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Issue 17, 1996
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Preparation and crystallinity of a large unsubstituted crown ether, cyclic heptacosa(oxyethylene)(cyclo-E27, 81-crown-27), studied by Raman spectroscopy, X-ray scattering and differential scanning calorimetry

Abstract

Cyclic heptacosa(oxyethyelene)(cyclo-E27, 81-crown-27) was prepared from linear α-hydro, ω-hydroxy-heptacosa(oxyethylene) by reaction with tosyl chloride under alkaline conditions, purified by preparative-scale gel permeation chromatography, and studied by laser-Raman spectroscopy, wide-angle and small-angle X-ray scattering, and differential scanning calorimetry. Comparison was made with the properties of linear oligo(oxyethylene) dimethyl ethers (including C1E27C1). The sub-cell of the crystalline cyclic oligomer was the same as that of its linear counterparts, i.e. the same as that of high-molar-mass poly(oxyethylene). However, the cyclic oligomer crystallised as a twice-folded ring, as confirmed by its long spacing and the frequency of its single-node longitudinal acoustic mode (LAM-1). Enthalpies of fusion and melting temperatures were analysed to provide estimates of the enthalpy and entropy of formation of a fold in an oligo(oxyethylene) layer crystal.

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Article type: Paper
DOI: 10.1039/FT9969203173
Citation: J. Chem. Soc., Faraday Trans., 1996,92, 3173-3182
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    Preparation and crystallinity of a large unsubstituted crown ether, cyclic heptacosa(oxyethylene)(cyclo-E27, 81-crown-27), studied by Raman spectroscopy, X-ray scattering and differential scanning calorimetry

    Z. Yang, G. Yu, J. Cooke, Z. Ali-Adib, K. Viras, H. Matsuura, A. J. Ryan and C. Booth, J. Chem. Soc., Faraday Trans., 1996, 92, 3173
    DOI: 10.1039/FT9969203173

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