Rhodium catalyzed hydroformylation of 1-octene in microemulsion: comparison with various catalytic systems
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Catalysis Letters Vol. 110, Nos. 3–4, September 2006 (Ó 2006) DOI: 10.1007/s10562-006-0109-8
Rhodium catalyzed hydroformylation of 1-octene in microemulsion: comparison with various catalytic systems Hesna Hu¨lya Yildiz U¨nverena,b,* and Reinhard Schoma¨ckera a
Institut fu¨r Chemie, Technische Universita¨t Berlin, Sekretarait TC 8, Straße des 17. Juli 124-128, 10623 Berlin, Germany b Lehrstuhl fu¨r Physikalische Chemie II, Universita¨t Erlangen-Nu¨rnberg, Egerlandstraße 3, 91058 Erlangen, Germany
Received 21 April 2006; accepted 11 June 2006
In this work, we describe how addition of alkylpolyglycol ether type nonionic surfactant affects the hydroformylation of 1-octene in the presence of phosphine modified rhodium catalyst. Influence of different process parameters such as ligand excess and amount of surfactant on the reaction rate and selectivity were discussed. Direct comparison of microemulsion systems with classic processes was achieved by performing the reactions under comparable homogeneous and biphasic conditions. Thus, the experiments were carried out using catalysts such as unmodified rhodium carbonyl HRh(CO)4 and HRh(CO)(PPh3)3 in homogeneous system, Rh–TPPTS complex in two-phase system and in association with co-solvent. KEY WORDS: hydroformylation; microemulsion; 1-octene; nonionic surfactant; rhodium complex; water-soluble catalyst.
1. Introduction Hydroformylation of olefins is an important, well-known commercial process for the production of aldehydes and alcohols, moreover it is one of the most important applications of homogeneous catalysis in industry as well [1]. The history of aqueous, biphasic homogeneous catalysis starts with the initial observation by Manassen [2]. Since the first industrial use of this system in 1984 by the hydroformylation of propylene in the plants of Ruhrchemie A.G., research into aqueous, two phase, homogeneous catalysis has become very active [3,4]. Two basic problems in classical homogeneous catalysis, namely the separation and subsequent recycling of the catalyst can be elegantly solved by using two-phase catalysis, in which the catalyst and the product enables to be separated by simple phase separation [5]. However, if we compare biphasic reactions with their monophasic equivalents, it is found that the rates are lower in the two-phase systems [6]. Although the use of water as a second phase has many advantageous [4], it has also its limitations, especially when the water solubility of starting materials is too low, preventing adequate transfer of the organic substrate into aqueous phase or at the phase boundary and consequently reducing the reaction rates [7]. Therefore, this process is not economically viable for long chain alkenes, which are not very soluble in water. One useful way to overcome this solubility problem that is frequently encountered in organic reactions is *To whom correspondence should be addressed. E-mail: [email protected]
performing the reaction in a microemulsion [8,9]. A microemulsion is formed by adding a suitable surfa
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