Structure and Property Investigations of TDO in Aqueous Phase by Density Functional Theory, UV Absorption, and Raman Spectroscopy

Shao, Jianzhong; Liu, Xiaoyun; Chen, Pin; Wu, Qiuxia; Zheng, Xuming; Pei, Kemei

doi:10.1021/jp502375r

Cited by 14 publications

(11 citation statements)

References 17 publications

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“…One reasonable possibility is that TDO changes from a less reactive form (oligomeric) to a more reactive form upon dissolution of the solid in aqueous solution. [38] Unfortunately, there is no way to distinguish between these possibilities in our kinetic measurements; consequently, TDO and AIMSA in the kinetic model may also mean two different forms of thiourea dioxide, not specifically the dioxide and the aminoimino form. Our calculations also indicated that the transformation of two different forms of TDO is accelerated by an increase of pH, which is reflected by the k 1 Ј value indicated in Table 2.…”

Section: Discussionmentioning

confidence: 99%

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

Horváth

Duan

et al. 2015

Eur J Inorg Chem

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The kinetics of the chlorine dioxide–thiourea dioxide reaction was investigated by monitoring absorbance–time profiles at λ = 360 nm. Under acidic conditions, the primary carbon‐containing product is cyanamide, not urea as considered previously for many oxidation reactions of thiourea dioxide. Increase of the rate of the reaction by an increase of pH can be readily explained by the slow pH‐dependent formation of a more reactive form of thiourea dioxide (TDO) that is produced steadily and unavoidably as the stock TDO solution ages. We have also found that the absorbance–time profiles of the chlorine dioxide–TDO reaction are sigmoidal with excess TDO. The addition of methionine as a hypochlorous acid scavenging agent inhibits the reaction significantly, whereas the addition of chlorite ions and trace amounts of hydrogen sulfite ions accelerates the decay of chlorine dioxide. On the basis of these experiments, a sixteen‐step kinetic model involving hypochlorous acid, chlorite ions, and hydrogen sulfite ions as key intermediates that provide an autocatalytic cycle is proposed to account for the overall kinetic behavior observed, including the slow rearrangement of TDO.

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Section: Discussionmentioning

confidence: 99%

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

Horváth

Duan

et al. 2015

Eur J Inorg Chem

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“…It should be noted that aging effect can be explained not only by formation of AIMSA, but also an initial formation of TDO oligomers in aqueous solution to be different from that of found in solid state. Indeed, recent investigations of TDO in aqueous solutions by DFT, UV, and Raman spectroscopy showed that when TDO is dissolved in water its molecular structure changes significantly 31b…”

Section: Stability and Reactivitymentioning

confidence: 99%

Recent Developments in the Chemistry of Thiourea Oxides

Макаров

Horváth

Silaghi-Dumitrescu

et al. 2014

Chemistry A European J

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Thiourea dioxide is one of the best known, important, and stable products of thiourea oxidation. This compound has long been considered as an effective reducing agent for many years. Traditional areas of its application include the textile and paper industries. In recent years, however, thiourea dioxides and trioxides have been widely used in new fields including organocatalytic, polymerization, and phase-transfer reactions; reduction of graphene and graphite oxides; bitumen modifications; synthesis of guanidines and their derivatives; and studying nonlinear dynamical phenomena in chemical kinetics. The review gives a detailed survey of the latest developments and main trends in the chemistry and application of thiourea mon-, di-, and trioxides.

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“…The first important fact that one should take care of is that TDOeven acidic conditionsrelatively slowly but steadily rearranges into a more reactive form, whose reactions are reported to be much faster with the corresponding oxidants than the original form of TDO. It is still unresolved whether this rearrangement is the consequence of a tautomerism , or of an oligomer–monomer degradation or even of an aminoimino–carbenoid transformation; it is indisputably clear that this characteristic must be taken into consideration when the kinetics of the redox transformation of TDO is designed to be investigated. Overlooking the possible kinetic effect of aging is not the only inconsistency that may be found.…”

Section: Introductionmentioning

confidence: 99%

Exact Concentration Dependence of the Landolt Time in the Thiourea Dioxide–Bromate Substrate-Depletive Clock Reaction

et al. 2019

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The thiourea dioxide (TDO)–bromate reaction has been reinvestigated spectrophotometrically under acidic conditions using phosphoric acid–dihydrogen-phosphate buffer within the pH range of 1.1–1.8 at 1.0 M ionic strength adjusted by sodium perchlorate and at 25 °C. The title system shows a remarkable resemblance to the classical Landolt reaction, namely, the clock species (bromine) may only appear after the substrate TDO is completely consumed. Thus, the title system can be classified as substrate-depletive clock reaction. Despite the well-known slow rearrangement characteristic of TDO in acidic solution, it is surprisingly found that the Landolt time of the title reaction does not depend at all on the age of TDO solution applied. It is, however, shown experimentally that the inverse of Landolt time linearly depends on the initial bromate concentration as well as on the square of the hydrogen ion concentration. In addition to this, it is also noticed that dihydrogen phosphate markedly affects the Landolt time as well, and this feature may easily be taken into consideration by the H2PO4 – dependence of the rate of bromate–bromide reaction quantitatively. Based on the experiments, a simple three-step kinetic model is proposed from which a complex formula is derived to indicate the exact concentration dependence of the Landolt time.

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Structure and Property Investigations of TDO in Aqueous Phase by Density Functional Theory, UV Absorption, and Raman Spectroscopy

Cited by 14 publications

References 17 publications

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

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

Recent Developments in the Chemistry of Thiourea Oxides

Exact Concentration Dependence of the Landolt Time in the Thiourea Dioxide–Bromate Substrate-Depletive Clock Reaction

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