Reaction Of Iodine Research Articles

Tandem Ring-Contraction/Regioselective C–H Iodination Reaction of Pyridinium Salts

A facile route for direct access to the 4-iodopyrrole-2-carbaldehydes from pyridinium salts has been successfully developed, which undergoes cascade pyrrole-2-carbaldehydes construction/selective C4 position iodination process. Using Na2S2O8 as an oxidant and readily available sodium iodide as an iodine source, a variety of 4-iodopyrrole-2-carbaldehydes were obtained in good to excellent yields. Atom- and step-economy, good functional group tolerance, high regioselectivity, as well as mild conditions entail this transformation an alternative strategy for enriching pyrroles library.

Probing the Potential Energy Profile of the I + (H2O)3 → HI + (H2O)2OH Forward and Reverse Reactions: High Level CCSD(T) Studies with Spin-Orbit Coupling Included.

Three different pathways for the atomic iodine plus water trimer reaction I + (H2O)3 → HI + (H2O)2OH were preliminarily examined by the DFT-MPW1K method. Related to previous predictions for the F/Cl/Br + (H2O)3 reactions, three pathways for the I + (H2O)3 reaction are linked in terms of geometry and energetics. To legitimize the results, the "gold standard" CCSD(T) method was employed to investigate the lowest-lying pathway with the correlation-consistent polarized valence basis set up to cc-pVQZ(-PP). According to the CCSD(T)/cc-pVQZ(-PP)//CCSD(T)/cc-pVTZ(-PP) results, the I + (H2O)3 → HI + (H2O)2OH reaction is predicted to be endothermic by 47.0 kcal mol-1. The submerged transition state is predicted to lie 43.7 kcal mol-1 above the separated reactants. The I···(H2O)3 entrance complex lies below the separated reactants by 4.1 kcal mol-1, and spin-orbit coupling has a significant impact on this dissociation energy. The HI···(H2O)2OH exit complex is bound by 4.3 kcal mol-1 in relation to the separated products. Compared with simpler I + (H2O)2 and I + H2O reactions, the I + (H2O)3 reaction is energetically between them in general. It is speculated that the reaction between the iodine atom and the larger water clusters may be energetically analogous to the I + (H2O)3 reaction. The iodine reaction I + (H2O)3 is connected with the analogous valence isoelectronic bromine/chlorine reactions Br/Cl + (H2O)3 but much different from the F + (H2O)3 reaction. Significant difference with other halogen systems, especially for barrier heights, are seen for the iodine systems.

THAI experiments on iodine behavior in a room chain representing flow conditions in large containments

Iodine which can be released into the containment during a severe accident, is considered one of the most important nuclides with potential for public dose. Significantly different iodine concentrations can be expected in the individual compartments and rooms of large containments, due to geometrical constraints and the strong dependence of many iodine reactions on local thermohydraulic conditions. Such inhomogeneity may be relevant for organic iodide formation which depends on the concentration of deposited I2 and the dose rate.The objective of the two tests Iod-33 and Iod-35 was to measure the distribution of iodine along a convective flown-through room chain. This arrangement shall simulate the pathway of iodine from the locations of release (primary loop rupture) or formation (sump) along the plant rooms up to the dome of the containment and back. With respect to iodine, the aims were to measure the distribution and mixing of gaseous iodine in different rooms, the decrease of gaseous iodine by its deposition on painted surfaces, and the distribution of deposited iodine on the different painted surfaces.The two tests were performed in the two vessel THAI+ facility with additionally installed painted surfaces (painted with Gehopon epoxy paint) under superheated and condensing conditions. The main part of the painted surface area was provided in the form of painted steel sheets and arranged to form two intermediate floors within the THAI test vessel including small flow openings. Gaseous iodine was injected over several hours into the room chain in which a slow convection was established by means of differential wall heating.The gaseous I2 concentration inside the THAI+ facility increased continuously until the I2 injection was terminated. Simultaneously, the iodine deposition onto the painted surface increased. The gaseous I2 concentration decreased rapidly after stopping the I2 injection, in favor of a continuation of the I2 deposition on painted surfaces. The multi-compartment effect along the room chain has been demonstrated by the test results and the data allows for further development and validation of the I2/paint reaction model of severe accident codes.

Organo-catalyzed C2,3–H aminochalcogenation of indoles with secondary (aliphatic) amines

A direct C2,3–H difunctionalization of indoles with unactivated amines facilitated by the organo-chalconium catalyst generated through the reaction of iodine and chalconium reagents has been developed.

Comparative quantitative kinetic study of rapid iodination of thiazole and its methyl derivatives in aqueous medium

AbstractThe study provides a quantitative framework for the assessment of the relative reactivity of thiazole and its two methyl derivatives namely 2‐methylthiazole and 4‐methylthiazole towards iodination reaction. Thiazole and its derivatives have a wide range of industrial and medicinal applications attributed to the ability of thiazole to manifest substituents around the core scaffold. The kinetic study of the iodination reactions of these substrates helps in the above applications since kinetics is an important investigational tool in configuring the mechanism of the reaction. In the present work, molecular iodine (I2) and iodine monochloride (ICl) were used as reagents for the iodination of thiazole, 2‐methylthiazole, and 4‐methylthiazole in aqueous medium. The iodination reactions are rapid electrophilic substitution reactions and hence special technique known as hydrodynamic voltammetry was employed for the kinetic study. Iodine is the only electro‐reducible species in the reactions. As the solution is devoid of iodide ions, a decrease in the concentration of iodine is measured in terms of diffusion current using a rotating platinum electrode with a saturated calomel electrode (SCE) as a reference electrode. The reactivity correlation of substrates towards iodination reaction was quantitively assessed by determining the reaction rate constants and thermodynamic parameters. The study shows overall rate of iodination of 4‐methylthiazole is faster than 2‐methylthiazole which is faster than thiazole. The study helps to develop a mechanistic approach considering the effect of substituent present on the thiazole ring. The order of reactivity of the reagents was determined based on obtained rate constants and explained owing to the nature of the reagent.

Development and validation of an iodine plasma model for gridded ion thrusters

Iodine is emerging as an attractive alternative propellant to xenon for several electric propulsion technologies due to its significantly lower cost and its ability to be stored unpressurized as a solid. Because of the more complex reaction processes and energy-loss channels in iodine plasmas however, as well as the historical lack of reliable collision cross-section data, the development of accurate theoretical and numerical models has been hindered. Using recently calculated theoretical cross-sections, we present an iodine plasma model and perform a comparison with experimental data obtained from an iodine-fuelled gridded ion thruster. The model is in reasonable agreement with experimental measurements of the ion beam current, propellant mass utilization efficiency, and ion beam composition, and is able to quantitatively and qualitatively reproduce system behaviour as the input mass flow rate and RF power are varied. In addition, both the model and experiment show that the use of iodine can lead to a performance enhancement when compared with xenon. This occurs because of the combination of different iodine reaction processes, collision cross-section values, and inelastic energy thresholds which result in lower collisional energy losses, as well as an increased antenna-plasma power transfer efficiency for thrusters using a radio-frequency inductive coil.

Rechargeable Iodine Batteries: Fundamentals, Advances, and Perspectives.

Lattice distortion and structure collapse are two intrinsic issues of intercalative-type electrodes derived from repeated ion shuttling. In contrast, rechargeable iodine batteries (RIBs) based on the conversion reaction of iodine stand out for high reversibility and satisfying voltage output characteristics no matter when dealing with both monovalent and multivalent ions. Foreseeable performance superiorities lead to an influx of considerable focus and thus a renaissance in RIBs. This review provides a comprehensive overview of the fundamental chemistry of RIBs from the perspectives of physicochemical properties, conversion mechanism, and existing issues. Furthermore, we refine the optimization strategies for high-performance RIBs, focusing on physical adsorption and chemical interaction strengthening, electrolytes regulation, and nanoscale-iodine design. Then the pros and cons of tremendous RIBs are compared and specified. Ultimately, we conclude with remaining challenges and perspectives to our best knowledge, which may inspire the construction of next-generation RIBs.

A Green Alternative for the Direct Aerobic Iodination of Arenes Using Molecular Iodine and a POM@MOF Catalyst.

Iodoarenes are important precursors for fine chemicals and pharmaceuticals. The direct iodination of arenes using molecular iodine (I2) has emerged as an attractive green synthesis method. Most of the direct iodination protocols are still homogeneous systems that require harsh conditions and use or produce toxic products. We report a new heterogeneous catalytic route for the direct aerobic iodination of arenes under mild conditions using a PMoV2 polyoxometalate (POM) embedded in the metal-organic framework (MOF) MIL-101 (PMoV2@MIL-101). The catalyst shows full yield for the conversion of mesitylene to 2-iodomesitylene at a rate that is similar to the homogeneous POM system. Moreover, the catalyst is applicable for a wide range of substrates in an oxygen atmosphere without using any co-catalysts or sacrificial agents. To the best of our knowledge, this is the first report on designing a sustainable and green MOF-based heterogeneous catalytic system for the direct iodination reaction using molecular oxygen and iodine.

Stabilizing the Homopolycation (I4 )2+ with a Hexasulfate in (I4 )[S6 O19 ] and a Borosulfate in (I4 )[B(S2 O7 )2 ]2.

The reaction of elemental iodine and SO3 in a sealed glass ampoule yielded a turquoise-colored solution. At temperatures below 7 °C, deep red crystals of (I4 )[S6 O19 ] grow. With the addition of B2 O3 and pyridine-SO3 complex red crystals of (I4 )[B(S2 O7 )2 ]2 can be obtained after heating the mixture to 120 °C. The combination of an (I4 )2+ cation with oxoanions has previously not been observed. Both anions have a significant but different influence on the structural properties of the (I4 )2+ cation.

Syntheses and crystal structures of a nitro-anthracene-isoxazole and its oxidation product.

The syntheses and structures of an unexpected by-product from an iodination reaction, namely, ethyl 5-methyl-3-(10-nitro-anthracen-9-yl)isoxazole-4-carb-oxy-l-ate, C21H16N2O5, (I), and its oxidation product, ethyl 3-(9-hy-droxy-10-oxo-9,10-di-hydro-anthracen-9-yl)-5-methyl-isoxazole-4-carboxyl-ate, C21H17NO5 (V) are described. Compound (I) crystallizes with two mol-ecules in the asymmetric unit in which the dihedral angles between the anthracene fused-ring systems and isoxazole ring mean planes are 88.67 (16) and 85.64 (16)°; both mol-ecules feature a disordered nitro group. In (V), which crystallizes with one mol-ecule in the asymmetric unit, the equivalent dihedral angle between the almost planar anthrone ring system (r.m.s. deviation = 0.029 Å) and the pendant isoxazole ring is 89.65 (5)°. In the crystal of (I), the mol-ecules are linked by weak C-H⋯O inter-actions into a three-dimensional network and in the extended structure of (V), inversion dimers linked by pairwise O-H⋯O hydrogen bonds generate R 2 2(14) loops.

New Chromatin Run-On Reaction Enables Global Mapping of Active RNA Polymerase Locations in an Enrichment-free Manner.

The development of a simple and cost-effective method to map the distribution of RNA polymerase II (RNPII) genome-wide at a high resolution is highly beneficial to study cellular transcriptional activity. Here we report a mutation-based and enrichment-free global chromatin run-on sequencing (mGRO-seq) technique to locate active RNPII sites genome-wide at near-base resolution. An adenosine triphosphate (ATP) analog named N6-allyladenosine triphosphate (a6ATP) was designed and could be incorporated into nascent RNAs at RNPII-located positions during a chromatin run-on reaction. By treatment of the run-on RNAs with a mild iodination reaction and subjection of the products to reverse transcription into complementary DNA (cDNA), base mismatch occurs at the original a6A incorporation sites, thus making the RNPII locations detected in the high-throughput cDNA sequencing. The mGRO-seq yields both the map of RNPII sites and the chromatin RNA abundance and holds great promise for the study of single-cell transcriptional activity.

EFFECTIVE SYNTHESIS OF 5-IODOMETHYL-2-PHENYLIMINOTHIAZOLIDINE

Thioamides and thioureas are interesting building blocks for the synthesis of azaheterocycles with valuable biological properties. The electrophilic cyclization of N-alkenylthioamides and N-alkenylthioureas is one of the methods of their synthesis. It is known that halogen-induced cyclization of N-alkenylthioamides and thioureas leads to the annealing of 5- or 6-membered cycles. In particular, the cyclization of allylthioamides in the presence of halogen gives halomomethylthiazolines. N-allyl-N-arylthioureas react with halogens, arylselenyl chloride or aryl tert-trichloride to form thiazolidine rings.
 The three-component reaction between unsaturated amine, isocyanate or isothiocyanate and halogen is the one of the methods for the synthesis of halogenated oxazolines or thiazolines. This reaction considered the using of propargyl amine, isocyanate and halogen, which leads to the formation of halomomethylidenoxazolidine or halomomethylidenethiazolidine. The formed vinyl halides are universal building blocks in organic synthesis due to their ability to modify. The aim of this work is to study the course of the three-component reaction between allylmethylamine, phenylisothiocyanate and iodine. The use of allylamine will allow to introduce a halogenomethyl group into the azaheterocycle, which will greatly facilitate its functionalization.
 The reaction of equimolar amounts of phenylisothiocyanate, allylmethylamine and iodine was performed in acetonitrile. This led to an increase in the yield of the target reaction product. Increasing the reaction temperature from room to 50 ° C also increased the yield. The 5-iodomethyl-3-methyl-2-phenylimino-1,3-thiazolidine was isolated as a light brown oil after treatment of the reaction mixture with potassium carbonate. Obviously, the process of iodocyclization is preceded by the formation of N-allyl thiourea, which effectively enters into the electrophilic heterocyclization reaction with the participation of an additional nucleophilic center - a sulfur atom.
 Thus, the resulting three-component reaction of phenylisothiocyanate, allylmethylamine and iodine is an effective method for the synthesis of bioperspective iodomethylthiazolidine, submitted for further functionalization.
 Keywords: electrophilic cyclization; allylmethylamine, three-component reaction; iodomethylthiazolidine.

Ionic Reactivity of 2-Isocyanoaryl Thioethers: Access to 2-Halo and 2-Aminobenzothia/Selenazoles.

An ionic cascade insertion/cyclization reaction of thia-/selena-functionalized arylisocyanides has been successfully developed for the efficient and practical synthesis of 2-halobenzothiazole/benzoselenazole derivatives. This synthetic protocol, incorporating a halogen atom when forming the five-membered ring of benzothia/selenazoles, is different from the existing ones, where halogenation of the preformed benzothia/selenazole precursors happens. Additionally, a facile access to 2-aminobenzothiazoles is also achieved by the one-pot cascade reaction of 2-isocyanoaryl thioethers, iodine, and amines.

Colorimetric detection of Aflatoxin B1 by using smartphone-assisted microfluidic paper-based analytical devices

Aflatoxin B 1 (AFB 1 ) is a powerful carcinogen, and the pollution it causes has become a global public health safety issue. Therefore, microfluidic paper-based analytical devices (μPADs) with smartphones to read colorimetric signals were constructed for rapid AFB 1 detection. The colorimetric mechanism of μPADs was based on the common starch–iodine reaction, and the addition of gelatin/chitosan enhanced the colorimetric effect. During detection and analysis, the competitive analysis occurred in the process of AFB 1 monoclonal antibody's recognition of free AFB 1 and functionalized antigen. The glucose oxidase-labeled IgG was used as the secondary antibody. Hydrogen peroxide, an oxidation product of the glucose, caused a chroma change in μPADs. Simultaneously, the change in chroma was consistent with the change in AFB 1 concentration. Under the best optimized conditions, the limits of detection and quantitation of AFB 1 in the buffer were 9.45 and 12.00 ng mL −1 , respectively. A comparison of the detection performance of commercial kits with that of the method introduced herein confirmed the superiority of our method in actual food samples with known AFB 1 concentrations. This colorimetric μPADs analysis met the detection requirements of some countries, such as China, and had great potential for development in the direction of daily extensive food safety control and environmental monitoring. • Portable and low-cost smartphone-based microfluidic paper-based analytical devices (μPADs). • The colorimetric μPAD detection system can detect aflatoxin B1 as low as 9.45 ng mL −1 through Lab data analysis. • The colorimetric mechanism is based on the common starch–iodine reaction. • The addition of gelatin and chitosan mixture enhances the colorimetric effect.

Application of Palm Wine Yeast Species in Beer Brewing

Brewing is found to be one of the lucrative businesses in Nigeria. The brewer’s yeast commonly known as Saccharomyces cerevisiae is always imported and its price affects the price of the products drastically. In this work, yeast strain was isolated from Palm Wine, identified as Saccharomyces cerevisiae and used as an alternative in beer brewing. The isolate (SPW) was seen to poses many similar characteristics of the brewer’s yeast (SCT) imported from foreign countries. The isolated and enriched yeast was employed in the laboratory for the production of beer. Results showed that both organisms failed to ferment melibiose and raffinose but fermented glucose, maltose, fructose, sucrose, and galactose. They survived at stress conditions for temperature and cell osmotic pressure in high concentration of ethanol and sugar. They showed good flocculation ability of 97%, and 82% respectively. Their percentage viability was 96.66% and 91.00% respectively with no production of hydrogen sulfide gas. The property of wort prepared for brewing was; pH of 5.82, specific gravity of 1.050 and iodine reaction showed yellow colour. After fermentation, the specific gravity was 1.001 and 1.010 for SPW and SCT respectively while alcohol content was 6.53% and 5.25% respectively. Wort was fermented at 28 ± 2oC for six days and the product beer showed apparent extract of 3.4oP and 4.8oP, Real extract of 4.8oP and 6.55oP, real degree of fermentation of 58.44% and 61.22% for SPW and SCT respectively. Statistical analysis showed that yeast strain isolated from palm wine after enrichment had great potential when compared to brewer’s yeast strain in beer production attributes (p < 0·05).

Thermodynamics and Kinetic Modeling of the ZnSO4·H2O Thermal Decomposition in the Presence of a Pd/Al2O3 Catalyst

The sulfur–iodine thermochemical water-splitting cycle is a promising route proposed for hydrogen production. The decomposition temperature remains a challenge in the process. Catalysts, such as Pd supported on Al2O3, are being considered to decrease reaction temperatures. However, little is known regarding the kinetic behavior of such systems. In this work, zinc sulfate thermal decomposition was studied through non-isothermal thermogravimetric analysis to understand the effect of a catalyst within the sulfur–iodine reaction system context. The findings of this analysis were also related to a thermodynamic assessment. It was observed that the presence of Pd/Al2O3 modified the reaction mechanism, possibly with some intermediate reactions that were suppressed or remarkably accelerated. The proposed model suggests that zinc sulfate transformation occurred in two sequential stages without the Pd-based material. Activation energy values of 238 and 368 kJ·mol−1 were calculated. In the presence of Pd/Al2O3, an activation energy value of 204 kJ·mol−1 was calculated, which is lower than observed previously.

Kinetics and mechanism of I(+ 3) reactions and consequences for other iodine reactions

This article presents new kinetic studies of the disproportionation of I(+ 3) and of its oxidation by H2O2. It also provides an update of the previously proposed model for reactions of iodine compounds with oxidation numbers from − 1 to + 5 with each other and with H2O2. This model explains the kinetics of several reactions, including the oxidation of iodine by H2O2. We show that the reduction of HOI by H2O2 results from \({\text{HOI }} + {\text{ H}}_{{2}} {\text{O}}_{{2}} \to {\text{HOOI }} + {\text{ H}}_{{2}} {\text{O}}\) followed by the reversible reaction \({\text{HOOI}} \rightleftharpoons {\text{I}}^{ - } + {\text{ H}}^{ + } + {\text{ O}}_{{2}}\). An analysis of previous measurements of the kinetic constant k(HOI + H2O2) explains the large differences between the values proposed in the literature and gives k(HOI + H2O2) = 6 M−1 s−1. The reversibility of the reaction \({\text{HOOI}} \rightleftharpoons {\text{I}}^{ - } + {\text{ H}}^{ + } + {\text{ O}}_{{2}}\) suggests a new explanation for the effect of oxygen on the Bray–Liebhafsky reaction. H2O2 would oxidize HOOI by a radical mechanism.

Effects of increased viscosity on micromixing in rotor–stator spinning disk reactors

In this paper, micromixing is investigated in two Spinning Disk Reactors for liquids with increased viscosity. Glycerol and CMC were used as viscosity modifiers and micromixing characterization was performed by means of the Villermaux–Dushman method. For the first time, the effects of increasing the pH of the bulk solution leading to the disproportionation reaction of iodine are successfully modeled. A kinetic model is proposed to account for the presence of glycerol as a co-solvent. Micromixing efficiency decreases with increasing viscosity, yet the results are in line with the proportionality to the Kolmogorov timescale. The viscosity can be significantly increased using CMC as a viscosity modifier; however, due to the viscoelastic behavior of CMC, the effective viscosity decreases in the high shear environment inside the reactor. This leads to a much higher micromixing efficiency. It is shown that micromixing times can be estimated provided that the rheology of the liquids is known.

Quality Assessment of Ascorbic Acid Tablet Formulations and Comparative Analysis with Edible Fruits

Background: Ascorbic acid is a vitamin, soluble in water and essential for human health. It plays vital role in collagen production, iron absorption, wound healing, osteogenesis, and scurvy treatment. Objective: The study aimed to evaluate the physicochemical features of ascorbic acid oral tablet formulations and compare the amount found in natural sources to that found in commercial brands. Method: The study used six brands of ascorbic acid tablets. The drugs were analyzed using the iodometric titration employing the oxidation-reduction reaction of ascorbic acid and iodine as well as assessing uniformity of weight, hardness, dissolution, friability and disintegration. Results: The fruits were obtained from the fruit market. All the brands of Vitamin C tablets used were within their shelf-lives, standard British pharmacopeia range. Brand E had the highest weight (910.26 mg) and more variation (<2.98 ± 4.23), brand C had the highest percentage friability (0.924%), while D showed lower degree of hardness (0.065%) compared to other brands. Brand D had the highest percentage of drug release (102.973%). Brand F disintegrated at about 21:06 minutes. From the ten samples purchased, none had 100% ascorbic acid though brand B had almost 100% (99.5 mg). Brand E had the least concentration (89.5 mg). Conclusion: The results shows that all the tablets had appreciable percent of ascorbic acid. Strawberries had higher percentage of ascorbic acid among the fruits, followed by orange, papaya, pineapple, mango, kiwi and lemon, respectively.

Single-step construction of an acetoxypyrroloindole skeleton via tandem iodocyclization/acetoxylation of indoles.

A method for the synthesis of C3a acetoxy hexahydropyrrolo[2,3-b]indole derivatives via a PhI(OAc)2/nBu4NI mediated tandem iodocyclization/acetoxylation has been developed. The newly developed synthetic strategy features the single-step assembly of various C3a acetoxylated tetrahydropyrrole-, tetrahydrofuran-, and lactone-fused indolines under mild reaction conditions, which enabled efficient asymmetric synthesis of (-)-protubonine B.