No abstract

539.196:535.375 Self-association of y-butyrolactone molecules in pure liquid state and in nonpolar solutions is studied by spontaneous Raman spectroscopy. The constant and the enthalpy of formation of cyclic diraers in liquid ~,-butyrolactone are calculated.Earlier, we studied intermolecular interactions of molecules with different symmetries, dipole moments, and functional groups in dipolar aprotic solvents by Raman spectroscopy [1][2][3][4][5]. In this work, which is a continuation of previous studies, we examine y-butyrolactone. EXPERIMENTALThe Raman spectra were recorded on a DFS-24 spectrometer with a temperature accessory maintzlning the temperature in the range of 290-340 K within 0.2 K. A 488 nm argon laser line with a power of 1 W served as a source of excitation. Standard 90* angle sample irradiation (as in the case of recording the Iw and 11,7-/ spectra) was used.Carbon tetrachloride was employed as a nonpolar solvent. The samples were thoroughly purified and dried according to standard procedures. The degree of drying was monitored by the IR absorption bands of the stretching vibrations of water molecules.The spectra were processed on a personal computer; complex contours were decomposed into components, and spectral parameters were determined excluding instrument distortions [6]. The error of concentration determination of molecules in different associates found from the scatter of experimental values was not greater than 5% in all cases, and the accuracy of determination of band maximum positions was ___1 cm -1. C-O): DISCUSSION OF RESULTS?-Butyrolactone is an ester containing a five-membered heterocycle with two functional groups (C = O and O~_Ck~CH2Our previous studies of serf-association of y-butyrolactone by IR absorption spectroscopy showed that the v(C = O) 1760 cm -1 and v(C-O) 1168 cm -1 bands in the spectrum of y-butyrolactone undergo the greatest changes when this compound is dissolved in carbon tetracMoride [7]. As the extent of dilution increases, the half-width of the v(C-O) vibration decreases by 11 cm -1, reaching its maximal value of 17 cm -1 at a concentration of 0.1 M, and the maximum Ufa State Aircraft Technical University.

No abstract

No abstract

No abstract