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https://hdl.handle.net/2440/4501
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Type: | Journal article |
Title: | Gas phase and condensed phase SNi reactions. The competitive five and six centre cyclisations of the 4,5-epoxypentoxide anion. A joint experimental and theoretical study |
Author: | Hevko, J. Dua, S. Taylor, M. Bowie, J. |
Citation: | International Journal of Mass Spectrometry, 1999; 185/186/187:327-341 |
Publisher: | ELSEVIER |
Issue Date: | 1999 |
ISSN: | 1387-3806 1873-2798 |
Abstract: | Ab initio calculations [at the MP2 Fc/6-31+G(d) level of theory] indicate that the barriers to the transition states for the competitive five and six centre SNi cyclisation processes of the 4,5-epoxypentoxide anion are both 48 kJ mol-1. Experimental studies show that (1) in solution, the 4,5-epoxypentoxide anion cyclises (and at the same time opens the ethylene oxide ring) to give tetrahydrofurfuryl alcohol [tetrahydro-2-furanmethanol (the product of the five-centre cyclisation)] as the predominant product on workup, and (2) collision activation of the 4,5-epoxypentoxide anion in the gas phase gives the tetrahydro-2-furanmethoxide anion as the exclusive product. Since the computed barriers for the cyclisations proceeding through five- and six-membered transition states are comparable, frequency factors (Arrhenius A factors) must be controlling the courses of the kinetically controlled reactions. A comparison of the calculated harmonic vibrational partition functions for the two transition states confirms a higher value of A (and hence a higher rate) for the reaction proceeding via the five-membered transition state. |
DOI: | 10.1016/S1387-3806(98)14098-8 |
Published version: | http://dx.doi.org/10.1016/s1387-3806(98)14098-8 |
Appears in Collections: | Aurora harvest 2 Chemistry publications |
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