The solubilities of flavone and 3-hydroxyflavone in supercritical carbon dioxide (SC-CO2) were measured at 308.2 K and 318.2 K over the pressure range from 9.1 MPa to 25.3 MPa by a flow type apparatus, which can detect the concentrations of the solutes in a supercritical fluid. The solubilities were determined from the mass of solute trapped by decompressing and the volume of CO2. Solubility data were correlated by a solution model based on the regular solution model.

The process of the first-order solid-to-solid phase transition of 1-ethyl-3-(4-methylpentanoyl)urea (1) was observed by means of a detailed temperature-resolved single-crystal diffraction method, which resembles watching a series of stop-motion photographs. The transition consists of two elementary processes, one supramolecular and the other molecular. Crystal structures from before and after the phase transition are isostructural. The straight-ribbon-like one-dimensional hydrogen-bonding structure is formed and stacked to form a molecular layer. The geometry of the layer is retained during the phase transition. The relative position of the layer with its neighbours, on the other hand, changes gradually with increasing temperature. The change is accelerated at the temperature representing the start of the endotherm seen in the DSC curves of (1). The structural variation yields void space between the neighbouring layers. When the void space grows enough that the crystal is unstable, the 3-methylbutyl group on the last of the molecules turns into a disordered structure with drastic conformational changes to fill up the void space. The phase transition process is well supported with simple force-field calculations. A crystal of 1-(4-methylpentanoyl)-3-propylurea (2), which shows no solid-to-solid phase transitions, was also analysed by the same method for comparison.

This paper proposes a method for electroless plating by combining supercritical fluid technology and electroless plating in a hybrid technique. The electroless plating reactions are carried out in an emulsion of supercritical carbon dioxide and an electroless plating solution with surfactant. The Ni-P film obtained by this proposed technique was a uniform and conformal film without the pinholes that form from the hydrogen bubbles produced by the electrolysis of water, and without the nodules that form from the nuclear growth on the electroless plating reaction. The dissolution of the hydrogen bubbles in the dense CO 2 particles of the emulsion prevented the pinholes from forming. The formation of nodules might have been prevented by the transport properties of the emulsion with the diffusive dense CO 2 and the suppression of the dissolved oxygen concentration when the oxygen dissolved in the dense CO 2 particles of the emulsion. The Ni-P film fabricated by our technique was smoother and more uniform than the substrate. The roughness of the plated film was constant during film growth, whereas the surface of the film fabricated by conventional electroless plating tended to roughen as the reaction time increased.

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