The vapor phase infrared spectra of cyclohexene and 2,3hyphen;dihydropyran, 50ndash;700 cmminus;1

摘要

The infrared spectrum from 50 to 700 cmminus;1of cyclohexene in the vapor phase is reported and analyzed for the first time in terms of a number of very weak sequences resulting from combinations of various fundamentals with the outhyphen;ofhyphen;plane skeletal bending and twisting modes. The spectrum of 2,3hyphen;dihydropyran is reinvestigated with the view of finding corresponding combination sequences not previously reported. By means of an approximate method the barriers to planarity and interconversion are estimated to be, respectively, 5826 and 2571 cmminus;1for cyclohexene, and 5371 and 3310 cmminus;1for 2,3hyphen;dihydropyran.