Pressure effect on heterogeneous trifluoromethylation of fullerenes and its application

The first systematic study of heterogeneous fullerene trifluoromethylation using an innovative gradient-temperature gas–solid reactor revealed a significant effect of CF3I pressure on the conversion of C60 and C70 into trifluoromethylated products and on the range of fullerene(CF3)n compositions that were obtained. The design of the reactor allowed us to lower the residence times of fullerene(CF3)n species in the hot zone which resulted in the significant differences in relative isomeric distributions as compared to the earlier methods. For the first time, gram quantities of trifluoromethylated fullerenes were prepared using the new reactor, and the selective synthesis of a single-isomer C60(CF3)2 was developed. The relative reactivity of C70 as a CF3 radical scavenger was found to be much lower than that of C60, especially at an early radical addition stage, which led to the cost-efficient synthesis of C60(CF3)2 from a fullerene extract.

The first systematic study of heterogeneous fullerene trifluoromethylation using an innovative gradient-temperature gas–solid reactor revealed a significant effect of CF3I pressure on the conversion and on the range of fullerene(CF3)n compositions. The selective synthesis of a single-isomer C60(CF3)2 was developed.Figure optionsDownload as PowerPoint slideHighlights
► Significant improvements in understanding of heterogeneous trifluoromethylation of fullerenes.
► Preparation of trifluoromethylated fullerenes in hundreds of mg.
► Effect of gas pressure has been studied using an original gradient-temperature-gas–solid reactor.
► Selective preparation of bis-trifluoromethylated C60, using “low-conversion regime”, including an economical method with the use of inexpensive fullerene extract.
► We discovered that C70 has much lower reactivity towards CF3 radical addition than C60.