Iodic Research Articles

Synthesis and reactive characterization of aluminum iodate hexahydrate crystals [Al(H2O)6](IO3)3(HIO3)2

A crystalline aluminum iodate acid salt has been synthesized from aluminum particles dissolved in iodic acid solution. The precipitate from solution is aluminum iodate hexahydrate [Al(H2O)6](IO3)3(HIO3)2, as confirmed by X-ray diffraction (XRD) analysis. The method of synthesis first dissolves iodine oxide in water, creating an IO3− solution with pH < 0.2. Aluminum nanoparticles are added to the IO3− solution and aluminum iodate hexahydrate (AIH) crystals precipitate. The bulk density of the crystalline AIH and Al composite is dependent on the initial water to aluminum concentration ratio during synthesis. Reactivity is characterized in terms of flame speed with measurements purposefully designed to capture less than 1% light emission, resulting in speeds as high as 3200m/s for AIH+Al composite with a calculated density of 3.43g/cc.

Pretreatment of Lithium Surface by Using Iodic Acid (HIO3) To Improve Its Anode Performance in Lithium Batteries.

Iodic acid (HIO3) was exploited as the effective source to build an artificial solid-electrolyte interphase (SEI) on the surface of Li anode. On one hand, HIO3 is a weak solid-state acid and can be easily handled to remove most ion-insulating residues like Li2CO3 and/or LiOH from the pristine Li surface; on the other hand, both the products of LiI and LiIO3 resulted from the chemical reactions between Li metal and HIO3 are reported to be the ion-conductive components. As a result, the lower voltage polarization and impedance, longer cycling lifetime and higher Coulombic efficiency have been successfully achieved in the HIO3-treated Li-Li and Li-Cu cells. By further using the HIO3-treated Li anode into practical Li-S batteries, the impressive results also have been obtained, with average discharge capacities of 719 mAh g-1 for 200 cycles (0.2 C) and 506 mAh g-1 for 500 cycles (0.5 C), which were better than the Li-S batteries using the pristine Li anode (552 and 401 mAh g-1, respectively) under the same conditions.

Aerosol synthesis of phase pure iodine/iodic biocide microparticles

Abstract

An Evaluation of Corrosion Inhibitors for Use in Acid Decapsulation of Samples with Silver Bond Wires

Abstract Silver bond wires can be protected from damage during acid decapsulation by injecting a corrosion inhibitor into the acid stream. Recent experiments show that the injection of an iodic acid solution is effective over a wide range of process parameters, including etch time, etch temperature, and the amount of inhibitor injected. The results presented in the article are based on the use of a 0.3 M iodic acid solution and the decapsulation of parts containing silver alloy wire. However, similar results have been achieved on test samples with pure silver wire using a higher concentration inhibitor solution. Both solutions have very long shelf life and are relatively safe to handle.

Tailoring surface conditions for enhanced reactivity of aluminum powders with solid oxidizing agents

The effect of processing liquids on particle surface hydration and subsequent reactivity of mixtures containing aluminum (Al) with different oxidizing agents was investigated. Recently, polar processing liquids were shown to significantly increase the surface hydration layer on Al particles and effect the reactivity of Al combined with polytetrafluoroethylene (PTFE). Processing mixtures of Al and PTFE using hexane (e.g., a non-polar liquid) limited surface hydration and produced significantly lower flame speeds than the same mixture processed in isopropanol (e.g., a polar liquid). Increased surface hydroxyl concentration was linked to higher exothermic behavior within a pre-ignition reaction (PIR) which may contribute to higher overall flame speed. This study extends the previous analysis toward assessing the influence of processing liquid on reactivity of aluminum with other oxidizing agents, specifically CuO, MoO3 and I2O5. Results from DSC analysis show no PIR kinetics associated with Al and CuO or MoO3, and Al+ CuO showed no difference in reactivity as a function of processing liquid. But, MoO3 FTIR shows modified surface structures after treatment in a polar solvent. Correspondingly, Al+MoO3 processed in polar solvent exhibited increased flame speed by 19% when compared to Al+MoO3 processed in a non-polar liquid. For Al+I2O5, water in polar processing liquids produces various hydrated states of iodic acid (i.e., HIO3 and HI3O8). Changing the hydration state of I2O5 significantly impacts reactivity. Results from this study confirm that carrier fluid used to process Al with metal oxides can also alter the surface structure of the metal oxide, thereby promoting greater reactivity with Al. A polar carrier fluid not only modifies the surface of Al but also hydration sensitive metal oxides such as MoO3 and correspondingly promotes greater reactivity.

The water–iodine oxide system: a revised mechanism for hydration and dehydration

Iodic acids are widely studied in atmospheric and biological applications but their inherent hydrophilic properties introduce complexities that affect their functionality and reactivity.

Pure gold dissolution in dilute chloric, bromic or iodic acid solution containing abundant halide ions

The pure gold dissolution has been explored in (dilute) chloric, bromic, or iodic acid (HXO3, X = Cl, Br, I) aqueous solution containing abundant halide ions at 60 °C. It has been found that mixtures between sodium chlorate and HCl (NaClO3 + HCl ⇆ HClO3 + NaCl) in 20 mL are effective media for the dissolution of pure gold-wire (99.95 %, ca. 20 mg, 0.25 mm diameter). The gold-wire dissolution is much more enhanced by HBr than HCl in NaClO3 solution. At 0.50 mol dm-3 NaClO3, for instance, log (k/s-1) values are -5.11 and -3.40 (ca. 50-fold increase) for 1.0 mol dm-3 HCl and HBr, respectively, where “pseudo” first-order dissolution rate constants (k/s-1) have been evaluated by the changes in the mass of gold-wire. In HClO3 solution containing abundant halide ions (X- = Cl-, Br-), the Au metal should be oxidized mainly by X2 to be AuX4-, where X2 is produced by the oxidizing power from HClO3, just as dilute HNO3 (< 2 mol dm-3) containing abundant NaCl. In NaBrO3 solution, however, HBr does not acquire any superiority to HCl in the gold dissolution. In NaIO3 solution, the effect of HX at the lower concentrations (< 0.03 mol dm-3) of NaIO3 increases in the order of HCl < HBr < HI. The gold dissolution in hypochlorous acid (HClO) containing halide ions has been also examined as the reference. A new diagram has been proposed in order to verify that even the conjugate anion (ClO3- or NO3-) from a strong acid (HClO3 or HNO3) is subject to be protonated in the “aqueous solution” modified by electrolytes of very high concentrations (> ~ 5 mol dm-3).

Observation of new particle formation and measurement of sulfuric acid, ammonia, amines and highly oxidized organic molecules at a rural site in central Germany

Abstract. The exact mechanisms for new particle formation (NPF) under different boundary layer conditions are not known yet. One important question is whether amines and sulfuric acid lead to efficient NPF in the atmosphere. Furthermore, it is not clear to what extent highly oxidized organic molecules (HOMs) are involved in NPF. We conducted field measurements at a rural site in central Germany in the proximity of three larger dairy farms to investigate whether there is a connection between NPF and the presence of amines and/or ammonia due to the local emissions from the farms. Comprehensive measurements using a nitrate chemical ionization–atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometer, a proton-transfer-reaction mass spectrometer (PTR-MS), particle counters and differential mobility analyzers (DMAs), as well as measurements of trace gases and meteorological parameters, were performed. We demonstrate here that the nitrate CI-APi-TOF is suitable for sensitive measurements of sulfuric acid, amines, a nitrosamine, ammonia, iodic acid and HOMs. NPF was found to correlate with sulfuric acid, while an anti-correlation with RH, amines and ammonia is observed. The anti-correlation between NPF and amines could be due to the efficient uptake of these compounds by nucleating clusters and small particles. Much higher HOM dimer (C19/C20 compounds) concentrations during the night than during the day indicate that these HOMs do not efficiently self-nucleate as no nighttime NPF is observed. Observed iodic acid probably originates from an iodine-containing reservoir substance, but the iodine signals are very likely too low to have a significant effect on NPF.

Synthetic utility of iodic acid in the oxidation of benzylic alcohols to aromatic aldehydes and ketones

Various primary and secondary benzylic alcohols were efficiently oxidized to aromatic aldehydes and aromatic ketones with iodic acid in DMF at 60 °C for 2 h and with iodic acid in the presence of TEMPO (5 mol %) in DMF at room temperature, respectively. The former method was effective for the oxidation of sterically hindered alcohols at 60 °C and the latter method was effective for the oxidation of less sterically hindered alcohols at room temperature.

A theoretical study of the microhydration of iodic acid (HOIO2)

The structures, energetics, and thermodynamic properties of HIO3 isomers (HOOOI, HOOIO, HOIO2, and HIO3) have been computed using CCSD(T)/CBS theoretical method. The spin orbit corrections (SOC) have also been evaluated for the each iodine-containing molecule. The SOC value decreases as the iodine valence increases within the molecule. The results revealed that HOIO2 was the most stable form and that HOOOI was the next most stable isomer. The standard enthalpies of formation at 298K have been derived from IO+HO2 and OH+OIO dissociation pathways. At the CCSD(T)/CBS level on B3LYP geometries, the recommended ΔfH°298K is (−95.4±0.3)kJmol−1 for HOIO2, and its computed S°298K andCp (300K) values are respectively 339.12 and 75.28Jmol−1K−1. Further, monohydrated and dihydrated complexes of iodic acid have been investigated using DFT and wavefunction methods. Three and six mono- and di-hydrated complexes, respectively, have been identified. The hydrogen bonded complexes (HOIO2_1wa and HOIO2_2wa) are the lowest lying structures. The thermodynamics of dihydrates have been calculated from the total hydration of iodic acid (HOIO2+2H2O). Mono- and di-hydration of iodic acid is a favored process at tropospheric and ambient conditions with the formation of HOIO2_1wa and HOIO2_2wa at T⩽310K. The positive Gibbs free energies at high temperatures indicate that gas-phase iodic acid would not be present in a hydrated form inside the nuclear containment building of a pressurized water reactor.

Molecular-scale evidence of aerosol particle formation via sequential addition of HIO3.

Homogeneous nucleation and subsequent cluster growth leads to the formation of new aerosol particles in the atmosphere1. Nucleation of sulphuric acid and organic vapours is thought to be responsible for new particle formation over continents1,2 while iodine oxide vapours have been implicated in particle formation over coastal regions3–7. Molecular clustering pathways involved in atmospheric particle formation have been elucidated in controlled laboratory studies of chemically simple systems2,8–10. But no direct molecular-level observations of nucleation in atmospheric field conditions involving either sulphuric acid, organic or iodine oxide vapours have been reported to date11. Here we report field data from Mace Head, Ireland and supporting data from northern Greenland and Queen Maud Land, Antarctica that allow for the identification of the molecular steps involved in new particle formation in an iodine-rich, coastal atmospheric environment. We find that the formation and initial growth process is almost exclusively driven by iodine oxoacids and iodine oxide vapours with average resulting cluster O:I ratios of 2.4. Based on the high O:I ratio, together with observed high concentrations of iodic acid, HIO3, we suggest that cluster formation primarily proceeds by sequential addition of iodic acid HIO3, followed by intra-cluster restructuring to I2O5 and recycling of water in the atmosphere or upon drying. Overall, our study provides ambient atmospheric molecular-level observations of nucleation, supporting the previously suggested role of iodine containing species in new particle formation3–7, 12–18, and identifies the key nucleating compound.

Reactive characterization of anhydrous iodine (v) oxide (I2O5) with aluminum: amorphous versus crystalline microstructures

Iodine pentoxide (I2O5) is typically synthesized by dehydration of iodic acid such that the produced material inherently includes hydrated iodic acid species that facilitate further water absorption when exposed to ambient environments. This is a detrimental property for I2O5 powder used in energetic systems. A dry-approach for synthesizing I2O5 with either crystalline (nano C I2O5) or amorphous (nano A I2O5) structure was used for this study and compared to the commercially available material. This synthesis approach enabled isolation of the microstructure as a variable to better understand water absorption behavior of I2O5 and associated reactivity. Material characterization included BET, SEM, TEM, and XRD as well as equilibrium analyses using DSC and TGA along with flame speeds. Results show that nano C I2O5 reacts less with atmospheric water and has a more anhydrous behavior than the crystalline I2O5 powder commercially available. The nano A I2O5 also produced a distinct pre-ignition reaction (PIR) and evidence for smaller PIRs are shown for all mixtures of Al with I2O5. These properties along with increased specific surface area of the nano C I2O5 and nano A I2O increased reactivity and enhanced combustion with Al when compared with commercial I2O5.

A rapid, mild, and efficient method for C-5 iodination/thiocyanation of 2-aminothiazoles

GRAPHICAL ABSTRACT

Experimental and Kinetic Study of Esterification of Acrylic Acid with Ethanol Using Homogeneous Catalyst

Abstract Esterification of acrylic acid with ethanol, catalyzed by sulfuric acid has been carried out in stirred batch reactor under atmospheric pressure. Different parameters such as effect of initial molar ratios of the reactants, effect of catalyst concentration, initial water and effect of temperature has been studied in the batch reactor. Different catalyst loading system (1–3 vol%), reaction temperatures (50–70 °C), initial reactants molar ratio (1:1–1:3) and water concentration in feed (0–20 vol%) was used in the reaction system. The temperature dependence is exponential and expressed by Arrhenius type of relationship. Kinetics parameters such as equilibrium constant, rate constants, activation energy and reaction enthalpy and entropy were estimated by experimental data. The rate equation has a remarkable fit to the data and was able to describe the behavior of the system at various reaction temperatures. Hydrochloric acid (HCl) and hydro iodic acid (HI) were also compared with sulphuric acid as catalyst for esterification of acrylic acid with ethanol. Sulphuric acid was found to be more efficient catalyst for esterification as it induces the maximum conversion of acrylic acid.

Compatible Mechanism for a Simultaneous Description of the Roebuck, Dushman, and Iodate-Arsenous Acid Reactions in an Acidic Medium.

The iodine-arsenous acid (Roebuck), iodide-iodate (Dushman), and iodate-arsenous acid reactions have been studied simultaneously by a stopped-flow technique by monitoring the absorbance-time profiles at the isosbestic point of the I2/I3(-) system (468 nm). Using the well-accepted rate coefficients of iodine hydrolysis, we have proven that iodine is the kinetically active species of the iodine-arsenous acid reaction. Strong iodide inhibition of this system is explained by a rapidly established equilibrium between iodine and arsenous acid to produce an iodide ion, a hydrogen ion, and a short-lived intermediate H2AsO3I, which is shifted far to the left. Taking into consideration the generally accepted kinetic model of the Dushman reaction where I2O2 plays a key role to account for all of the most important observations in this subsystem and a sequence of simple formal oxygen-transfer reactions between arsenous acid and iodic acid as well as iodous acid and hypoiodous acid, we propose a 13-step comprehensive kinetic model, including seven rapidly established equilibria with only six fitted parameters, that is able to explain all of the most important characteristics of the kinetic curves of all of the title systems both individually and simultaneously.

Conditions for obtaining backward collinear isotropic acousto-optic interaction in germanium and iodic acid crystals

The possibility of experimentally obtaining backward collinear isotropic acousto-optic interaction based on bulk ultrasonic waves and terahertz electromagnetic waves is considered. The magnitudes of the acousto-optic figure of merit and the corresponding acoustic frequencies are calculated for the basic crystallographic axes in germanium and iodic acid crystals. The acousto-optic parameters of both crystals are compared.

Ritter-type amination of C-H bonds at tertiary carbon centers using iodic acid as an oxidant.

The Ritter-type amination of a tertiary C-H bond using iodic acid (HIO3) as an oxidant, in the presence of N-hydroxyphthalimide (NHPI) is reported. This operationally simple method is conducted under metal-free conditions, is scalable, and efficiently provides valuable α-tertiary amine derivatives.

Anisotropic light diffraction in a biaxial crystal of alpha-iodic acid

A program for calculating characteristics of acousto-optic interaction in biaxial crystals is developed and used to analyze light diffraction by ultrasound in an iodic acid crystal. Crystal cuts with maximum acousto-optic figures of merits are found. It is shown that in the region of the optical axes the frequency dependences of the Bragg angles under anisotropic diffraction are substantially different from those in uniaxial crystals.

Application of track-etched membranes to synthesis of microcrystalline dielectric structures

The formation of oriented nanostructures of iodic acid (HIO3) on track-etched membranes has been studied. The study has shown that the method of forced filtration of supersaturated crystallization solutions through track membrane pores can be used to grow needlelike faceted microcrystals that have the cross size and preferential growth direction corresponding to those of the pores.

Spectrophotometric Methods for Determination of Tranexamic Acid and Etamsylate in Pure Form and Pharmaceutical Formulation

Background: Tranexamic acid and etamsylate drugs belong to a group of antifibrinolytics. Tranexamic Acid (TRA) is the most potent antifibrinolytic lysine analogue used in a broad spectrum of peri-and postoperative interventions and bleeding disorders. The administration of TRA is associated with a reduction in bleeding due to its inhibitory effect on clot breakdown (fibrinolysis). Etamsylate (ESL) is a haemostatic agent that appears to maintain the stability of the capillary wall and correct abnormal platelet adhesion. It is given for the prophylaxis and control of haemorrhages from small blood vessels. Objective: Two simple and sensitive spectrophotometric methods are described for the determination of tranexamic acid (TRA) and etamsylate (ESL) drugs in pure form and pharmaceutical preparations. Materials and Methods Method (A) is used for the determination of TRA and based on condensation reaction of the primary amino group of TRA with salicylaldehyde reagent (SA) (Schiff base formation) producing a yellow coloured product which is measured spectrophotometrically at 400 nm. Method (B) is utilized for the determination of ESL and based on the oxidation-reduction reaction of ESL using iodic acid (HIO3). The liberated iodine was extracted in chloroform and the absorbance of the red coloured product is measured spectrophotometrically at 510 nm. For method A and B, different variables affecting the reactions were studied and optimized. Results: Under the optimum conditions, linear relationships with good correlation coefficients 0.9989 and 0.9959 were found between the absorbance and the concentration of the drug in the range from 5 to 500 and 2.5 to 275 μg mLG 1 for ESL and TRA drugs, respectively. The limit of detection (μg mLG 1 ), limit of quantification (μg mLG 1 ) and molar absorptivity (L molG 1 cmG 1 ) values were found to be 1.442, 4.80 and 5.39×10 2 for TRA drug and 2.20, 7.25 and 3.0×10 2 for ESL drug, respectively. Conclusion: The method was applied for determination of the investigated drugs in tablets. The method was validated and can be suggested for routine analysis of both drugs.