31250-18-7Relevant articles and documents
Alkaline Earth Cryptates: Dynamics and Stabilities in Different Solvents
Cox, B. G.,Truong, Ng van,Schneider, H.
, p. 1273 - 1280 (1984)
The stability constants and rates of formation and dissociation of alkaline earth cryptates with (2,1,1), (2,2,1), (2,2,2), (2B,2,2), and (2B,2B,2) have been measured in several solvents.The stability constants, Ks, are considerably larger and display higher selectivity than those of the monocyclic crown and diaza crown ethers and anionic ionophores.Values of Ks vary by over 10 orders of magnitude in the different solvents, increasing in the order Me2SO d).The rates show no correlation with solvent exchange rates, and are sensitive to cation size, cation-solvent interactions, and ligand flexibility.In strongly solvating media such as Me2SO, rates are up to 106 lower than predicted by a simple Id mechanism.The results suggest that the complexation reaction involves essentially stepwise replacement of solvent by ligand donor atoms, but that even for relatively flexible macrocyclic ligands compensation for loss in solvation by ligand binding energy in the transition state is not complete.
Synthesis of azacrown ethers and benzocryptands by macrocyclization of podands at high concentrations of reactants
Oshchepkov,Perevalov,Kuzmina,Anisimov,Fedorova
experimental part, p. 478 - 485 (2011/11/05)
The reactions of 1,2-bis(2-Y-ethoxy)benzenes, N,N-bis(2-Y-ethyl)-N- phenylamines, or 2,6-bis(Y-methyl)pyridines (Y = I, Br, or OTs) with α,ω-polyoxaalkanediamines or diazacrown ethers in the presence or absence of alkali carbonates in a concentrated acetonitrile solution of the reactants afforded the corresponding azacrown ethers or cryptands in high yields.
Synthesis of Simple Cryptands under High Pressure
Pietraszkiewicz, Marek,Salanski, Piotr,Jurczak, Janusz
, p. 433 - 436 (2007/10/02)
Simple N,N'-dimethyl diaza-crown ethers react with bis(2-iodoethyl)-ether (2a) and 1,2-bis(2-iodoethoxy)ethane (2b) under high pressure (10 kbar) to give bis-quaternary salts which are demethylated in good yield by triphenylphosphine in boiling dimethylformamide yielding simple cryptands.
