Amino Acid-Containing Polyacetylenes: Synthesis, Hydrogen Bonding, Chirality Transcription, and Chain Helicity of Amphiphilic Poly(phenylacetylene)s Carrying <scp>l</scp>-Leucine Pendants
作者:Kevin K. L. Cheuk、Jacky W. Y. Lam、Junwu Chen、Lo Ming Lai、Ben Zhong Tang
DOI:10.1021/ma0344543
日期:2003.8.1
leucine pendants. The polymers are thermally stable (up to ∼260 °C) and undergo Z−E isomerization at ∼200 °C. The chirality transcription from the l-leucine pendants induces the chain segments of polymers 1 to helically spiral predominantly in one preferred direction, while the helicity induction processes in 2 are interrupted by the relaxations of the long flexible spacers between the chiral pendants
[EN] RADICAL TRAP IN FLUORIDATION OF IODONIUM SALT<br/>[FR] CAPTEUR DE RADICAUX DANS LE CADRE DE LA FLUORURATION DE SEL D'IODINIUM
申请人:GE HEALTHCARE LTD
公开号:WO2005061415A1
公开(公告)日:2005-07-07
Decomposition of iodonium salts by a free radical process has been identified as a significant factor in the observed yield variability of fluoridation reactions using said iodonium salts. Accordingly, the inclusion of a free radical trap in the reaction mixture blocks the radical chain decomposition pathway for iodonium salts such that only the reaction leading to fluoridation can occur and the yield of aryl fluoride becomes high and reproducible. The reaction may also be carried out on solid phase. In both the solution and the solid phase the preferred method of the present invention is radiofluoridation.
Decomposition of iodonium salts by a free radical process has been identified as a significant factor in the observed yield variability of fluoridation reactions using said iodonium salts. Accordingly, the inclusion of a free radical trap in the reaction mixture blocks the radical chain decomposition pathway for iodonium salts such that only the reaction leading to fluoridation can occur and the yield of aryl fluoride becomes high and reproducible. The reaction may also be carried out on solid phase. In both the solution and the solid phase the preferred method of the present invention is radiofluoridation.