Organophosphorus chemistry without PCl3: A bridge from hypophosphorous acid to H-phosphonate diesters
A process for the conversion of hypophosphorous acid (H3PO 2, HPA) and alcohols into various H-phosphonate diesters [(RO) 2P(O)H] is described. The new reaction provides a missing bridge between HPA and important H-phosphonates, completely avoiding the use of PCl3. Nickel chloride or nickel on silica catalyze the oxidative phosphorylation of alkyl phosphinates with various alcohols or water. The reaction is atom economic and avoids the formation of waste products. The previous need for both chlorine and base is completely avoided. Esterification of hypophosphorous acid followed by reaction with another molecule of alcohol under the action of a nickel catalyst provides a green method for the preparation of H-phosphonates. This method entirely avoids the need for any stoichiometric chloride unlike those based on phosphorus trichloride. Copyright
Fisher, Henry C.,Prost, Lucie,Montchamp, Jean-Luc
p. 7973 - 7978
(2014/01/06)
Silver Clusters and Nanoparticles: Preparation in Water-in-Oil Microemulsions and Some Physical Properties
Silver clusters and colloidal nanoparticles were prepared by reducing AgNO3 with sodium hypophosphite in water-in-oil microemulsions in the presence of a mixture of ethoxylated alkylphenols as a surface-active substance (SAS). Ag/SAS/Al2O3 materials containing 0.04-0.13 wt % Ag were prepared by applying the microemulsions to an Al2O3 support and studied by diffuse reflection electronic spectroscopy, small-angle x-ray scattering, and x-ray diffraction. Ag particles in Ag/SAS/Al203 materials have a mean size of ?70 A. The absorption band at 385 nm in the electronic spectra indicates that the nanoparticles consist of isolated clusters.
Pavlyukhina,Zaikova,Odegova,Savintseva,Boldyrev
p. 109 - 113
(2008/10/08)
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