利用雷射瞬間光解儀器觀察2-3-Dyhydro-benzofuran-3-ol生成相對應的不穩定反應中間體碳陽離子。在先前的研究裡，使用不同的親核劑(胺類)進行SN1反應，探討4-chromanol與1-(2-Methoxyphenyl)ethanol之間的關係，可以得到4-chromanol的碳陽離子反應速率比1-(2-Methoxyphenyl)ethanol的碳陽離子快。所以在此研究觀察2-3-Dyhydro-benzofuran-3-ol生成的碳陽離子對比上面兩個化合物，探討二級反應速率常數。因為碳陽離子穩定度不同，所以得到的反應性、選擇性也不同。這一個研究可以證明反應性、選擇性原理。當反應性越高，選擇性就會越差，反之亦然。此外也利用各種不同Bunting的N+值來證明有無相關性。

The reactive intermediate of 2-3-Dyhydro-benzofuran-3-ol have been determined by using laser-flash photolysis techniques. Life-time of the carbocation depends on the stability. In past research, we discuss the relation between4-chromanol and 1-(2-Methoxyphenyl)ethanol by adding different amine to produce SN1 reaction, then we found out the second-order rate constant of chroman-4-ylium is faster than 1-(2-Methoxyphenyl)ethan-1- ylium. In this research, we compare second-order rate constant of 2-3-Dyhydro-benzofuran-3- ylium with two carbocations that we discussed, the reactivity and the selectivity would be the same in that the stability of the carbocations are different, consequently using the Bunting’s nucleophilicity parameter with the result we did prove the Reactivity Selectivity Principle.

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