Pulse Radiolysis of Pyrrolidine

The formation, decay, and absorption spectra of transients formed from pyrrolidine in aqueous solutions were studied. The solvated electron (${\rm e}_{{\rm aq}}^{-}$) reacts with the protonated and the nonprotonated pyrrolidine forming the${\rm C}_{4}{\rm H}_{8}{\rm N}$· radical. The rate constants are:$k({\rm e}_{{\rm aq}}^{-}+{\rm C}_{4}{\rm H}_{8}{\rm NH}_{2}{}^{+})=(7.5\pm 1.5)\times 10^{6}\ M^{-1}\ \text{second}^{-1}$ and$k({\rm e}_{{\rm aq}}^{-}+{\rm C}_{4}{\rm H}_{8}{\rm NH})=(1.1\pm 0.5)\times 10^{6}\ M^{-1}\ \text{second}^{-1}$. The${\rm C}_{4}{\rm H}_{8}{\rm N}$· radical has an absorption maximum at 3200 Å,$\epsilon =510\ M^{-1}\ {\rm cm}^{-1}$, and disappears in a second-order reaction,$k=3.1\times 10^{9}\ M^{-1}\ \text{second}^{-1}$. The rate constants for the reaction of aqueous pyrrolidine with OH radicals,$k=9.6\times 10^{9}\ M^{-1}\ \text{second}^{-1}$ for pH 2 and$k=1.45\times 10^{10}\ M^{-1}\ \text{second}^{-1}$ for pH 8, were also determined. The pyrrolidine transients formed by these reactions have$\epsilon =290\ M^{-1}\ {\rm cm}^{-1}$ at 3200 Å and decay by a first-order reaction,$k=3.1\times 10^{4}\ {\rm sec}^{-1}$ (half-life 15 μsecond). For the explanation of the results a probable reaction mechanism is proposed.