Yu. G. Ponomareva

Water-soluble polyketones and esters as the main stable products of ozonolysis of fullerene C60 solutions

Stable ozonolysis products of C60 solutions in CCl4, toluene, and hexane were studied by elemental analysis, HPLC, and UV and IR spectroscopy. Polyketones and esters were established for the first time to be the main stable products, whose content increased during the whole ozonolysis time (1 h). Epoxides C60On (n = 1—6) are accumulated within 1—3 min, and after 5 min of ozonolysis their concentration decreases to zero. Fullerene C60 disappears from the reaction solution due to its conversion to oxides and mechanical capturing of C60 by these oxides to form a precipitate. The oxidation of C60 is completed in the solid phase by the formation of the C60O16 oxide in which 9.68 O atoms fall on fullerene polyketones, 6 O atoms are attributed to esters, and 0.32 O atoms fall per epoxides. The optimum medium for preparation of the C60 oxides is CCl4 rather than traditional toluene, which reacts with ozone in the side reaction to form products containing active oxygen. The C60 cage is raptured during ozonolysis because of the C=C bond cleavage to form two C=O groups at the ends of the open hexagon. Ozonolysis of C60 solutions in CCl4 is efficient for synthesis of water-soluble fullerene oxides due to the high yield and solubility of polyketones and esters in water.

Kinetics and stoichiometry of the reaction between ozone and C70 fullerene in CCl4

The kinetics and stoichiometry of the reaction between C70 fullerene and ozone have been studied. The reaction obeys a bimolecular rate law. The stoichiometric coefficients of the reaction are 1: 12 to 1: 22, depending on reaction conditions. The rate constant at 22°C is 5 × 104 l mol−1 s−1 for the first stage of fullerene conversion and (0.8–0.6) × 104 l mol−1 s−1 for the subsequent stages. Since the stages differ in terms of reaction rate, the original C70 molecules are first involved in the reaction, whereas, at the subsequent stages, all molecules are involved with equal probabilities, irrespective of the number of preceding reaction events in which they have participated.