一般的電化學系統裡，產物是在工作電極上產生，而輔助電極沒有利用到，為了改善這缺點，開發一種新的有機電合成系統，使得陽極及陰極都可以獲得相同的產物，這樣除了可以使能源有效利用外，還可以節省製程設備。右旋阿拉伯糖是五碳糖的一種，是一種維它命B2及維它命D原料的前驅物，它可以經由葡萄糖酸鈉氧化產生，因此本文針對陽極氧化、陰極氧化及陰陽極組對三種方式氧化葡萄糖酸鈉，希望可以開發一種新的高經濟效應的有機電合成製程。

在陽極氧化系統，使用分離式電解槽，針對使用Cl-/OCl-離子為氧化還原媒子之間接電解系統及無氧化還原媒子的系統進行研究。由實驗數據得知在陽極室裡之直接電解陽極氧化系統之電流效率為86﹪，使用Cl-/OCl-媒子之間接電解陽極氧化系統之電流效率為59﹪，可知葡萄糖酸鈉直接在電極表面氧化的系統效果較好。經理論及實驗數據比對分析後得知，葡萄糖酸鈉反應氧化為右旋阿拉伯醣之反應速率決定步驟為如下所示
R1s --> R2s + e- (1)
葡萄糖酸根離子在電極表面失去電子之反應式，而其陽極氧化葡萄糖酸鈉反應之電流速率方程式為
i=((0.89[NaC6H11O7])/(0.7357+[NaC6H11O7]))*exp(0.37Fn2/RT) (2)
其中F 為法拉弟常數，葡萄糖酸根離子形成葡萄糖酸根自由基之過電位。

在陰極氧化系統裡，使用分離式電解槽，針對使用Ce4+/Ce3+，Fe3+/Fe2+，V3+/V2+氧化還原媒子之間接電解系統作探討。氧氣在陰極表面還原為過氧化氫，過氧化氫分解為氫氧自由基，氫氧自由基再氧化葡萄糖酸鈉形成右旋阿拉伯醣。由實驗結果顯示，在陰極室裡，反應物濃度60 mM 葡萄糖酸鈉在25℃ 及1.32 電流密度下，使用 氧化還原媒子較 及 氧化媒子效果好，但是由於自由基反應造成副反應多，因此在陰極氧化生成右旋阿拉伯醣之電流效率不高，約19%。

在陰陽極組對電解系統裡，結合陰極及陽極氧化分別在分離式電解槽及非分離式電解槽進行研究。在非分離式電解槽裡使用Fe2+/Fe3+為氧化還原媒子進行氧化葡萄糖酸鈉產生右旋阿拉伯醣之探討，由實驗結果得知，在氧氣流量為200 ml/min , 0.2N 醋酸及醋酸鈉緩衝溶液，10mM Fe3+離子，25℃及電流密度0.94mA/cm2 操作條件下，陰陽極組對電解系統之總電流效率為75%。
在分離式電解槽裡，實驗結果顯示在陰陽極組對電解系統裡的陰極及陽極反應與單獨使用之陰極及陽極反應結果相同，所以在陰陽極組對電解系統裡，當電荷為68.22C時，可得最大的總電流效率127﹪，陽極最佳的電流效率為86﹪。在陰極室使用 為氧化還原媒子，最佳的電流效率約41﹪。陰陽極組對電解系統在非分離式反應器裡總電流效率為75﹪，分離式反應器之右旋阿拉伯醣生成總電流效率為127﹪，可知分離式電解槽有較佳之電流效率，比單獨陽極氧化或陰極氧化的電流效率高，且比單獨陽極氧化的電流效率高1.5倍，因此使用陰陽極組對電解系統應用於氧化葡萄糖酸鈉生成阿拉伯醣之研究為可行之系統，且可以增加電流效率，節省能源，為一種新穎的產生右旋阿拉伯醣製程。

In a general electrochemical system, the products are produced at working electrode, the counter electrode is not availability. To improve the disadvantage, the electro-organic synthesis process is upgraded when the same product is obtained on both anode and cathode electro-organic synthesis being invented. In this way, the power consumption and cost of equipment are reduced. D-arabinose is a monosacharides, which plays an important role in the synthesis of vitaminB2 and vitaminD. D-arabinose is prepared by degradation oxidation, in which the carbon chain length of sodium gluconate or its derivatives is reduced. Production of D-arabinose via anodic oxidation, cathodic oxidation and paired electro-oxidation were studied in this dissertation. The purpose of this study is to research and development of electro-organic synthesis process which will be less power consumption and high economy.

In anodic oxidative system, using Cl-/OCl- as redox medicator and direct electro-oxidation in divided cell are studied. Effect of operation condition on the reaction rate, reaction kinetics and rate determining step are systematically investigated. The experimental results show that direct electro-oxidation has better than indirect electro-oxidation. The current efficiency are 86% and 59% for direct and indirect electro-oxidation, respectively. The reaction mechanism of sodium gluconate anodic oxidation was proposed. The theoretical analysis correlated with the experimental results well. The rate determining step was found to be the anodic oxidation of gluconate anion to form gluconate free radical.

R1s --> R2s + e- (1)
And the current of the anodic oxidation of sodium gluconate can be expressed as

i=((0.89[NaC6H11O7])/(0.7357+[NaC6H11O7]))*exp(0.37Fn2/RT) (2)

where F is faraday’s constant and is the overpotantial of forming gluconate free radical from gluconate anion.

In cathodic oxidative system, using Ce4+/Ce3+，Fe3+/Fe2+and V3+/V2+ as redox medicators in divided cell are studied. The oxygen is reduced to form hydrogen peroxide at cathode. The OH free radical decomposed form hydrogen peroxide. The OH free radical oxidize sodium gluconate to from D-arabinose. The experimental results indicated that the mediator couple enhanced current efficiency relative to and at 60 mM sodium gluconate, 25℃ with a current density of 1.32 in cathodic chamber. But reaction has many side reactions and the current efficiency of D-arabinose is low, about 19%.

In paired electro-oxidative system, by combining the cathodic and anodic oxidation in both undivided and divided cells are studied. In undivided cell, applying Fe2+/Fe3+as redox mediator for anodic and cathodic paired electro-oxidation of sodium gluconate to D-arabinose, the experimental results show at a 200ml/min oxygen flow rate, 0.2N acetic butter solution contained 10mM Fe3+,25℃, both anodic and cathodic current density are 0.94mA/cm2, the total current efficiency is 75%, in the paired electro-oxidation system.

In divided cell, the experimental results indicate that the current efficiency of anodic/cathodic oxidation in the paired electro-oxidation is the same as that of anodic/cathodic oxidation only. So the maximum total current efficiency for the paired electro-oxidation of sodium gluconate to D-arabinose was 127% with a charge of 68.22 C being passed. The best current efficiency for anodic oxidation was 85% in this system which was found in a single anode as the working electrode. The mediator in the catholyte generates the best current efficiency with the maximum value is 41% in the a cathodic system. The current efficiency for the electro-oxidation of sodium gluconate to D-arabinose in cathodic chamber was unsatisfied. In this study, the highest current efficiency of D-arabinose is 75% in undivided cell and 127% in divided cell. The production of D-arabinsoe via paired electro-oxidation in dived cell is better than in undivided cell. The current efficiency in paired electro-oxidative divided cell’s system is 1.5 times of that of anodic oxidation. Accordingly, the operation in divided cell is better. The paired electro-oxidation of sodium gluconate to form D-arabinsoe is a new process and a potential for commercialization.

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