Abstract
The oxidation of N-acetylthiourea (ACTU) by acidic bromate has been studied by observing formation of bromine in excess bromate conditions. The reaction displays an induction period before formation of bromine. The stoichiometry of the reaction was determined to be 4:3: 4BrO 3 – +3(CH 3 CO)NH(NH 2 )C=S+3H 2 O®4Br – +3(CH 3 CO)NH(NH 2 )C=O+3SO 4 2– +6H + (A) with a complete desulfurization of ACTU to its urea analogue. In excess bromate conditions the stoichiometry was 8:5: 8BrO 3 – + 5(CH 3 CO)NH(NH 2 )C=S + H 2 O ® 4Br 2 + 5(CH 3 CO)NH(NH 2 )C=O + 5SO 4 2+ + 2H + (B). Bromine is derived from an extraneous reaction in which bromide fromstoichiometry (A) reacts with excess acidic bromate. The oxidation of ACTU by aqueous bromine gave stoichiometry (C): 4Br 2 (aq)+(CH 3 CO)NH(NH 2 )C=S+5H 2 O®8Br – +CH 3 CO)NH(NH 2 )C=O+SO 4 2– + 10 H + .Reaction (C) is much faster than reactions (A) and (B), with a lower limit bimolecular rate constant of 2.1 ×10 5 M –1 s –1 such that appearance of bromine signals complete consumption of ACTU. We were unable to trap any intermediate sulfur oxo-acids of ACTU on its oxidation pathway to N-acetylurea. As opposed to other substituted thioureas, none of its intermediates were stable enough to be isolated and detected. KEYWORDS Kinetics, mechanisms, oxyhalogen chemistry, s-oxygenation, bioactivation.
Highlights
The chemistry of thiourea and its derivatives has received considerable attention because of its important applications in synthesis of biologically-active compounds
Thiourea and its derivatives are a vast group of very active biological molecules.[2,3,4,5,6,7,8]. Major pathway to their bioactivation is oxidative and via S-oxygenation in which there is a successive addition of oxygen to the sulfur center until oxidative saturation is attained at sulfate.[9,10,11]
This is an activity not manifested by the parent thiourea. In this manuscript, on the oxidation mechanism of ACTU by acidic bromate and aqueous bromine
Summary
The chemistry of thiourea and its derivatives has received considerable attention because of its important applications in synthesis of biologically-active compounds. As a fluorescent substrate.[43] This is an activity not manifested by the parent thiourea We report, in this manuscript, on the oxidation mechanism of ACTU by acidic bromate and aqueous bromine. Its oxidation mechanism can be correlated with its physiological effect
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
