxation data indicate that in 1-and 2-octanol the observed dispersion can be attributed to hydrogen bond exchange processes associated with structural relaxation of the liquid. For 2,3-dimethyl-3-hexanol and 2,4-dimethyl-3-hexanol, an additional contribution associated with internal rotational relaxational processes has been detected. Assignments of the observed 13C spectra are compared with the predictions of the theory developed by Grant and Paul. Activation parameters obtained from the laC and ultrasonic studies are compared with those obtained from the temperature dependence of viscous flow. The conformational changes are discussed in terms of the effects of steric and polar contributions to the internal rotational potential.
Le coefficient de non linéarité B/A a été déterminé dans des mélanges eau-méthanol et eau-éthanol en fonction de la température (de 0 à 50° C) et de la concentration. Les variations de la vitesse du son en fonction de la pression présentent des minima quand on change la concentration. Ces résultats sont reliés aux valeurs calculées pour la pression interne
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