147514-81-6Relevant articles and documents
Fluorous catalysis under homogeneous conditions without fluorous solvents: A "greener" catalyst recycling protocol based upon temperature-dependent solubilities and liquid/solid phase separation
Wende, Marc,Gladysz
, p. 5861 - 5872 (2003)
The thermomorphic fluorous phosphines P((CH2)m(CF2)7CF3)3 (m = 2, 1a; m = 3, 1b) exhibit ca. 600-fold solubility increases in n-octane between -20 (1a = 0.104 mM) and 80 °C (63.4 mM) and 1500-fold solubility increases between -20 and 100 °C (151 mM). They catalyze conjugate additions of alcohols to methyl propiolate under homogeneous conditions in n-octane at 65 °C and can be recovered by simple cooling and precipitation and used again. This avoids the use of fluorous solvents during the reaction or workup, which are expensive and can leach in small amounts. Teflon shavings can be used to mechanically facilitate recycling, and 31P NMR analyses indicate >97% phosphorus recovery (85.2% la, 12.2% other). 19F NMR analyses show that 2.3% of the (CF2)7CF3 moieties of 1a reach, in some form, into the n-octane (value normalized to phosphorus). 1a similarly catalyzes additions in the absence of solvent. Yield data match or exceed those of reactions conducted under fluorous/organic liquid/liquid biphase conditions. The extra methylene groups render 1b more nucleophilic than la and, thus, a more active catalyst. The temperature dependence of the solubility of la is measured in additional solvents and compared to that of the nonfluorous phosphine PPh3.
Fluorous catalysis without fluorous solvents: A friendlier catalyst recovery/recycling protocol based upon thermomorphic properties and liquid/solid phase separation [5]
Wende,Meier,Gladysz
, p. 11490 - 11491 (2007/10/03)
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