Fast colorimetric evaluation of optimum conditions for the synthesis of fluorescent molecular probes: Application to neuronal tracers N,N-((dialkyiamino)styryl)-N-alkylpyridinium salts

cited By 4International audienceThe present communication reports the detection of new phosphorus- containing semilabile ligands for the Heck coupling reaction. We have developed a new screening methodology based on the batochrome properties of the cross-conjugated target molecules to rapidly test a large diversity of metal/ligand complexes for this coupling reaction. © 2005 Wiley-VCH Verlag tGmbH & Co. KGaA

High temperature initiator-free RAFT polymerization of methyl methacrylate in a microwave reactor

The reversible addition–fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) was investigated under microwave irradiation. At first, a comparison was made between microwave and thermal heating for the RAFT polymerization of MMA with azobis(isobutyronitrile) (AIBN) as initiator and 2-cyano-2-butyldithiobenzoate (CBDB) as RAFT agent, revealing comparable polymerization kinetics indicating the absence of non-thermal microwave effects. Second, the CBDB-mediated RAFT polymerization of MMA was investigated at high temperatures (120 ◦ C, 150 ◦ C, and 180 ◦ C, respectively) in the absence of a radical initiator, showing a linear increase of the molar masses with conversion. The polydispersity indices remained below 1.5 up to 25% MMA conversion at 120 ◦ C and 150 ◦ C, indicating a controlled polymerization. This control over the polymerization was confirmed by the ability to control the molar masses by the concentration of RAFT agen

Optimization of Ring-Closing Metathesis: Inert Gas Sparging and Microwave Irradiation

A systematic study of a ring-closing metathesis towards a tetrasubstituted double bond as part of a seven-membered ring in a 5.7.5-tricyclic guaianolide system is described. By combining two techniques, namely sparging an inert gas through the solution together with dielectric heating via microwave irradiation a high-yielding ring-closing metathesis reaction in this particularly challenging case was achieved. The results obtained compare favorably with conventional heating conditions or with microwave irradiation in a closed system. The key aspects seem to be that rapid microwave irradiation diminishes catalyst decay by allowing the required high reaction temperature to be reached quickly and homogeneously and thereby providing enough energy for a successful metathesis reaction, while inert gas sparging is purging off evolving ethylene to shift the equilibrium to the product