Heterocyclic 3,5-disubstituted phenylpyrazoles and isoxazoles: Synthesis and mesomorphic behavior

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/100545

Title:	Heterocyclic 3,5-disubstituted phenylpyrazoles and isoxazoles: Synthesis and mesomorphic behavior
Authors:	賴重光;Kuo, Hsiu-Ming;Tsai, Shao-Ling;Lee, Gene-Hsiang;Sheu, Hwo-Shuenn;Lai, Chung K.
Contributors:	理學院化學學系
Keywords:	chemical reactions;chemical structure;Crystallization;Derivatives;Ethanol;Ethyl alcohol;hydrogen;Mesophase;Methylhydrazine;Phases;Pyrazole;pyrazoles;temperature;X-radiation
Date:	2013-01-14
Issue Date:	2026-04-21 14:06:06 (UTC+8)
Publisher:	Elsevier Ltd.;Elsevier Ltd
Abstract:	摘要： Three new series of heterocyclic pyrazoles Mpz-Cn and Epz-Cn and isoxazoles Iz-Cn were prepared, characterized, and their mesomorphic properties investigated. These heterocyclic derivatives were obtained by condensation–cyclization of β-diketones with methylhydrazine, 2-hydradinoethanol or hydroxylamine in refluxing THF/ethanol. One single crystallographic structure of nonmesogenic Epz-C4 was determined by X-ray analysis. It crystallizes in a triclinic space group P−1. An H-bond-induced structure was formed, giving a better aspect ratio required for the formation of mesophases. Both series of pyrazoles Mpz-Cn and EpZ-Cn exhibited monotropic smectic A phases, in contrast, isoxazoles Iz-Cn formed enantiotropic smectic C phases. A lack of H-bond due to a removal of hydrogen atom from pyrazolyl rings (–NH) significantly lowered the clearing temperatures of both Mpz-Cn and EpZ-Cn. These compounds have good thermal stabilities. [Display omitted] 出版者： Elsevier Ltd 出版日期： 2013-01-14 出處： Tetrahedron, 2013-01, Vol.69 (2), p.618-626 版權： 2012 Elsevier Ltd 識別號： ISSN: 0040-4020 識別號： EISSN: 1464-5416 識別號： DOI: 10.1016/j.tet.2012.11.013
Appears in Collections:	[Department of Chemistry] journal & Dissertation

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