RESTRICTED INTERNAL ROTATION IN ETHYL ALCOHOL
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Date
1952
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Ohio State University
Abstract
The infrared spectra of vapor $C_{2}H_{5}OH$ and $C_{2}H_{5}OD$ and liquid $C_{2}H_{5}OD$ have been measured in the rock salt and lithium fluoride regions. On the basis of these spectra an assignment of the fundamental vibrations of ethyl alcohol has been made. While some doubt as to the frequencies of some of the vibrations still exists, the assignment appears satisfactory for a statistical thermodynamic calculation. The barriers to internal rotation of the $CH_{3}$ and OH groups are determined by comparing the calculated and observed thermodynamic data. New vapor heat capacity measurements are reported. It is shown that gas imperfection corrections can be made by use of the Clapeyron equation and that the observed heat capacities and entropies can then be corrected to the ideal gas state. With a $CH_{3}$ group barrier of 3000 cal., the three fold barrier hindering rotation of the OH group is fixed between 0 and 1200 cal. Most satisfactory agreement is obtained with barriers of 3300 and 800 cal. for the $CH_{3}$ and OH groups respectively.
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Author Institution: Department of Chemistry, Northwestern University