Protonation and sulfinylation of isomeric isopropylpyrenes, 2,7-di-tert-butylpyrene, and tetracyclohexyl- and tetracyclopentylpyrenes: remarkably stable, sterically crowded pyrenium cations
摘要:
1-Isopropyl- (1), 2-isopropyl- (2), 4-isopropyl- (3), 1,3,6,8-tetraisopropyl- (4), and 1,3,5,7,9-pentaisopropylpyrene (5), 2,7-di-tert-butylpyrene (6), and 1,3,5,8-tetracyclohexyl- (7) and 2,4,7,9-tetracyclopentylpyrene (8) in FSO3H or CF3SO3H (TfOH) in SO2 or SO2ClF solvent gave stable monopyrenium ions. In agreement with theory, exclusive alpha protonation occurred at low temperature (-75 --> -65-degrees-C) irrespective of the position of the substituents. The position of alpha-protonation is controlled by inductive stabilization of the alkyl (cycloalkyl) groups. Unlike hexahydropyrene which is diprotonated in FSO3H.SbF5 (1:1) Magic acid, with isopropylpyrenes stable dications could not be generated; in SO2 solvent the Wheland intermediates of sulfinylation were observed, whereas in SO2ClF solvent oxidation and monoprotonation were competitive. Charge distribution patterns in the sulfinylation sigma-complexes are similar to those of protonated pyrenium ions. Stable pyrenium cations deprotonate or desulfinylate on quenching without dealkylation or disproportionation. At higher temperatures (ca. -40-degrees-C), ipso-protonated 4 undergoes isomerization in FSO3H/SO2 solvent; other alkyl (cycloalkyl)pyrenium cations show no isomerization/disproportionation. Upon standing in Magic Acid, hexahydropyrene is oxidized to pyrene.
METHOD FOR PRODUCING ARENE COMPOUNDS AND ARENE COMPOUNDS PRODUCED BY THE SAME
申请人:JSI Silicone Co.
公开号:US20210188739A1
公开(公告)日:2021-06-24
Provided is a method for producing (alkyl)arene compounds represented by Formulae 3-1, 3-2, and 3-3 by the Friedel-Crafts alkylation reaction of alkyl halide compounds and arene compounds using organic phosphine compounds as a catalyst.
Berg, Arne; Lam, Joergen; Hansen, Poul Erik, Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry, 1986, vol. 40, # 8, p. 665 - 677
作者:Berg, Arne、Lam, Joergen、Hansen, Poul Erik
DOI:——
日期:——
Nitration of isopropylpyrenes. Strained models for protonation and transfer-nitration in the condensed phase
作者:Kenneth Khosrow Laali、Tze Ming Liang、Poul Erik Hansen
DOI:10.1021/jo00035a022
日期:1992.4
Protic mono- and dinitration of 1,3,5,7,9-pentaisopropylpyrene (1) occurred at the available alpha positions to give 2 and 3. Despite steric crowding, 2 and 3 did not exhibit a torsional barrier to i-Pr rotation at ambient temperatures; however, buttressing of the peri i-Pr groups was evident (H-1 NMR, UV, and force field energy minimizations). Persistent (dihydroxyiminium)pyrenium dications 2a+2 and 3a+2 were formed by low temperature protonation of 2 and 3 with CF3SO3H (TfOH)/SO2 or with FSO3H/SO2. Intramolecular cyclization of the nitro group of 2a+2 gave the rearranged pyrenium ion 2c+. 1 reacted with NO2+BF4- in acetonitrile solvent to give two pyrenium ions stable at rt, viz. the Wheland intermediate of alpha-nitration 2b+2 and the (dihydroxyiminium)pyrenium dication 2a+2; the latter was also the predominant pyrenium ion formed in the reaction of 1 with NO+BF4- in acetonitrile. Reaction of 1 with NO2+BF4- in chloroform solvent gave alpha-nitration products and a persistent radical cation RC. The simultaneous presence of alpha-nitration products and a persistent pyrenium RC was also observed in the reaction of 1 with NO+BF4- in chloroform, where broader NMR line widths and a stronger ESR signal suggested more extensive oxidation. Protic and aprotic nitrations of 1,3,6,8-tetraisopropylpyrene (10) occurred at the alpha-beta positions; a minor addition product (26) was also found. A mixture of isomeric dinitropyrenes was obtained in NO2+ nitration of 1-isopropylpyrene (13). In line with low temperature protonation studies, aprotic nitrations of 2-isopropyl- and 4-isopropylpyrenes occurred predominantly at the alpha positions. The crowded pyrenium ion of 3 and 2 transfer nitrate to aromatics (toluene, mesitylene, benzene) under mild conditions in competition with a more facile transalkylation.
BERG A.; LAM J.; HANSEN P. E., ACTA CHEM. SCAND., 40,(1986) N 8, 665-677