Low temperature 13C NMR study of 1-(3-pentyloxyphenylcarbamoyloxy)-2-dialkyl- aminocyclohexanes |
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Authors: | V. Mlyn rik,L. Bene |
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Affiliation: | V. Mlynárik,L. Beneš |
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Abstract: | Cyclohexane and piperidine ring reversal in 1-(3-pentyloxyphenylcarbamoyloxy)-2-dialkylaminocyclohexanes was investigated by 13C NMR. An unusually low conformational energy ΔG = 0.59 kJ mol?1 and activation parameters ΔG≠218 = 43.8 ± 0.4 kJ mol?1, ΔH≠ = 48.9 ± 2.5 kJ mol?1 and ΔS≠ = 23 ± 9 J mol?1 K?1 were found for the diequatorial to diaxial transition of the cyclohexane ring in the trans-pyrrolidinyl derivative. In the trans-piperidinyl derivative, ΔG222 = 44.7 ± 0.5 KJ mol?1, ΔH≠ = 55.7 ± 6.3 kJ mol?1 and ΔS≠ = 51 ± 21 J mol?1 K?1 was found for the piperidine ring reversal from the non-equivalence of the α-carbons. |
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