臺灣博碩士論文加值系統

摘要
為了更深入地研究鐵電性液晶分子所含掌性末端基中第二個掌性中心對液晶物性的影響，本論文從消旋的2-乙基己酸經光學分割、還原反應和碘化反應製得(S)-1-碘-2-乙基己烷（5），在Ag2O的作用下它和(S)-乳酸乙酯經由醚化反應連結成掌性有機酸乙酯6，再經皂化反應就得到具有兩個不對稱中心的新穎有機酸7（2(S)-[2(S)-乙基己氧基]丙酸）。
經由酯化反應，掌性有機酸7與含環的酚化合物1A可以鍵結成新穎的鐵電性液晶8A，其液晶相順序為K─SC＊─SA─I，掌性層列C相溫度為62℃-29℃，自發極化值為50 nC/㎝2（52℃）；而掌性有機酸7與含聯苯環的酚化合物1B則可鍵結成另一個新穎的鐵電性液晶8B，其液晶相順序為K1─K2─ SC＊─N＊─I，掌性層列C相溫度為106℃-62℃，自發極化值為120 nC/㎝2（96℃）。
將其結果與先前的研究結果[12，14]比較，我們發現：（1）核心分子的結構對於液晶分子的液晶相順序、掌性層列C相的溫度範圍和自發極化值的大小有絕對的影響。（2）第二個掌性中心的立體障礙會影響液晶分子的構形，使得自發極化值有明顯的變化，而這和已知文獻[16]認為其變化應不明顯的推論有很大的不同。

Abstract
A new chiral organic acid 7, 2(S)-[2(S)-ethylhexoxyl] propionic acid was synthesized and used as a chiral moiety for the preparation of ferroelectric liquid crystals. The chiral starting material, (S)-1-iodo-2-ethylhexane（5）, was synthesized from racemic 2-ethylhexanoic acid by optical resolution, reduction and iodination. The new chiral propionic ester 6 was prepared by the etherification of nature ethyl lactate with 5 in the presence of Ag2O. After saponification of 6 the new chiral propionic acid 7 was formed.
The new ferroelectric liquid crystal 8A was synthesized by the esterification of the new chiral organic acid 7 and the phenolic derivative containing naphthalene ring 1A. The liquid crystal phase sequence of the compound 8A is K─SC＊─SA─I. Its temperature range of SC＊ phase is from 62℃ to 29℃ and its Ps value is 50 nC/㎝2 at 52℃. The other new ferroelectric liquid crystal 8B was synthesized by the esterification of the new chiral organic acid 7 and the phenolic derivative containing biphenyl ring 1B. The liquid crystal phase sequence of compound 8B is K1─K2─ SC＊─N＊─I. Its temperature range of SC＊ phase is from 106℃ to 62℃ and its Ps value is 120 nC/㎝2 at 96℃.
Comparing these results with the prior research results[12，14], two key points of the work are worth noticing:
（1）The liquid crystal phase sequence, the temperature
range of SC＊ phase, and the spontaneous polarization are
sensitive to the core structure.
（2）The stereochemistry of the second chiral center could
affect the conformation of liquid crystal compounds and
therefore their spontaneous polarization. There is an
obvious difference between their Ps values. Such a
difference is not expected from the previous results[16].

目錄
中文摘要………………………………………………………………....i
英文摘要………………………………………………………………...ii
目錄………………………………………………………………...…...iii
圖目錄…………………………………………………………………...v
表目錄…………………………………………………………………..vi
第一章液晶簡介...………………………………………………......1
第一節 液晶的發現………………………………………………..1
第二節 熱向型液晶………………………………………………..2
第三節 液晶相分類………………………………………………..4
第二章鐵電性液晶……………………………………………………..9
第一節鐵電性液晶歷史..………………………………………….9
第二節鐵電性液晶之物性……………………………………….11
第三節鐵電性液晶之分子設計與結構探討……………………13
第四節文獻回顧…………………………………………………15
第三章研究動機………………………………………………………25
第四章實驗部份………………………………………………………30
第一節藥品……………………………………………………….30
第二節儀器……………………………………………………….32
第三節合成途徑………………………………………………….34
第四節實驗方法………………………………………………….38
第五章結果與討論……………………………………………………52
第一節合成部份…………...……………………………………..52
第二節結構鑑定………………………………………………….61
第三節液晶相探討……………………………………………….67
第四節綜合討論………………………………………………….69
第六章結論……………………………………………………………74
第七章參考文獻………………………………………………………76
第八章附錄……………………………………………………………79

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