¹H NMR and ¹³C NMR spectroscopy of pyrene dianions

Abstract

Abstract.A simple technique for the preparation of anions of polycyclic aromatic hydrocarbons is described. 'H and I3C NMR spectra of dianions of pyrene and derivatives of pyrene are reported and discussed. The electron density is greatest at the carbon atoms in the perimeter of the dianions. The presence of an electron-donating substituent at position2 causes an increase in the charge at positions 1 and 3.

Synthesis of substituted pyrenes by indirect methods

“…For example, 2-nitroTHPy 14 has also been prepared by treatment of THPy with dinitrogen tetraoxide, 62 or with nitrate salts in acetic or trifluoroacetic anhydride. 49,51,54,55,58 The early work of Bolton had a large impact on subsequent synthetic work with pyrene, since some of the compounds initially described by this author have served as intermediates for a variety of subsequent pyrene derivatives (Schemes 7-10).…”

“…55 Birch conditions with lithium reductant have also been used by some workers. [56][57][58] Again, purification of commercial pyrene prior to the reaction seems to be essential for the reaction to be successful. The Birch reduction does not give directly the desired compound but the intermediate 4,5-dihydropyrene (DHPy), which can be subsequently hydrogenated in the presence of Pd/C to yield the desired THPy in good yields.…”

“…A second reduction with sodium in xylene-ethanol yields a mixture of THPy and HHPy, from which THPy may be isolated after selective nitration of the latter. 58 It is also possible to synthesise THPy via ring closure of [2,2]metacyclophane or photo-chemical cyclisation of 2,2′-divinylbiphenyl. These approaches are discussed further in sections 5 and 6.…”

“…61 2-MethoxyTHPy 25 has also been prepared from compound 19 by using Baeyer-Villiger oxidation conditions, 47 or from 2-aminoTHPy 18 via a diazonium salt. 58 Haloform oxidation of 19 leads to the corresponding acid 26, which can be transformed into 7-amino-2-pyrenylcarboxylic acid 27 after five steps. 57 Compound 19 has also been nitrated in position 7 to yield 2-acetyl-7-nitroTHPy.…”

“…74 Instead, better results were obtained when 2-amino-THPy 18 was transformed into the corresponding diazonium salt and treated with NaBF 4 (Scheme 14). 58 This reaction has also been performed on the aromatised analogue 2-aminopyrene 16 under Balz-Schiemann conditions using t-BuONO and Et 2 O•BF 3 . 51 A number of deuterated pyrenes were made via treatment of THPy 12 with P 2 O 5 in D 2 O to give 66.…”