A comparative study of radical cations of thiourea,thiosemicarbazide, and diethylthiourea in aqueous sulphuric acid media employing pulse radiolysis technique

The generation of radical cations of thiourea (NH₂)₂C=S], thiosemicarbazide (NH₂―NH)(NH₂)C=S], and diethylthiourea (C₂H₅―NH)₂C=S] in aqueous sulphuric acid media of low to high acid strengths utilizing the pulse radiolysis technique is reported. In this system, the decay half‐life of radical cations of thiourea and its derivatives observed were longer (ranging from 45 to 100 µs at acid strength pH/H₀ = ?4.1), and the formation times could be altered with the change in acid strengths. By doing so, a wide range in half‐life of radical cations of thiosemicarbazide (0.7 to 100 µs) was observed in contrast to thiourea and diethylthiourea with the variation in acid strengths (pH/H₀) from 0.7 to ?4.1. This perhaps helps in studying the spectral and kinetic properties of transient radical cations comfortably. The general mechanism for the formation of radical cations of the aforementioned compounds in radiolysis has been revisited in which the electron transfer reactions are active. Copyright © 2013 John Wiley & Sons, Ltd.