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Abbruzzetti S, Sottini S, Viappiani C, et al. Kinetics of proton release after flash photolysis of 1-(2-nitrophenyl)ethyl sulfate (caged sulfate) in aqueous solution. J Am Chem Soc. 2005;127(27):9865-74doi: 10.1021/ja051702x.
Abbruzzetti, S., Sottini, S., Viappiani, C., & Corrie, J. E. (2005). Kinetics of proton release after flash photolysis of 1-(2-nitrophenyl)ethyl sulfate (caged sulfate) in aqueous solution. Journal of the American Chemical Society, 127(27), 9865-74. https://doi.org/10.1021/ja051702x
Abbruzzetti, Stefania, et al. "Kinetics of proton release after flash photolysis of 1-(2-nitrophenyl)ethyl sulfate (caged sulfate) in aqueous solution." Journal of the American Chemical Society vol. 127,27 (2005): 9865-74. doi: https://doi.org/10.1021/ja051702x
Abbruzzetti S, Sottini S, Viappiani C, Corrie JE. Kinetics of proton release after flash photolysis of 1-(2-nitrophenyl)ethyl sulfate (caged sulfate) in aqueous solution. J Am Chem Soc. 2005 Jul 13;127(27):9865-74. doi: 10.1021/ja051702x. PMID: 15998092.
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J Am Chem Soc. 2005 Jul 13;127(27):9865-74. doi: 10.1021/ja051702x.

Kinetics of proton release after flash photolysis of 1-(2-nitrophenyl)ethyl sulfate (caged sulfate) in aqueous solution.

Journal of the American Chemical Society

Stefania Abbruzzetti, Silvia Sottini, Cristiano Viappiani, John E T Corrie

Affiliations

  1. Dipartimento di Fisica, Università degli Studi di Parma, Parco Area delle Scienze, 7A, 43100 Parma, Italy.

PMID: 15998092 DOI: 10.1021/ja051702x

Abstract

The kinetics of proton release after laser photolysis of 1-(2-nitrophenyl)ethyl sulfate (caged sulfate) have been characterized by time-resolved absorbance and photoacoustic methods. The absorbance at approximately 400 nm is observed to rise with a biphasic behavior in which a prompt component (formation of the nitronic acid) is followed by a slower (tau approximately 63 +/- 6 ns) phase (deprotonation of the nitronic acid). The decay of this intermediate occurs with a lifetime which is affected by the pH of the solution and the laser pulse energy. In buffered aqueous solution at pH 7, 20 degrees C the aci-nitro decay rate is 18 +/- 4 s(-1). Protons are released to the solution with rate (1.58 +/- 0.09) x 10(7) s(-1) at neutral pH from the nitronic acid intermediate. From the numerical analysis of the protonation kinetics of suitable pH indicators, we could estimate the pK(a) of the nitronic acid as 3.69 +/- 0.05. At acidic pH, a substantial fraction of the aci-nitro intermediate is in the protonated form and this leads to a biphasic release of protons, with the slower phase being characterized by an apparent rate constant strongly dependent on the pH. The strongly acidic character of the final photoproduct (sulfate ion) means that there is negligible buffering of photoreleased protons.

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