以FTIR探討2,2-二甲基-3-乙基-3-戊醇與3-乙基-2-甲基-3-戊醇兩種具有立體障礙醇類的氫鍵自結合現象

Abstract

本篇論文的主要目的，在於利用傅立業轉換紅外線光譜儀，來偵測一些具有立體障礙醇類的自結合現象。利用醇類在稀薄溶液中OH基的吸收光譜，可以分別求出單體與雙體的面積。這些光譜中單雙體面積重疊的部分，則利用高斯—勞倫茲混合分佈校正曲線予以分離。再根據濃度變化的數據，依照我們新推導出的兩個公式，分別求出單體吸收係數、雙體吸收係數以及平衡常數。最後再根據平衡常數隨溫度變化的關係，利用van't Hoff理論作圖，可以求得各個系統的標準結合熵(□Ho)和標準結合焓(□So)。 研究主要分為兩個系統。第一個系統為探討2,2-二甲基-3-乙基-3-戊醇溶解於四氯化碳、二硫化碳、四氯乙烯、正辛烷等溶劑中的氫鍵自結合現象。第二個系統則為探討3-乙基-2-甲基-3-戊醇溶解於四氯化碳、二硫化碳、四氯乙烯、正辛烷等溶劑中的氫鍵自結合現象。我們可由這些探討更加瞭解氫鍵的性質。

The monomer-dimer self-association of some alcohols with bulky side chains has been studied using FTIR spectroscopy. The spectral band of the OH fundamental stretching for a monomer and that for a dimer were resolved and their respective integrated absorbances were calculated. The dilution shift data of OH proton were measured and employed to determine the molar absorptivity of the monomer band, the dimer band and the dimerization constant. The standard enthalpy and entropy of dimerization were determined via a van't Hoff plot from the temperature variation of the dimerization constant. This study includes two systems. The first deals with the self- association of 2,2-dimethyl-3-ethyl-3-propanol through hydrogen bonding in carbon tetrachloride, carbon disulfide, tetrachloroethylene and n-octane. The second deals with the self-association of 3-ethyl-2- methyl-3-propanol through hydrogen bonding in carbon tetrachloride, carbon disulfide, tetrachloroethylene and n-octane. We can understand the character of hydrogen bonding through this discussion.