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A proton and carbon NMR spectroscopic study of 5‐substituted acenaphthenes
Author(s) -
Vasuki Gnanasambandam,
Perumal Subbu,
Vijayabaskar Veerappan,
Selvaraj Sangavanaickar,
Ramalingam M.,
Venuvanalingam P.
Publication year - 1998
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199812)36:12<943::aid-omr383>3.0.co;2-h
Subject(s) - chemistry , substituent , chemical shift , polarizability , steric effects , acenaphthene , carbon 13 nmr , carbon fibers , resonance (particle physics) , proton , stereochemistry , computational chemistry , organic chemistry , naphthalene , molecule , materials science , physics , composite number , composite material , particle physics , quantum mechanics
The proton and carbon NMR spectra of eight5‐substituted acenaphthenes were obtained. The 13 Cchemical shifts of C‐6 and C‐2a of these compounds werecompared with those of carbons located at structurally similarpositions in 1‐substituted naphthalenes (viz. C‐8and C‐4). The 13 C chemical shifts ofC‐2a were also analysed using the dual substituent parameter(DSP) equation. The results revealed (i)diminished steric interactions between the 5‐substituent andthe adjacent peri ‐carbon (C‐6) and(ii) an enhanced transmission of both polar and resonanceeffects to the carbon para (C‐2a) to thevariable substituent, X, in acenaphthenes relative to thecorresponding carbons (C‐4) in 1‐substitutednaphthalenes. The higher ρ I and ρ R values observed for C‐2a of acenaphthenes suggest higherpolarizability in this system than in naphthalenes. AM1 calculationsof charge also showed enhanced substituent effects in the case of mostof the substituents in the acenaphthene system. © 1998 John Wiley& Sons, Ltd.