Gunnar Wettermark

An incongruent heat-of-fusion system—CaCl2·6H2O—Made congruent through modification of the chemical composition of the system

An Incongruent Heat-of-Fusion Storage System CaCl2.6H2O Made Congruent through Modifi-cation of the Chemical Composition of the System

A spectroscopic study of the complexation of phthalocyanines with water, ethanol and phenol

Abstract Assignments are collected for the i.r. spectra of solid films of phthalocyanines in their α and β modifications. On the basis of changes in these spectra the ability to form complexes with vapours of water, ethanol and phenol was investigated. All these species were found to be able to form hydrogen bonds to a nitrogen atom in the magnesium phthalocyanine molecule. Only phenol was found to adhere to zinc phthalocyanine but presenting a case of physisorption. There was, however, also signs of an interaction taking place between the zinc compound and water vapour. None of the vapours showed ability to interact with the iron, copper or metal-free phthalocyanine. The iron but not the metal-free compound proved capable of forming a complex, 1: 1, with water in a CCl 4 solution.

A spectroscopic study of complexation of phthalocyanines with pyridine

Abstract The ability of solid films of phthalocyanines to form complexes when exposed to pyridine vapours was investigated on the basis of assignments of i.r. spectra. Pyridine was found to form a five-and a six-coordinated complex with iron and zinc phthalocyanines, respectively, but it did not interact with the copper or metalfree compound. It was, however, physisorbed to magnesium phthalocyanine. In solution iron phthalocyanine proved capable of forming a 1-1 as well as a 1–2 complex with pyridine, both equilibrium constants being 2.10 2 M −1 in CCl 4 . The 1-1 complex appeared instantaneously, whereas the 1–2 complex was formed in a reaction having a rate constant of 0.1 h −1 at room temperature.

Heat-transfer properties of a heat-of-fusion store based on CaCl2·6H2O

Abstract The heat-transfer processes during crystallization and melting of calcium chloride hexahydrate in a heat-storage unit were studied experimentally. The heat transfer through the solid phase is often a limiting factor for the rate of crystallization. For the melting process, convective heat transfer through the melt dominates. For calculating the performance of heat-of-fusion stores, simplified models are developed based on the experimental observations made. An example is given of how the model can be used when dimensioning a storage unit in a solar space-heating system.

Kinetic investigations of reactions between inorganic chlorine compounds and luminol

Abstract The kinetics of chemiluminescent reactions between chlorine (acidic chlorine and alkaline hypochlorite solutions), chlorine dioxide and luminol have been investigated using stopped-flow techniques. The time course of light decay could be properly analyzed using first-order kinetics. The light emission during the analysis of chlorine solutions continued for a considerably longer period of time than during analysis of chlorine dioxide. Acidic chlorine solutions containing extra chloride produced two different luminescent profiles. The results have been interpreted as indicating that the active species in chlorine solutions which react with luminol are HClO and Cl 2 (aq).

Selective Analysis of Chlorine (Hypochlorous Acid) and Chlorine Dioxide Using Chemiluminescence

Abstract Using chemiluminescence produced by reactions with luminol and hydrogen peroxide a method for simultaneous and selective analysis of chlorine (hypochlorous acid) and chlorine dioxide has been developed. A continuous flow technique is used and the light emitted at two sites along the liquid flow is recorded. Selectivity is based on the difference in the rates at which the chemiluminescence, produced by the reaction involving chlorine and that involve chlorine dioxide, fades.

Preparation, spectroscopic assignments and relative stabilities of cis and trans species of o,o′-azodioxytoluene in the solid state and in solution

Abstract Crystalline samples of cis- and of trans-o,o′-azodioxytoluene have been isolated. The cis crystals isomerize spontaneously to trans. IR spectra were recorded for the pure dimeric species as well as for o-nitrosotoluene and assignments of specific peaks were made. In solution the cis form is the energetically more stable species as revealed from NMR assignments on cis and trans samples.

Determination of the equilibrium constants and UV-absorption spectra for Cu2+Cl− complexes in 1 M HClO4

The complex constants for the Cu(II)-chloride complexes CuCl+ and CuCl2 have been determined spectrophotometrically at 25°C and in 1 M HClO4. The evaluation procedure employed was a regression anal ...

Optical properties of metallic copper in relation to the photochromic system CuCl(s)H2O(l)

An extended Mie theory has been used to interpret the green colour change observed in the photochemical disproportionation of CuCl. Comparison of calculated and experimental spectra leads to the following conclusions: (i) the green colour arises from colloidal metallic copper in CuCl present in low concentrations (<5 vol %); (ii) the colloid consists of particles with an average diameter of about 3 nm in diameter and probably oblate in shape with an axis ratio of about 0.6; (iii) under the conditions of the present experiment the spectrum of the green species stayed constant, i.e. continued exposure has primarily the effect of increasing the number of copper particles without affecting their size and shape.

The photochemical disproportionation reaction in the system CuCl(s)-H2O(l)

Abstract The photochemical production of Cu0 in the system CuCl(s)—H2O(l) was investigated using reflectance spectoscopy. For u.v. light activation the spectral sensitivity follows the excitonic absorption band of CuCl. The system may also be activated with visible light (after an induction period) through a sensitized process with the photoproduct Cu0 as the sensitizer. The experimental data, including the time-course of the reaction, are consistant with the following mechanism: Cu0 aggregates are formed close to the phase boundary. Continued exposure increases the depth of the Cu0 containing layer but the local concentration of Cu0 stays essentially constant. With u.v. light there is a continued increase in the number of Cu0 aggregates but visible light activation has in addition the effect of enlarging the aggregates. As the depth of the layer increases the reaction is slowed down due to an inner filter effect from Cu0; the Hurter equation, usually employed to characterize the photographic process in silver halide systems, is obeyed.