CaI2 Research Articles

The calcium-iodine cycle for the thermochemical decomposition of water

A new four-step thermochemical cycle based on calcium and iodine is proposed for the decomposition of water. The chemical reactions comprising the cycle are: the redox reaction of iodine with calcium hydroxide; the thermal decomposition of calcium iodate; the hydrolysis of calcium iodide; and the thermal decomposition of hydrogen iodide. Experimental verification of each of these reactions and an evaluation of the thermal efficiency of the process based on the material and energy balances for a proposed flow sheet are also presented.

Investigation of dehydration process, II

The dehydration of hydrated calcium and strontium bromides and iodides was studied by thermogravimetry and differential thermal analysis. The melting in the crystallization water was distinguished from the dehydration in a self-generated atmosphere. The results of the TG and DTA curves made simultaneously were verified by measurements with a Du Pont DSC apparatus. This latter investigation was extended to the previously studied chlorides too. Correlations were found between the temperature of melting or of dehydration and the ionic radii of the respective cations and anions.

Formation of the second layer of krypton on the cleavage face of calcium iodide; Further evidence of the importance of entropy in physisorption

From the analysis of a set of stepped adsorption isotherms of krypton on the cleavage face of calcium iodide, it is concluded that, above 70.5 K, a second adsorbed monolayer is formed, having an apparent molar energy (algebraic value) and entropy higher than those of the bulk phase of the adsorbate. The differences in energy and entropy are exceptionally high for a second layer, and consequently, when the temperature is lowered below 70.5 K, the pressure corresponding to the second step becomes higher than the sublimation pressure and the step disappears. This unusual observation of a second dense monolayer existing only because of its high entropy, again emphasizes the fundamental importance of entropy in physical adsorption. It is secondarily noted that the isotherms present evidence of interparticle condensation occurring at high relative pressures.

Synthesis and some reactions of bis(triphenylstannyl)carbodiimide, N′-(triphenylstannyl)- N′-tritylcarbodiimide, and (triphenylstannyl)cyanamide

Some methods for preparing bis(triphenylstannyl)carbodiimide (I), N-(triphenylstannyl)- N′-tritylcarbodiimide (II), and (triphenylstannyl)cyanamide are described. (I) was found to react with 1,3-disubstituted thioureas in refluxing acetonitrile or toluene to give bis(triphenyltin) sulfide and the corresponding N,N′-disubstituted- N″-cyanoguanidine. Some evidence for a diorganocarbodiimide intermediate in this reaction was found. The reaction of(I) with thiourea in refluxing acetonitrile was found to give bis(triphenyltin) sulfide,(triphenylstannyl)cyanamide and unchanged thiourea. The reaction of (I) with cyanamide gave (triphenylstannyl)cyanamide. (Triphenylstannyl)cyanamide was found to react with bis(triphenyltin) oxide in refluxing acetonitrile to give (I). (Triphenylstannyl)cyanamide was found to disproportionate in refluxing benzene to give (I) and dicyandiamide. (II) was found to be more hydrolytically stable than (I). The SnN bonds in both (I) and (II) were found to be readily cleaved by acetic acid. It was found that triphenyltin iodide and triphenyltin chloride can be conveniently prepared in good yield by the reaction of bis(triphenyltin) oxide with either calcium iodide or calcium chloride in refiuxing acetonitrile.

Ionic Conduction in Calcium Doped Polycrystalline Lithium Iodide

The ionic conductivity of polycrystalline lithium iodide containing 0 to 3% (mole) calcium iodide was studied at temperatures between −30° and 130°C.The conductivity increased linearly with the concentration of calcium iodide, and it was concluded that the introduction of calcium ions to the lithium iodide crystals induced Schottky defects. The activation energy for the ionic conduction process of agreed well with the value obtained by other investigators. The electronic conductivity of the calcium doped lithium iodide polycrystals was negligible compared to the ionic conductivity.

Cleavage of β-ketonic esters by the action of metal iodides. II. Action of hydrate sodium and calcium iodides on acetoacetic ester and its α-methylated derivatives

Cleavage of β-ketonic esters by the action of metal iodides. II. Action of hydrate sodium and calcium iodides on acetoacetic ester and its α-methylated derivatives

Role of calcium in contractile excitation of vascular smooth muscle by epinephrine and potassium.

A technique of constant-flow perfusion of isolated segments of dog intestinal arteries was used to investigate the role of calcium in contractile excitation of vascular smooth muscle by epinephrine and potassium. Contractile responses of the arterial muscle to epinephrine, perfused at constant concentration, and to potassium, perfused at high concentration, were both promptly prevented by calcium deionizing accomplished by simultaneous perfusion with solutions containing ethylenediaminetetraacetate (EDTA) for the chelation of available calcium ions. Potassium-induced muscular contracture was removed in a few minutes and epinephrine-induced contractions of potassium-depolarized muscle were soon prevented by perfusion with solutions containing ionic species of EDTA which chelated calcium ions. In muscle depolarized by potassium and calcium deionized by perfusion with solution containing MgK 2 EDTA, the contractile responses to epinephrine were immediately restored by combined perfusate injection of calcium ion and epinephrine. Injections of isosmotic calcium chloride solution of subthreshold or threshold contractile strength, when the artery had been perfused with sodium chloride-rich solution and the muscle had been relaxed, produced much greater contractions during both potassium and epinephrine excitation. The contractions from injected calcium chloride solution were increased by epinephrine excitation of muscle already depolarized by the external application of potassium sulfate, as they were in the previously polarized or resting muscle excited by epinephrine. The thesis is advanced that the relative muscular contractions induced by standard injected volumes of isosmotic calcium chloride solution were a relative index of the calcium influx and calcium permeability of the arterial smooth muscle cells in the various experimental conditions prevailing. Equimolar injections of isosmotic calcium iodide solution produced greater muscular contractions than did injections of isosmotic calcium chloride solution. The possibility is discussed that transmembranous passage of calcium into vascular muscle cells occurs significantly in the form of associated ion pairs. A dual effect of potassium on vascular smooth muscle behavior was observed in that a previously contractile-inducing amount of injected potassium exerted a relaxing effect on the arterial segment perfused with low-potassium solution when the muscle was contracted by epinephrine. It is concluded that: (a) calcium is essentially involved in excitation-contraction coupling of vascular smooth muscle; (b) the calcium permeability and calcium influx of vascular smooth muscle is greatly increased during both epinephrine and potassium excitation of the muscle cells, and epinephrine accomplishes these calcium changes even in muscle already depolarized by potassium; (c) adrenergic neurohormones exert their vasoexcitatory contractile effect by a membrane reaction which is basically nonelectrical and which primarily triggers an increased permeability and influx of calcium into the vascular myoplasm; and (d) the migrated calcium activates intracellularly the myoplasmic events of vascular smooth muscle contraction.

Ultrasonic Velocity in Aqueous Solutions of Some Electrolytes

WHILE carrying out investigations in a number of aqueous solutions of electrolytes, we have observed the interesting feature of a decrease of ultrasonic velocity with increase of concentration in the case of aqueous solutions of calcium iodide, zinc bromide, silver nitrate and cerous acetate, contrary to the normal type of behaviour exhibited in general by electrolytes. Velocity measurements in the above solutions of electrolytes at 30° C. were carried out using a fixed-path, variable frequency interferometer1, at a frequency of 1.5 Mc./sec. The accuracy of the measurements is ± 1 m./sec. The variation of density with concentration in all the above cases is found to be linear.

The Concentration of I131 in the Bronchial Tree after Oral Administration of Tagged CaI2 and KI

A group of 12 patients having various bronchopulmonary diseases for which repeated bronchoscopy was indicated were given orally 5 ml. of aqueous solution containing radioactive calcium iodide and two weeks later the same group of patients received 5 ml. of solution containing an equal dose of iodine in the form of radioactive potassium iodide. The concentration of radioactive iodine in bronchial samples, the total urinary drug excretion, and the thyroid uptake were determined following the administration of radioactive iodine in each of the two forms. In each instance, the excretion in detectable amounts in bronchial aspirates was found at a 15 minute period following administration. The excretion appeared to continue for a period of four hours on the basis of the continued detectability of radio-iodine in aspirates at that time. The highest level of concentration of radioactive iodine was found at an interval of 30 minutes after administration of each drug. Throughout the period of study a higher concentration in bronchial secretion was found after the administration of calcium iodide than after the administration of potassium iodide. Total urinary drug excretion and thyroid uptake during the first 24 hours following the administration was not different following administration of the two drugs. These studies suggest that calcium iodide administered orally results in a rate of bronchial secretion greater than that which follows the administration of potassium iodide. Calcium iodide may be a preferable expectorant drug on this basis, even apart from the possible dangers of the administration of potassium salt for the same purpose.

Low‐Temperature Electrolytes: Study of Some Physical Properties of the Calcium Halide‐Water Systems over the Temperature Range of 25° to −60° C

Data are given for electrical conductivity, freezing points, density, and viscosity of several solutions of calcium chloride, bromide, and iodide over the temperature range of 25° to −60°C. Halide solutions have the following eutectics: calcium chloride, −55°; calcium bromide, −83°; and calcium iodide, −77°C. The calcium iodide‐water system has an incongruent melting point at −23.5°C. The electrical conductance‐viscosity product shows considerable deviation from Walden's rule.

SYNTHESIS OF ORGANIC DEUTERIUM COMPOUNDS: X. METHYL-d3 IODIDE AND DEUTERIUM SUBSTITUTION PRODUCTS OF METHYL ACETATE

Methyl-d3 bromide was easily converted by treatment with calcium iodide into methyl-d3 iodide in 94% yield. The latter was reacted on the 50-millimole scale with silver acetate or silver acetate-d3 to yield methyl-d3 acetate or methyl-d3 acetate-d3. Methyl iodide and silver acetate-d3 gave methyl acetate-d3.

Relation of chemical structure to activity of iodine compounds against the developmental stages of horse strongyles

In a study of the toxicity of 43 iodine compounds for the developmental stages of horse strongyles in feces, compounds which were lethal at a concentration of 0.0005 M or less were iodic acid, periodic acid, barium iodide, cadmium iodide, calcium iodide, lithium iodide, plumbous iodide, strontium iodide, zinc iodide, trimethylene iodide, and pentamethylene iodide. In a series of 16 alkyl monoiodides, all n-alkyl iodides with five or less carbon atoms were inactive at a concentration of 0.01 M. The most toxic member of the series was n-octyl iodide (0.0025 M). Compounds with more carbon atoms were increasingly less active. The three alpha-omega diiodides, ethylene iodide, trimethylene iodide and pentamethylene iodide, were much more active than their related n-alkyl monoiodides. In an analysis of the results obtained in this and a previous study, it has been shown that the toxicity of the compounds is closely related to the availability of the iodine atom. Those compounds in which it is ionized as an iodide ion (inorganic ionized compounds, quaternary ammonium iodides, quaternary heterocyclic nitrogen iodides, and iodonium iodides) were highly toxic, while inorganic un-ionized compounds, aryl iodides and polyiodo compounds, in which the iodine is tightly bound, were relatively non-toxic. Alkyl iodides, in which the iodine is less tightly bound, were intermediate in toxicity. Alpha-iodo and beta-iodo carbonyl compounds, in which the iodine is still more loosely bound, were as toxic as the ionized compounds.

Calcium Metal

ELECTROMETALLURGY has at last succeeded in producing metallic calcium in commercial quantities, and at what must be considered a relatively low price. Until within a few weeks ago this metal had only been available in very small amounts, and remained a rare laboratory specimen; it is now obtainable at a price per kilogram less than that charged by most chemical dealers for a small one-gram sample. Humphry Davy first formed the amalgam by electrolysing lime, mixed with mercuric oxide and slightly moistened, with a mercury kathode; he isolated the metal in small quantities by distilling off the mercury. Since then many chemists have tried in vain to find a method suitable for its preparation on a larger scale. Matthiesen, making use of Bunsen's suggestion of applying high current density at the kathode, only succeeded in obtaining a fewT grams at a time by electrolysis of the fused chloride, or of mixtures of calcium and other chlorides having a lower fusing point. Henri Moissan, as the result of a critical study of the numerous proposed methods, was able to prepare somewhat larger quantities of the metal. His method was essentially a modification of that proposed by Lies-Bodart and Jobin in 1858, which consisted in reducing fused calcium iodide with metallic sodium. Moissan found that molten sodium forms an excellent solvent for calcium, and by heating calcium iodide with a large excess of sodium obtained on cooling a cake of the sodium-calcium alloy resting on the sodium iodide. Small quantities of the alloy were thrown into well cooled absolute alcohol, which reacts with the sodium leaving the calcium pure, but in the state of a fine crystalline powder. This powder can be agglomerated by pressure and fusion, and thus Moissan prepared the fine specimen ingots of this metal which so greatly interested visitors to the Paris Exhibition of 1900. It is largely to him that we are indebted for a knowledge of the properties of the pure metal, of which he prepared some 4. kilos, by this process. Contrary to the earlier descriptions, calcium is a white metal, the yellow coloration being due to a film of nitride; its melting point is about 760° C, and its density 1.85. The definite compounds which it forms directly with hydrogen and nitrogen promise useful applications in the laboratory in cases where it is necessary to remove these gases.

To the casuistry of iodism. Thyreoiditis acuta

A person suffering from syphilis has been prescribed calcium iodide (Sol. e. 4.0-180.0 4 times a day with a tablespoon) during the course. In the evening of the same day, after taking the 3rd spoon of the medicine, a patient with a still feeling well had a fever of 39R, a terrible runny nose and severe swallowing pain.