Novel basic ligands for the homogeneous catalytic carbonylation of methanol: Part XXII . Preparation and characterization of ether-phosphanes attached to silica gel by spacers of three and six carbon atoms

Abstract

The silylalkyl(ether-phosphanes) X n Me 3− n S(CH 2) m+2 P(Ph)D ( 3a, b, e, 4a, b, e, 5a) [X = Cl, OMe; m = 1, 4; n = 1, 3; D = CH 2C 4H 7O 3 (3), CH 2C 4H 7O (4), CH 2CH 2OCH 3 (5)] are obtained by a photochemically induced addition of the secondary phosphanes HP(Ph)D to the olefinic double bond of the ω-alkenylchloro- and (ω-alkenylmethoxysilanes X n Me 3- n Si(CH 2) m CHCH 2. The corresponding silylalkyl(ether-phosphanes) 3c, d, 4c, d and 5c are obtained from the reaction of the chloropropylmethoxymethylsilanes X n Me 3- n Si(CH 2) m+2 Cl ( 2c, d) with HP(Ph)D in the presence of NaH. The ligands 3a, b, d, e, 4 a, b, d, e and 5a can be covalently anchored to silica gel. For HCl removal, lutidine is used as an auxiliary base in the case of the chlorine-containing silylalkyl(ether-phosphanes) 3a, b, 4a, b and 5a. 13C, 29Si and 31PCP-MAS NMR spectra indicate successful heterogenization, thus giving some insight into the nature of the bonding of the ligands with the surface of silica gel. The ligands, when combined with cobalt iodide, give rise to systems which are catalytically active in the carbonylation of methanol, preferably to acetaldehyde with selectivities of 50–60% at conversions not higher than 30%.