以離子溶液催化醇與酸酐的之酯化反應
在酯化反應中,經由實驗結果,我們發現離子液體對於此反應有催化的效果。離子液體 是在室溫下呈現液態的離子化合物,將醇類與酸酐放入離子液體中有助於酯化反應的進行, 基於這個新的發現,我們開始尋找使用不同種類的離子液體做實驗,選出適當的離子液體, 並且測試離子液體在不同環境下的催化效果,以及適合的使用計量;更進一步,我們找出離 子液體在催化反應之後,將離子液體回收的方法:利用有機溶劑將離子液體和產物分層並萃 取出產物,把離子液體回收再利用,符合現代推動綠色化學的趨勢。接下來我們探討離子液 體對催化反應的擴展性與應用,先由不同結構的一級醇反應到醯胺鍵的生成,最後推展到合 成阿斯匹靈,實驗結果說明,用離子液體做催化劑,也可以成功的合成阿斯匹靈。 We have established for the first time that ionic liquids, which possess the property of Lewis acid, can facilitate acylation of alcohols with anhydrides to form esters with photo-excitation. With the initial finding, we then screen through different types of ionic liquids with varying counter anions, loading, and external light or heat sources to sort out the best reaction conditions. To gain insights into the working mechanism, the dynamic profile of the catalytic reaction was monitored by analyzing the reaction mixture by using ‘H NMR spectroscopy. The ionic liquids can be recovered by extractive separation from the acylation product, which meets the major theme of green chemistry. To extend the substrate scope and applications of the new catalytic process, different functional primary alcohols and amines were further examined. More importantly, we have utilized the new catalytic protocol for the acetylating of salicylic acid, leading to aspirin with high efficiency.
磁場中的離子轉速-探討離子遷移速度變因
帶電的離子受到垂直的磁場與電場作用,會因為受到洛倫茲力而產生有趣的轉動現象。我們利用上述原理設計簡易的裝置設備,探討電解質溶液不同濃度、不同離子電荷數,受到不同離子間靜電力,產生不同的離子移動速度。經由所測量的時間與圓周運動的距離,可計算電解質的絕對遷移速度。由實驗結果推論在固定電場下,當電解質濃度降低,正、負離子間的相互作用力降低,離子遷移速度(migration velocity)加快,莫耳電導率 Λ(mole conductance)也隨之增加。同濃度時,電解質2-1 價型硝酸銅與2-2 型硫酸銅離子強度(ionic strength)不同,2-2型硫酸銅離子強度較大,遷移速度較小,莫耳電導率Λ 也較小。Because of the effect of Lorentz force, charged ion will have interesting rotation under the vertical magnetic and electric field. We use the above principle to design a simple instrument or tool, in order to evaluate and study the formation of different ionic mirgration velocities. The velocity of the charged ion in the instrument is affected by differences in the electrolyte, the charge differences of the ion tested and the differences in electrostatic forces between ions. From the experiment we can deduct that at a fixed constant electric field, when the concentration of the electrolyte is reduced, the interaction of forces between positive and negative ions will be reduced. When the migration velocity of ions increase, the mole conductivity Λ (mole conductance ) will also increase. At the same concentration, the ionic strength between copper nitrate ( 2-1valency type ) and copper sulfate ( 2-2 valency type ) are not identical. Copper sulfate, a 2-2 valency type has higher ionic strength, the velocity is slower and the mole conductivity Λ is also smaller.
線鋁之情-以陽極氧化鋁模板製作氧化亞銅奈米線
我們使用陽極氧化鋁(AAO)模板來製備銅及其氧化物的奈米線。以硫酸銅和乳酸配製電鍍液,利用氫氧化鈉水溶液(NaOH)將其pH 值調整到12,供以不同電壓,可電鍍出銅及氧化亞銅奈米線。在較高電壓下可製備出銅奈米線,而在較低電壓下可製成氧化亞銅奈米線,若使用中間電壓則能製得銅及氧化亞銅的混合態。利用x 光繞射分析儀(XRD)來分析其結晶構造、使用場發射掃描式電子顯微鏡(SEM)以得知其表面形貌。電鍍出的奈米線直徑約60 nm。奈米線的長度可藉由調整電鍍時間或電壓來控制。在製作IC 內部導線方面,銅奈米線深具開發潛能;在提升太陽能電池的轉換效率、製作可見光光觸媒方面,氧化亞銅奈米線極具前瞻性。We electrodeposited copper and cuprous oxide (Cu2O) nanowires with anodic aluminum oxide (AAO) templates. Both Cu and Cu2O nanowires could be prepared with an alkaline cupric lactate solution, which was adjusted to pH 12 using a 6 M NaOH, when supplied with different electrolytic voltages. Cu nanowires could be prepared when a higher voltage was supplied, and Cu2O nanowires could be prepared with a lower voltage. A mixture of Cu and Cu2O nanowires could be prepared with a supply of a voltage in between. X-ray diffraction (XRD) is used to determine the phase composition, and scanning electron microscopy (SEM) is employed to characterize the morphology of the nanowires. The length of nanowires can be controlled by adjusting the time spent on electrodeposition and the voltage supplied. The resultant diameter of the nanowires was about 60 nm. Cu nanowires are promising materials for making the conductive wires in IC, and Cu2O nanowires hold great promise for improving the conversion efficiency of solar cells and manufacturing visible-light photocatalyst.
Vitamin C in Cold and Flu Drinks
This chemistry project was designed to measure the vitamin C levels within liquid cold and flu remedies, and see if they had been accurately stated on the package. A range of Cold and flu drinks was selected, including one made with only cold water (Lemsip Original, Lemsip Max, Effer-C-Cold Water, Relief and Lemting) .The procedure used to carry out the experiment was a redox titration, each trial required two titrations, with the first being a blank titration to determine a sodium thiosulfate concentration in the absence of vitamin C. The following Drinks had more Vitamin C than stated on the packaging – Lemsip Original (19.4%), Lemsip Max (22.1%), Effer-C (17%) and Relief (8.8%). Lemting was the only drink made to directions that had less Vitamin C than stated by 31.8%. Two conclusions can be drawn from these results, the first being that Lemting has the most inaccurately recorded mass of vitamin C and is also the only drink with less vitamin C than stated. The other interesting result is that Effer-C (the only drink made with cold water) had 170mg of extra vitamin C. Of the other drinks that had more vitamin C, Lemsip Max was next with an extra 22.8mg. Early research had showed that Vitamin C was affected by high temperatures (above approximately 70oC) and, as cold and flu drinks are commonly made with hot water the Vitamin C levels might change when they were made up. This poses a further possible research question which is, in making cold and flu remedies with hot water is some of the available Vitamin C being destroyed?
Asymmetric Total Synthesis of GlaxoSmithKline’s Potent Phosphodiesterase PDE IVb Inhibitor
Phosphodiestarase of subtype PDE IVb inhibitors are considered as perspective drugs for the treatment of the central nervous system disorders (depression, Alzheimer’s disease, Parkinson’s disease). Pyrrolizidinone Glaxo-1, proposed by GlaxoSmithKline, is a highly potent PDE IVb inhibitor (IC50 = 63 nM), then conventional phosphodiesterase inhibitors Ro-20-1724, Rolipram and Cilomilast. However the activity of the Glaxo-1 was studied on a racemic sample, since the asymmetric approach to its synthesis has not been developed. Therefore the purpose of this research was the development of an efficient synthetic scheme enabling enantioselective excess to both (-)- and (+)-Glaxo-1, which can be than subjected to biological studies. \r The key stage in proposed asymmetric synthesis (-)- and (+)-Glaxo-1 is stereoselective [4+2]-cycloaddition of the nitroolefin to an optically activity vinyl ethers, derived from (-)- or (+)-trans-2-phenylcyclohexanols. The resulting chiral cyclic nitronates are transformed into a functionalized cyclic oxime ethers using tandem sylilation-nucleophilic substitution procedure. Reduction and decarboxylation of these products lead to optically pure Glaxo-1 and the regeneration of chiral 2-phenylcyclohexanols (91%). \r Thus both enantiomers (+) and (-)-Glaxo-1 were obtained selectively in average yield 12% from isovaniline and nitroethane. The study of biological profiles of each enantiomer of Glaxo-1 will be conducted in near future.