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A laboratory experiment that spectrophotometrically determines the percent of cranberry juice in cranberry-apple juice is described. The experiment involves recording an absorption spectrum of cranberry juice to determine the wavelength of maximum absorption, generating a calibration curve, and measuring the absorbance of cranberry-apple juice. (Contains 3 figures.)

5,6-Dihydro-2H-thiopyran, CH2CH2CH=CHCH2S, has been synthesized and its far-infrared and Raman spectra recorded. Two series of sharp bands were observed originating from 139 and 235 cm-1 in the infrared spectrum for the out-of-plane ring-bending and the ring-twisting vibrations, respectively. A detailed energy level diagram including numerous excited states was determined for the two coupled vibrations. The two-dimensional potential energy surface, which satisfactorily fits more than two dozen observed transitions, was calculated to be V=2.431×104 x41 -0.383×104x21 +2.258×104x42 -1.966×104 x22 +1.026×105x21 x22 , where x1 is the ring-bending coordinate and x2 is the ring-twisting coordinate. The minimum energy on the potential surface corresponds to a twisting angle of 37.8° (the half-chair conformation). The lowest energy bent (boat) conformation corresponds to a saddle point 4130 cm-1 above the twisted conformation on the potential energy surface. The results are compared to analogous molecules and to molecular mechanics calculations. [ABSTRACT FROM AUTHOR]

5,6-Dihydro-4H-thiopyran has been synthesized and its far-infrared spectrum has been recorded. Eleven ring-bending bands originating at 120.7 cm-1 and four ring-twisting bands originating at 274.5 cm-1 were observed. Twelve sum and difference bands in the 383–397 and 148–166 cm-1 regions were also observed and these facilitated the construction of a detailed energy map including numerous excited vibrational states of the two coupled vibrations. The two-dimensional potential energy surface, which satisfactorily fits the observed data, was determined to be V=9.48 ×104x4-4.13×104x2+1.37×104τ4-1.82×104τ2+1.10 ×105x2τ2, where x and τ are the bending and twisting coordinates, respectively. The minima on the potential energy surface correspond to twisting angles of ±48° (half-chair conformation). The lowest energy bent (boat) conformation corresponds to a saddle point 1500 cm-1 above the twisted conformation on the potential energy surfaces, and the barrier to planarity was estimated to be 6000 cm-1. Both of these values have large uncertainties since the vibrational data only extend to 800 cm-1 above the potential surface minimum. The relatively low bending energy and high barrier to planarity can both be explained by the low force constant for the C–S–C angle bending. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The far-infrared spectra arising from the two out-of-plane ring vibrations of 1,3-oxathiolane have been recorded and analyzed. Fifteen pseudorotational (ring-bending) transition frequencies were observed in the 25–125 cm-1 region and were fit with the one-dimensional potential function V(cm-1)=-541(1-cos 2[lowercase_phi_synonym])+139(1-cos 4[lowercase_phi_synonym]). The molecule is twisted with a barrier to pseudorotation of 541±20 cm-1 (1.54±0.06 kcal/mol). The spectra recorded include transition frequencies occurring above the barrier, and this is the first molecule (other than a nearly free pseudorotor) for which such bands have been seen. Seven radial transitions arising from three different pseudorotational states have also been observed in the 297–317 cm-1 region. Those in the pseudorotational ground state can be fit with a one-dimensional double-minimum function with a barrier to planarity of 2720 cm-1. However, this value for the one-dimensional approximation is believed to be too high. Difference bands (180–240 cm-1), sum bands (398–426 cm-1), and double quantum transitions (144–220 cm-1) were also detected and used to confirm the assignments. [ABSTRACT FROM AUTHOR]

2,4,7-Trioxa[3.3.0]octane (247TOO) is an unusual bicyclic molecule which can exist in four different conformational forms which are determined by the directions of the two ring- puckering motions. The vibrational assignments of 247TOO have been made based on its infrared and Raman spectra and theoretical density functional theory (DFT) calculations. The two ring-puckering motions (in-phase and out-of-phase) were observed in the Raman spectra of the liquid at 249 and 205 cm(-1) and these values correspond well to the DFT values of 247 and 198 cm(-1). Ab initio calculations were utilized to calculate the structures and conformational energies for the four energy minima and the barriers to interconversion and the data was utilized to generate a two-dimensional potential energy surface (PES) for the two ring-puckering motions. The resulting quantum state energies for this PES were then calculated in order to better understand the patterns that are produced when the PES has four energy minima at different energy values. The wave functions corresponding to the different quantum states were also calculated. The NMR spectrum of 247TOO showed the presence of the two lowest energy conformations, consistent with the results of the ab initio calculations.