6533b7cefe1ef96bd1256e84
RESEARCH PRODUCT
THE KINETICS AND MECHANISM OF THE REACTION OF ONIUM CYCLOPENTADIENYLIDES WITH TETRAHALO-p-BENZOQUINONES
Donald B. DenneyFrancisco Pérez PlaRosa ValeroC. Dennis HallPeter Speerssubject
Nucleophilic additionArylOrganic ChemistryOniumPhotochemistryBiochemistryMedicinal chemistryHomonuclear moleculeQuinoneInorganic Chemistrychemistry.chemical_compoundHeteronuclear moleculechemistryNucleophileNucleophilic aromatic substitutiondescription
Abstract The reaction of triphenylphosphonium cyclopentadienylide (1) with halogen-substituted p-benzoquinones (4) is shown to give a new class of dipolar (zwitterionic) dyes (5) containing phosphorus. The general structure of these molecules has been investigated by a combination of mass spectrometry and multinuclear (7H, 13C and 31P) nmr using the specialist techniques of DEFT spectroscopy, homonuclear (COSY) and heteronuclear 2-D nmr. In addition, stopped-flow (uv/visible) techniques have been used to study the kinetics of the reactions and hence demonstrate that the rate-limiting step is nucleophilic addition of the ylid nucleophile to the quinone, followed by a rapid loss of halide ion. This mechanism follows the classical pattern associated with nucleophilic aromatic substitution in activated aryl halides.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1989-10-01 | Phosphorus, Sulfur, and Silicon and the Related Elements |