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• 3264-21-9 1-acetylpyrene 

Relevant academic research and scientific papers

Synthesis and stable-ion studies of regioisomeric acetylnitropyrenes and nitropyrenyl carbinols and GIAO-DFT study of nitro substituent effects on α-pyrenyl carbocations

Several regioisomeric acetylnitropyrenes were synthesized from isomeric acetylpyrenes by mild protic nitration. Nitration of 1-acetylpyrene gave the 3-, 6-, and 8-nitro derivatives (with 8-nitro as the major isomer), from which the corresponding carbinols [NO2-Py-CH(OH)CH3; Py = pyrene] were synthesized. Isomeric 4-acetylnitropyrenes and their corresponding carbinols were synthesized by starting from hexahydropyrene through nitration/aromatization/reduction or aromatization/nitration/reduction sequences. The molecular structures of 4-acetyl-3-nitropyrene and 1-(6-nitropyren-1-yl) ethanol were established by X-ray analysis. Tetrahydropyrene was the starting point for the synthesis of isomeric nitro-2-acetylpyrenes. Low-temperature protonation of 1-acetyl-8-nitropyrene, 4-acetyl-3-nitropyrene, and 2-acetyl-6-nitropyrene in FSO3H/SO 2ClF or in FSO3H/SbF5 (1:1)/SO2ClF resulted in the formation of onium dications (by C=O and NO2 protonation). Charge delocalization (pyrenium ion character) in the carboxonium ions is strongly influenced by the position of the carboxonium group, with the 4-acetyl-3-nitropyrene dication being the most delocalized. Superacid protonation of 1-(3-nitropyren-4-yl)ethanol gave a persistent onium dication rather than an α-pyrenyl carbocation. With all other isolated nitropyrenyl carbinol isomers, low-temperature protonation (with FSO3H/SO 2ClF) led to polymerization within 5 min standing at dry-ice-acetone temperature. For these cases, nitro substituent effects on the α-pyrenyl carbocations were gauged by DFT and GIAO-DFT studies. An interesting relationship between the computed nitro tilt angles and the GIAO-derived charge delocalization modes was observed. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.