Kratschmer-Huffman conditions

The dicyanopolyacetylenes 14-18, which are also of importance in connection with interstellar chemistry and novel forms of carbon, have been obtained very recently by vaporizing graphite in the presence of cyanogen under Kratschmer-Huffman conditions [21]. The polyyne fraction obtained consisted of 55% 14, 35% 15 and 10% of the higher homologs 16-18 as analyzed by HPLC. Cyanocarbon 14 has been obtained in analytically pure form as expected, it is only stable in dilute solution under occlusion of light and moisture at low temperatures [21]. 

From the synthetic point of view this is a representative of a remarkable family of metal nitride endohedrals, AXB3 XN C80 (x=0-3), which, under the right conditions, can become the main product in the Kratschmer-Huffman carbon arc-based synthesis, rather than being present at low level as a by-product of C60 and C70 synthesis [6,38]. 

It was only in 1990 when the groups of W. Kratschmer and D. R. Huffman succeeded in isolating macroscopic amounts of the most abundant fuUerene C o by the arc evaporation of graphite or by resistance heating of graphite electrodes, respectively. In fact, their initial intention, too had been to produce in the laboratory substances that exist in interstellar dust, but at suitable conditions, their IR-spectra exhibited four sharp, characteristic signals that related to those predicted for the Ceo-molecule. Later on, C70 and the higher fullerenes were also obtained. 

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