Isomericcis-cyclohexano-13-crown-4 ethers: a low-temperature1H and13C NMR investigation
摘要:
The two positionally isomeric cydohexanotetraoxacyclotridecanes (13-crown-4 ethers) were synthesized and studied via low-temperature NMR methods. For the 1,4,8,11-tetraoxa isomer, the cyclohexane ring inversion is a degenerate process, whereas for the 1,4,7,11-tetraoxa isomer, a preference of 1.4 kJ mol(-1) for the form in which the propyleneoxy group is equatorial was determined. Molecular mechanics calculations using MM+ indicated a preference of 0.6 kJ mol(-1) for this conformer. Resonance assignment was facilitated by the synthesis of a selectively deuterated derivative and by COSY, HMQC and HMBC experiments. The results were compared with those for the related 10-crown-3 system and C-13 chemical shift trends are discussed in terms of MM+ calculated geometries. (C) John Wiley & Sons Ltd.
Preparation de derives de composes crown-4 a cycles de 13 a 16 membres, en vue d'obtenir des ionophores selectifs du lithium. Les mesures potentiometriques montrent que c'est les composes 14-crown-4 et 15-crown-4 qui possedent les meilleurs proprietes
准备 de 派生 de composes Crown-4 a cycle de 13 a 16 membres, en vue d'obtenir des ionophores selectifs du 锂。Les mesures potentiometriques montrent que c'est les composes 14-crown-4 et 15-crown-4 qui possedent les meilleurs proprietes
Czech, Bronislaw P.; Zazulak, Wolodymyr; Kumar, Anand, Journal of Heterocyclic Chemistry, 1991, vol. 28, # 5, p. 1387 - 1394
作者:Czech, Bronislaw P.、Zazulak, Wolodymyr、Kumar, Anand、Dalley, N. Kent、Weiming, Jiang、Bartsch, Richard A.
DOI:——
日期:——
KITAZAWA, SADAYA;KIMURA, KEIICHI;YANO, HIDEKI;SHONO, TOSHIYUKI, J. AMER. CHEM. SOC., 1984, 106, N 23, 6978-6983
WANG, YIKANG;JIN, DAOSEN;YAO, ZHONGQI, ORG. CHEM.,(1987) N 3, 213-215
作者:WANG, YIKANG、JIN, DAOSEN、YAO, ZHONGQI
DOI:——
日期:——
Complexation and solvent extraction of lithium salts with 2,3,6,7,9,10-hexahydro-5H-1,4,8,11-benzotetraoxacyclotridecin (benzo-13-crown-4)
作者:Uriel Olsher、Joseph Jagur-Grodzinski
DOI:10.1039/dt9810000501
日期:——
towards lithium salts of several 12- to 16-membered ring ‘crown’ ethers. The 13-membered ring benzo-13-crown-4 (L1) was found to be the most effective complexing agent for lithium among the investigated macrocyclicethers. The effect of counter ions on the solubility was found to be OH– < Cl– < ClO4–≈ SCN– < picrate. The benzene and the methylene chloride solutions of L1 extract lithium salts selectively