生命的起源與天門冬氨酸在水中的結晶; The Origin of Life and the Crystallization of Aspartic Acid in Water

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題名:	生命的起源與天門冬氨酸在水中的結晶;The Origin of Life and the Crystallization of Aspartic Acid in Water
作者:	林育琨;Yu-Kun Lin
貢獻者:	化學工程與材料工程研究所
關鍵詞:	生命的起源與天門冬氨酸;The Origin of Life and Aspartic Acid
日期:	2010-06-30
上傳時間:	2010-12-08 13:35:37 (UTC+8)
出版者:	國立中央大學
摘要:	消旋性化合物的種類有三種: 外消旋混和物 (racemic conglomerate)、外消旋化合物(racemic compound) 或者擬消旋體 (pseudoracemate)。利用初步溶劑篩選程序來篩選左旋(l)、右旋(d)、和消旋(dl)的天門冬氨酸 (aspartic acid)，包含溶解度 (solubility)、同質異相表 (form space)、溶解度相圖 (phase solubility diagram) 以及晶貌 (crystal habits) 的資料建立成工程資料庫，結果發現左旋、右旋、及消旋的天門冬氨酸均易溶於水。而這些資料可以用來決定最適當的結晶過程來分離對掌異構物。另一方面，發現天門冬氨酸的左右旋分子在水中有不同的相態。我們利用冰點和結晶動力學證明溶液中有不同的相態。而液相中外消旋混合物溶液(conglomerate solution)受到溫度和時間因素能轉變成外消旋化合物溶液 (racemic compound solution)。而外消旋混合物和外消旋化合物溶液分別結晶出外消旋混合物和外消旋化合物兩種不同的晶體。當溶液溫度為45度及放置時間為5小時，外消旋混合物溶液最後會轉變成外消旋化合物溶液。儘管如此，將琥珀酸溶解在外消旋混合物溶液，能使介穩態的外消旋混合物溶液在60℃下穩定達8個小時，而不會轉變成外消旋化合物溶液。同樣地，酸鹼中和法和反溶劑降溫法可藉由加入琥珀酸，使得外消旋化合物分離成外消旋混合物。而其中左旋天門冬氨酸也可以當做分離左右旋的晶種。因此，在原始地球上很容易產生大規模分離天門冬氨酸對掌性分子的現象。最後,我們使用導電度計監控天門冬酸在水與丙酮共溶劑中整個介晶質結晶過程，以證明其外消旋混合物溶液和外消旋化合物溶液的差異，和探討加入左旋天門冬氨酸晶種於外消旋化合物溶液的結晶行為，並且整合熱力學與動力學的資訊來建立基本結晶動力學參數。 Racemic species involve racemic conglomerate, racemic compound, or pseudoracemate. Engineering technology data included solubility, form space, phase solubility diagram, and crystal habits of d-, l-, and dl-aspartic acid were collected by initial solvent-screening. The d-, l-, and dl-aspartic acid were all soluble in water. The study determined the crystallization of enantiomers. The existence of different types of enantiomeric solution phase of aspartic acid in water was discovered. We used freezing point of the solution, and crystallization kinetics to prove that those solution phase were different. The transformation of a conglomerate solution (CS) to a racemic compound solution (RCS) was dependent on both temperature and time. The CS was the solution phase which produced conglomerate crystals, and the RCS was the solution phase which gave a racemic compound. The solution phase transformation of the CS of aspartic acid to the RCS of aspartic acid took 5 h at 45oC to complete. However, the presence of succinic acid dissolved in the aqueous solution of what at 60oC hindered the transformation of the CS of aspartic acid to the RCS of aspartic acid up to 8 h. The succinic acid could stablize the metastable conglomerate generated in water by rapid acid-base reactions and the addition of an antisolvent crystallion with the temperature drop of racemic solution of aspartic acid. The presence of l-aspartic acid seeds could alter the crystallization pathways to produce conglomerate aspartic acid solids. Therefore, crystallization of enantiomers of aspartic acid by preferential crystallization could have been very common and easy to be carried out in a large scale on the primitive earth. Finally, we used the electrical conductance (1) to prove the existence of different types of molecular interactions in the CS and the RCS of aspartic acid, (2) to study the effects of the seeds of l-aspartic acid in the aqueous solution of racemic aspartic acid, and (3) to monitor the overall kinetics of crystallization from the acetone-water solution. The fundamental kinetic (nucleation and crystal growth) and thermodynamic (Gibbs free energy) parameters were then estimated.
顯示於類別:	[化學工程與材料工程研究所] 博碩士論文

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