Development of stopped-flow instrument with spectrophotometric detection for the study of fast reactions in supercritical carbon dioxide; kinetics ofmetalloporphyrin formation in supercritical carbon dioxide

A high-pressure stopped-flow instrument with spectrophotometric detection h as been developed, which enables us to follow fast reactions with half-live s longer than 10 ms in supercritical carbon dioxide (scCO(2)) at various te mperatures up to 150 degreesC and pressures up to 30 MPa. The rate of the m etalloporphyrin formation reaction in scCO(2) between 5,10,15,20-tetrakis(p entafluorophenyl)porphyrin and bis(1,1,1,5,5,5-hexaflucoro-2,4-pentanediona to)copper(II) (Cu(hfac)(2)) was successfully measured under a variety of ex cess concentrations (Ccu) of Cu(hfac)(2)Based on the dependence of the cond itional first-order rate constants on C-Cu, the metalation mechanism was ev aluated in scCO(2). (C) 2001 Elsevier Science B.V. All rights reserved.