Iterative analysis of the 1H NMR spectra of naphthalene (AA′ A″ A‴ BB′ B″ B‴ system) and two of its derivatives

✍ Scribed by Luigi Cassidei; Oronzo Sciacovelli

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 580 KB
• Volume: 15
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270150309

✦ Synopsis

Abstract

The ^1^H NMR spectra of naphthalene as an eight spin system, and two of its derivatives, 2,4‐dichloro‐ and 2,4‐dinitro‐1‐naphthol, have been completely analysed. The Indor technique has been very useful in the determination of the signs and magnitudes of very small coupling constants. An improved version of the Laocoon 3 program has greatly facilitated the spectral analysis through, first, the knowledge of the dependence of each transition upon the spectral parameters; second, some modifications in the iterative loop which avoid failure of convergence, and, third, the use of a slightly modified diagonalization subroutine which saves 20% CPU computer time. Our data suggest a rather small substituent effect on intra‐ring couplings of the unsubstituted ring. The inter‐ring coupling constants display a negative or positive sign according to an even or odd number of intervening bound, except the all‐trans ^6^J which is positive. No substituent effect on the inter‐ring couplings has been observed, except a small effect for the all‐trans ^6^J.