Mihály T. Beck

Solubility of C60

Abstract All the published data on the solubility of C60 in 140 organic and inorganic solvents are summarized and the critical features of the experimental techniques are treated. Data on die temperature dependence of solubility are also listed and analyzed. Experimental evidences on the molecular state of dissolved C60 as well as the interactions between the solute and solvents are discussed.

Homogeneous hydrogenations in aqueous solution catalyzed by ruthenium-phospine complexes

Abstract By unsing m -sulphophenyl-diphenylphosphine (mSPo 2 ) several ruthenium(II)-phosphine complexes were prepared and characterized. The complexes RuCl 2 (mSPo 2 ) 2 , HRuCl(mSPo 2 ) 3 , HRu(OAc)(mSPo 2 ) 3 and HRuCl(CO)(mSPo 2 Z) 3 are readily soluble in water, while the dicarbonyls, cis and trans -RuCl 2 (CO) 2 (mSPo 2 ) 2 and cis -HRuCl(CO) 2 (mSPo 2 ) 2 are water-insoluble. RuCl 2 (mSPo 2 ) 2 , HRuCl(mSPo 2 ) 3 andRu(OAc)(mSPo 2 ) 3 catalyze the hydrogenation of several C, O- and C, C-unsaturated compounds in aqueous solutions, at 20−10 °C and atmospheric hydrogen pressure. Detailed kinetic studies were made on the hydrogenation of crotonic and pyruvic acids. The results show an interesting selectivity, namely that the hydrogenation of pyruvic acid is catalyzed only by the trisphophine species, HRuX(mSPo 2 ) 3 (X − = Cl − orAcO − , while the hydrogenation of crotonic acid is catalyzed exclusively by the gisphosphine derivatives, HRuX(mSPo 2 ) 2 ·(HRuCl(mSPo 2 ) 2 may be prepared from RuCl 2 (mSPo 2 ) 2 and H 2 , while HRu(OAc)(mSPo 2 ) 2 arises from the dissociation of HRu(OAc)(mSPo 2 ) 3 . This selectivity is a consequence of the different binding of the two types of substrates in the catalytically active intermeideates. These complexes catalyze also the two-phase hydorgenation of hex-1-ene and styrene.

SOLUBILITY AND MOLECULAR STATE OF C60 AND C70 IN SOLVENTS AND SOLVENT MIXTURES

The solubility of C, and has been studied very thoroughly. Beside the obvious practical importance, there is a great theoretical interest in the determination and explanation of the solubility data. The anomalous dependence of solubility on temperature is due to the formation of solid solvates and interaction between the fullerenes and solvents leading to the formation of a series of well defined complexes. One always should consider the possibility of colloid formation, particularly when sonication is applied to enhance the rate of dissolution. Sonication offers a possibility to achieve higher concentration of dissolved fullerenes. However, prolonged sonication may result in a decrease of concentration.

Rhodium(I) and ruthenium(II) complexes of sulphonated triphenylphosphine immobilized on ion-exchange materials

Abstract Complexes of sulphonated triphenylphosphine with Ru(II) and Rh(I) were immobilized on strongly basic anion exchangers. The heterogenized complexes were successfully applied to the hydrogenation of various olefins in solution and in the gas phase, at 60 °C and 120 °C, respectively, and 0.1 MPa total pressure. Kinetic features of crotonic acid hydrogenation in aqueous solution suggest that the anchored RuCl 2 ( m -SPφ 2 ) 2 exerts its catalytic influence via the same molecular pathway as in homogeneous solutions

Formation of C60 and polycyclic aromatic hydrocarbons upon electric discharges in liquid toluene

Abstract A great number of polycyclic aromatic hydrocarbons and C60 are formed upon the effect of electric discharges in liquid toluene between graphite or pyrographite electrodes applying high voltage AC.

Kinetics of the photoaquation of Hexacyanoferrate(II) ion

Abstract Kinetics of the photoaquation of hexacyanoferrate(II) ion in aqueous solution were studied potentiometrically and spectrophotometrically. Supposing the simplest mechanism (see Fig. 3. in text), the photoaquation in alkaline medium can be well described. The value of the constants at pH = ll.0 are: o = 0.8-1.0, k 6 = (3.0 ± 0.5) × 10 −8 s −1 and k −6 = 1.5 ± 0.2 mol −1 dm 3 s −1 . To describe the photoaquation in neutral medium t was extended ( k ′ = 3.33 x 10 2 mol −1 dm 3 s −1 ). The quantum yield in acidic medium can be calculated by combination of o values of different protonated complexes. The reversibility of photoaquation in alkaline medium is also explained by the scheme.

Formation of polycyclic aromatic compounds upon electric discharges in liquid toluene

Abstract The formation of a great number of polycyclic aromatic compounds up to 604 mass number occurs when electric discharges are made in liquid toluene with one or both electrodes being graphite.

Oxidation of thiourea by iodate: a new type of oligo-oscillatory reaction

In the oxidation of thiourea by iodate in weakly acidic solution the concentration of iodide may exhibit several extrema. The number of extrema mainly depends on the initial ratio of the concentrations of thiourea and iodate, and is at most four. The first step of the reaction results in the formation of iodide which then reacts with iodate to give iodine. The latter oxidizes thiourea in several steps, the end products being sulphate ions, ammonium ions, and carbon dioxide. Taking into account the independently determined rate constants for the sub-systems, the change in the concentrations of iodide and iodine with time can be calculated. There is good agreement between the experimental and theoretical curves.

Diagrams for complete representation of binary mononuclear complex systems

Solution equilibria are calculated from the system of equations expressing the mass balance and the law of mass action. The solution of these equations usually requires the use of complicated iterative procedures. It is shown in the present paper, that for mononuclear complex formation, the whole system can be represented by a single diagram exhibiting all of the important chemical information, including solubility equilibria. The data necessary for the construction of the diagrams can be calculated directly without iterative procedures.

Inhibition of a homogeneous periodic reaction by radical scavengers

The periodic reaction between malonic acid, sulphuric acid, potassium bromate, and a catalyst is inhibited by molecular oxygen, hydrogen peroxide, and acrylonitrile, and hence has a free-radical mechanism.