Use of cryptates in anionic polymerization: Polymerization of styrene

Synthesis and Characterization of Block Copolymers of Poly(ethylene oxide) and Poly(methyl methacrylate)

“…Macrocyclic polyethers (crown ethers) have recently been known to bind effectively alkali metal cations and to increase the nucleophilicities of counter anions. 7 -10 More recently, macroheterobicycles (cryptates) have been found to be more effective in binding alkali metal cations than crown ethersY - 15 We have briefly reported the synthesis of a triblock copolymer of PMMA-PEO-PMMA initiated with the disodium salt of PEO in the presence of a crown ether and a new initiator system. 16 • 17 In this paper, we discuss the detailed nature of the polymerization of MMA prepared with disodium salt of PEO.…”

Unexpected Cleavage of Crown Ether in the Reaction of Methyloxirane with K-,K+(15-crown-5)2

“…The signals due to both metal ions were present in the 39 K NMR spectrum ,, After that only the signal of potassium cation was observed in the spectrum. That means that all metal anions present in the solution took part in the reaction.…”

“…20 The addition of the supramolecular complex solution into the solution of methyloxirane caused an instantaneous discoloration due to the disappearance of potassium anions. 9,21,22 After that only the signal of potassium cation was observed in the spectrum. That means that all metal anions present in the solution took part in the reaction.…”

“…Supramolecular complexes of alkali metals containing metal anions and cations have previously been known as the reducing agents of many organic compounds, − as well as the initiators of polymerization of vinyl monomers, − dienes, , lactones , and oxiranes. − In our earlier work 18 on the use of such complexes to initiate polymerization of methyloxirane, we studied the mechanism of propagation and chain-transfer reactions. The rate constants for these reactions were determined.…”

Novel Electron-Transfer Reactions Mediated by Alkali Metals Complexed by Macrocyclic Ligand

“…Such solutions have been used in organic synthesis, as strong reducing agents [18][19][20][21] or as initiators of polymerization. [22][23][24][25] To achieve reproducibility of these reactions, well-defined metal solutions should be used. Recently, the kinetics of metal dissolution has been examined and the process rationalized.…”