Polymerization of acetylene: polyynes, but not carbyne‡

The formation of polyynes via polymerization of acetylene gas and endcapping with the tris(3,5-di-t-butylphenyl)methyl moiety (Tr*, supertrityl) has been explored. The polymerization process has been optimized based on the length of the polyyne endcapping groups. Separation-purification-identification has been achieved through reversed-phase (RP) high performance liquid chromatography (HPLC), utilizing UV-vis detection, which offers UV-vis spectra of the polyyne products. The chain length of individual polyynes can then be established through comparison to the spectra trends of known polyyne samples. LDI and MALDI mass spectrometry is used to examine the presence of Tr*[n] polyynes in the crude reaction mixture. The combined analyses show that polymerization reactions of acetylene using the supertrityl endgroup allow formation of polyynes, but much shorter than could be achieved by stepwise syntheses.