Analysis of Weakly Coupled Nuclear Magnetic Resonance Spectra: Methyl Salicylate

The proton magnetic resonance spectrum of methyl salicylate at 60 Mc/sec is sufficiently weakly perturbed for all the strong lines to be assigned on a ``first-order'' basis. The frequency sweep double irradiation method has been used to demonstrate that all the spin coupling constants in the aromatic ring have the same sign. This makes possible the calculation of accurate values of the chemical shifts and spin coupling constants by iterative computer analysis without the need for examining other sign combinations. There is an unexpected long-range coupling (0.4 cps) between the hydroxyl proton and one of the ring protons in the meta position.