LONG RANGE NUCLEAR SPIN-SPIN COUPLING. ALLENIC AND POLYACETYLENIC SYSTEMS
CALIFORNIA INST OF TECH PASADENA GATES AND CRELLIN LABS OF CHEMISTRY
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A study was made to determine the magnitude and sign of coupling constants in allenic derivatives and to investigate some saturated systems for which significant super long-range coupling constants might reasonably be expected. Spinspin coupling between protons separated by 5 to 9 chemical bonds were observed in allenic and polyacetylenic systems. Analysis of the nuclear magnetic resonance spectrum of 1-chloro-1,2butadiene permitted the assignment of a negative sign to J13 opposite to the positive signs of J12 and J14. The relation of these results to the theory of proton-proton spin-spin coupling is discussed.