STRUCTURES OF POLYCHLORINATED NAPHTHALENES AND OXYNAPHTHALENES AND THEIR C-13 NMR CHEMICAL-SHIFTS

The increment scheme for calculating chemical shifts of polysubstitute d naphthalenes is based on 1- and 2-substituted heterosubgraphs which describe the main part of the substituent effect. The influence of sev eral substituents on C-13 NMR chemical shifts have been described by t wo-particle increments corresponding to 1,2- and 2,3-ortho-disubstitut ed heterosubgraphs (the steric interaction of substituents in the same ring) and also to 1,4-conjugation of the substituents. Conjugation of two benzene rings required the introduction of a two-particle 1,8-het erosubgraph to the increment system. The systems of two-particle incre ments were obtained for polychlorinated naphthalenes, oxynaphthalenes, and polychlorinated oxynaphthalenes. Predicted C-13 NMR spectra of po lychlorinated naphthalenes not included in the increment analysis prov ed to be in good agreement with independent measurements.