利用雷射瞬間光解儀器可以觀察到由4-Chromanol及1-(2-Methoxyphenyl)ethanol 會生成相對應的不穩定反應中間體碳陽離子，因為起始物不同，產生的碳陽離子穩定度也不一樣，生命週期大約為6~8μs。而所生成的碳陽離子再與添加的親核劑(胺類)進行SN1反應形成產物，在這之中我們利用動力學實驗來探討這兩個碳陽離子與親核劑的二級反應速率常數，因為碳陽離子穩定度不同，所以反應性、選擇性也不一樣，依據這個研究成果可以證明反應性、選擇性原理，反應性愈高其選擇性愈差，反之亦然。另外，同時也利用各種不同的Bunting的N+值來比較，呈現正相關性。

The reactive intermediate carbocations of 4-Chromanol and 1-(2Methoxyphenyl)- ethanol have been determined using laser-flash photolysis techniques. Life-time of carbocations depends on the stability is about 6~8 s. While, carbocation reacts with amine, the nucleophile, by SN1 reaction to generate the products. The second-order rate constants of the reaction of this two carbocations and nuceophiles are determined by studying kinetics of laser-flash photolytically. Because the stabilities of carbocation are different, the reactivities and the selectivities would not be same. Furthermore, using the Bunting’s nucleophilicity parameter to compare with the result also prove the Reactivity Selectivity Principle.

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