New and Surprising Experimental Results from the Oxidation of Sulfinic and Sulfonic Acids

Abstract

Thiourea, (H2N)2CS, aminoiminomethanesulfinic acid, H2N(HN)CSO2H (AIMSA), and aminoiminomethanesulfonic acid, H2N(HN=)CSO3H (AIMSOA) are all oxidized by mild oxidizing agents to a sulfate and an organic residue. AIMSA and AIMSOA are the postulated intermediates in the oxidation pathway of thiourea to sulfate. The oxidation of AIMSOA is accompanied by a cleavage of the C−S bond to form sulfate. Surprisingly, freshly prepared solutions of AIMSOA are oxidized by the common oxidants (oxyhalogens and halogens) at rates that are much slower than oxidation rates of AIMSA by the same oxidants. These results seem to suggest that AIMSOA may be structurally different from AIMSA and that the decomposition of AIMSOA to HSO3 - is the prerequisite to its oxidation. The oxidation pathway of AIMSA to SO4 2- also proceeds through the formation of HSO3 - and not predominantly through AIMSOA.

Mechanism Involving Hydrogen Sulfite Ions, Chlorite Ions, and Hypochlorous Acid as Key Intermediates of the Autocatalytic Chlorine Dioxide–Thiourea Dioxide Reaction

“…The rate coefficient of this reaction cannot be determined from our experiments because k 14 and k 15 were found to be in total correlation with each other. As we fixed k 15 , a value of (1.2 Ϯ 0.1) ϫ 10 5 m -1 s -1 could be calculated for the rate coefficient. The result for this reaction is in agreement with an independent result, [18] although the rate coefficients differ by a factor of 50.…”

“…[13] Some oxidation reactions of TDO have been controlled in acidic solutions. [14][15][16] The oxidations of TDO with chlorite ions, iodine, and bromine have been performed by Simoyi et al [15][16][17][18] Regrettably, the tautomerization of TDO, which seems to occur relatively slowly from (NH 2 ) 2 CSO 2 to NH 2 NHCSO 2 H [19,20] at low pH values, has so far not been taken into account in these reactions, though the two tautomers may have quite different reactivity towards chlorine dioxide and other chlorine-containing intermediates.…”

Sulfuric Acid Production on Europa: The Radiolysis of Sulfur in Water Ice

“…We also found that the presence of O 2 inhibits H 2 SO 4 production in ice, similar to Donaldson and Johnston's (1968) (Vairavamurthy and Zhou 1995), and sulfinic acid, SO 2 H 2 (DellaGuardia and Johnston 1980), as intermediates. SO 2 H 2 is produced in low temperature (12 K) photolysis (Fender et al 1991) and sulfinic acids are oxidized to sulfate (Makarov et al 1998). The final step, hydration of sulfuric acid, is highly exothermic and may occur simultaneously with three-body oxidation reactions.…”

Diaminothiadiazoles - Building Blocks for Macroheterocycles

“…Предложенный механизм согласуется с кинетическими данными, приведенными в литературе [59,60,62] для реакции окисления 2-имино-4-тиобиурета кислыми иодатами и броматами.…”

“…В литературе [60][61][62] авторы показали, что усиление окислительной способности реагента приводит к раскрытию пятичленного цикла с последующим образованием моно-, ди-и триоксида серы, в результате чего образуется гуанилмочевина. Этот вывод подтверждается результатами, описанными в работе [63] .…”