Order-disorder phase transitions in solid cyclopentene, cyclohexene, tetramethylene sulfoxide, pentamethylene sulfide, cycloheptane, cycloheptene, 1,3-cycloheptadiene and 1,3,5-cycloheptatriene, were studied by various combinations of differential scanning calorimetry, proton spin-lattice relaxation time measurements, and variable temperature infrared and Raman spectroscopy. / Possible unit cell symmetries have been proposed for the low temperature phases of several of these compounds, based on splitting observed in the vibrational spectra. The high temperature phases of cyclopentene, cyclohexene and 1,3-cycloheptadiene, for which the flexibility of the ring is reduced relative to the saturated analogues due to the presence of one or more double bonds, were found to be characterized by anisotropic molecular reorientation, as opposed to the other compounds, in which isotropic reorientation occurred. The ring puckering vibrations, when observed, were found to undergo significant frequency shifts at the order-disorder transitions. "Glassy crystals" were readily formed from cyclohexene, cycloheptane, cycloheptene, and 1,3-cycloheptadiene, the spectra of which confirmed the presence of static disorder related to the disorder present in their respective high temperature phases. / Phase transitions in cyclohexane and cyclohexane-d$ sb{12}$ at high pressure were investigated by infrared and Raman spectroscopy using diamond anvil cells. Two phase transitions were observed in cyclohexane at 5.1 and 9.6 kbar, respectively. The vibrational spectra indicated that the change in unit cell symmetry was from O$ sb{ rm h}$ to D$ sb{ rm 2h}$ at the first transition, and then to C$ sb{ rm 2h}$ at the second transition. A study of the C-H oscillators of cyclohexane-d$ sb{11}$, dilute in cyclohexane-d$ sb{12}$, confirmed these changes in unit cell symmetry.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.74305 |
| Date | January 1989 |
| Creators | Haines, Julian |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001067411, proquestno: AAINN63565, Theses scanned by UMI/ProQuest. |
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