Hydroformylation of olefins catalyzed by transient montomorillonite rhodium (II) catalyst

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "dejavu="" sans";mso-hansi-theme-font:minor-latin;mso-bidi-font-family:mangal;="" mso-bidi-theme-font:minor-bidi;color:#00000a;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Transient [Rh^IIH(CO)(PPh₃)₂]^- <b>2</b> complex obtained by the reaction of synthesis gas with montmorillonite loaded complex [Rh(PPh₃)₃]⁺<b>1</b> catalyzes the hydroformylation of allyl alcohol at 70°C and 60atm CO + H₂ (1:1) in alcoholic solvents to give &gt; 96% yield of the linear product (<i style="mso-bidi-font-style:normal">L</i>) 4-hydroxybutyraldehyde with branched (<i style="mso-bidi-font-style:normal">B</i>)/linear product mole ratio 0.04. The activity of <b>2</b> is greatly influenced by the alcoholic solvents used in the hydroformylation reaction; the longer the carbon chain higher the activity of the catalyst with the loss of selectivity (<i>B/L</i> ratio 0.08-0.14). The activity is compared with the Wilkinson catalyst [Rh¹H(CO)(PPh₃)₂] <b>6</b> in homogeneous conditions. Complex <b>6</b> is found to be five times more reactive than <b>2</b> but with a loss of selectivity in the hydroformylation of allyl alcohol which gives 4-hydroxybutyraldehyde (65%) (<i>B/L</i> ratio 0.54) in ethanol. Similar observations have been found in the hydroformylation reactions of styrene, 4-chlorostyrene, cyciohexene and 1,3-butadiene to give corresponding products.</span>