Leendert Maat

Bio: Leendert Maat is an academic researcher from Delft University of Technology. The author has contributed to research in topics: Opium alkaloids & Thebaine. The author has an hindex of 20, co-authored 155 publications receiving 1244 citations.

Catalytic conversions in water. Part 6. A novel biphasic hydrocarboxylation of olefins catalyzed by palladium TPPTS complexes (TPPTS=P(C6H4-m-SO3Na) 3)

Abstract: Exceptionally high catalytic activities (TOF>2500 h-1) have been achieved in the biphasic hydrocarboxylation of propene catalysed by water-soluble Pd/TPPTS complexes. The activity was even higher than that exhibited by organic-soluble Pd/PPh3 systems. This contrasts with the general perception that biphasic catalysis normally exhibits lower rates compared to analogous reactions in organic media. The hydrocarboxylation of 4-isobutylstyrene to ibuprofen and of styrene in a two-phase system is also reported.

Ether Formation in the Hydrogenolysis of Hydroxymethylfurfural over Palladium Catalysts in Alcoholic Solution

Abstract: 5-Hydroxymethylfurfural, a product from renewable feedstock, was subjected to hydrogenolysis over palladium catalysts in 1-propanol aiming at the synthesis of 2,5-dimethylfuran, a potential transportation fuel enhancer. Intermediates are 5-hydroxymethyl-2-(propyloxymethyl)furan, formed with high selectivity, and 5-methyl-2-(propyloxymethyl)furan. Acetals are assumed to be initially formed. Acetalisation and hydrogenolysis are catalysed by traces of a Bronsted acid. Important variables are the palladium support and the solvent. In 2-propanol also ether formation takes place. In 1,4-dioxane mainly 2,5-bis(hydroxymethyl)furan is formed, in water ring opening becomes a major reaction. The formation of some side-products is discussed.

Catalytic conversions in water. Part 5: Carbonylation of 1‐(4‐isobutylphenyl)ethanol to ibuprofen catalysed by water‐soluble palladium–phosphine complexes in a two‐phase system

Abstract: 1-(4-Isobutylphenyl)ethanol (IBPE) was carbonylated to 2-(4-isobutylphenyl)propionic acid (ibuprofen) in an aqueous/organic two phase system using the water-soluble Pd(tppts) 3 catalyst [tppts = P(C 6 H 4 -m-SO 3 Na) 3 ] in the presence of p-CH 3 C 6 H 4 SO 3 H at 363 K, 15 MPa CO pressure and a palladium concentration of 150 ppm without addition of organic solvents. Under these conditions the conversion of IBPE was 83% and the selectivity to ibuprofen 82% with no decomposition of the Pd(tppts) 3 catalyst. Both the activity and selectivity were strongly influenced by the tppts/Pd molar ratio and the nature of the added Bronsted acid. Maximum efficiency was observed for P/Pd = 10. Acids of weakly or non-coordinating anions, such as p-CH 3 C 6 H 4 SO 3 H, CF 3 COOH or HPF 6 afforded carbonylation. No catalytic activity was observed in the presence of acids of strongly coordinating anions, such as HI. The water-soluble Pd/dppps catalyst [dppps = Ar 2-n Ph n P-(CH 2 ) 3 -PP h Ar 2-h ; Ar = C 6 H 4 -m-SO 3 Na; n = n = 0: 86% and n = 0, n = 1: 14%] exhibited low catalytic activity and the major product obtained was the linear isomer of ibuprofen, 3-(4-isobutylphenyl) propionic acid (3-IPPA) with selectivities up to 78%. Replacement of tppts by a ligand containing less -SO 3 Na groups such as monosulphonated triphenylphosphine (tppms) gives rise to a dramatic drop in the catalytic activity and selectivity to ibuprofen. No catalytic activity was observed using palladium catalysts modified with 2-pyridyldiphenylphosphine (PyPPh 2 )and tris(2-pyridyl) phosphine (PPy 3 ) which are both water soluble in their protonated form. A catalytic cycle is proposed to explain the observed results.

Heteropoly acid-catalyzed Diels-Alder reactions

Abstract: Tungstophosphoric acid supported on silica gel has been shown to catalyze Diels-Alder reactions of quinones. The catalyst is active under mild conditions and can be easily recovered and re- used.

Hydroxymethylfurfural, A Versatile Platform Chemical Made from Renewable Resources

Abstract: Renewable Resources Robert-Jan van Putten,†,‡ Jan C. van der Waal,† Ed de Jong,*,† Carolus B. Rasrendra,‡,⊥ Hero J. Heeres,*,‡ and Johannes G. de Vries* †Avantium Chemicals, Zekeringstraat 29, 1014 BV Amsterdam, the Netherlands ‡Department of Chemical Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands DSM Innovative Synthesis BV, P.O. Box 18, 6160 MD Geleen, the Netherlands Department of Chemical Engineering, Institut Teknologi Bandung, Ganesha 10, Bandung 40132, Indonesia

Organic Reactions in Aqueous Media with a Focus on Carbon−Carbon Bond Formations: A Decade Update

Abstract: 4.2.8. Reductive Coupling 3109 5. Reaction of Aromatic Compounds 3110 5.1. Electrophilic Substitutions 3110 5.2. Radical Substitution 3111 5.3. Oxidative Coupling 3111 5.4. Photochemical Reactions 3111 6. Reaction of Carbonyl Compounds 3111 6.1. Nucleophilic Additions 3111 6.1.1. Allylation 3111 6.1.2. Propargylation 3120 6.1.3. Benzylation 3121 6.1.4. Arylation/Vinylation 3121 6.1.5. Alkynylation 3121 6.1.6. Alkylation 3121 6.1.7. Reformatsky-Type Reaction 3122 6.1.8. Direct Aldol Reaction 3122 6.1.9. Mukaiyama Aldol Reaction 3124 6.1.10. Hydrogen Cyanide Addition 3125 6.2. Pinacol Coupling 3126 6.3. Wittig Reactions 3126 7. Reaction of R,â-Unsaturated Carbonyl Compounds 3127

Biocatalysis in ionic liquids

Abstract: Roger Sheldon (1942) received a PhD in organic chemistry from the University of Leicester (UK) in 1967. This was followed by post-doctoral studies with Prof. Jay Kochi in the U.S. From 1969 to 1980 he was with Shell Research in Amsterdam and from 1980 to 1990 he was R&D Director of DSM Andeno. In 1991 he moved to his present position as Professor of organic chemistry and catalysis at the Delft University of Technology (The Netherlands). His primary research interests are in the application of catalytic methodologies—homogeneous, heterogeneous and enzymatic—in organic synthesis, particularly in relation to fine chemicals production. He developed the concepts of E factors and atom utilization for assessing the environmental impact of chemical processes.