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Herein, we introduce a catalytic system consisting of Pd (OAc)2/Xantphos/Al (OTf)3, which exhibits excellent reactivity in catalyzing the hydroesterification of a wide range of substrates, including electron‐deficient unsaturated acids/esters, aliphatic alkenes, functionalized styrenes, and phenylacetylenes. The catalytic system featured high reactivity and selectivity, low catalyst loading, wide substrate scope, and low CO pressure. Importantly, it eliminated the need for corrosive strong Brønsted acid additives, yielding alkyl‐ or aryl‐substituted dicarboxylic acid esters and monocarboxylic acid ester derivatives that hold significant industrial and pharmaceutical value. Mechanistic studies indicate that the reaction proceeds via the palladium hydride pathway. [ABSTRACT FROM AUTHOR]

A new rotationally hindered diphosphoramidite ligand has been applied to the Rh-catalyzed hydroformylation of various olefins. Good activity as well as excellent regioselectivity toward the formation of linear aldehydes were achieved. Remarkable performances were also observed in the hydroformylation of functionalized olefins, including methyl acrylate, allyl acetate, crotonaldehyde ethylene acetal and styrene. [ABSTRACT FROM AUTHOR]

The catalyst-free oxidative cleavage of (Z)-triaryl-substituted alkenes bearing a pyridyl motif in ambient air under the irradiation of blue LEDs at room temperature has been developed. The reaction was facile and scalable, and proceeded with good functional group tolerance, affording pharmaceutically useful 2-acyl pyridines. The electron paramagnetic resonance (EPR) studies together with control experiments showed that the singlet oxygen (1O2) and superoxide anion (O2˙−) are the reactive oxidants. The 1O2 generation mechanism correlated well with the photophysical properties of the substrate (Z)-triaryl-substituted alkenes, the excited state of which was proved to serve as the triplet sensitizer for the generation of 1O2. [ABSTRACT FROM AUTHOR]

This paper describes the homogeneous catalysis and highly efficient recycling of aqueous catalyst for the hydroformylation of higher olefins in the methanol/water mixed solvent for the first time. When sufficient methanol is added into aqueous HRh(CO)(TPPTS)3/TPPTS solution and 1-hexene, the reaction mixture becomes a single phase at reaction temperature (TPPTS: Trisodium triphenylphosphine-3,3′,3″-trisulfonate), which makes the 1-hexene hydroformylation proceed homogeneously. The turnover number (TON) is 11880 during an hour, and TON is up to 10428 during half an hour at a substrate to catalyst ratio of 12000. After the reaction, the methanol with low boiling point can be readily recovered by distilling the product mixture at the reaction temperature. And then, what's left is the aqueous organic two-phase mixture. The aqueous catalyst solution can be separated from the products by a simple decantation. The recovered aqueous catalyst solution as well as methanol can be recycled for seven runs without significant loss of activity and selectivity for aldehydes. Moreover, the average rhodium leaching in products is less than 0.09 wt%. [ABSTRACT FROM AUTHOR]

The application of polyethylene glycol (donated as PEG), as an environmentally benign solvent instead of water, in rhodium catalyzed hydroformylation of long chain alkenes by using water soluble phosphine BISBIS or TPPTS (TPPTS: sodium salt of sulfonated triphenylphosphine, BISBIS: sodium salt of sulfonated 2,2′-bis(diphenylphosphinomethyl)-1,1′-biphenyl) is herein reported. The conversion of long chain alkenes in PEG-200 could reach above 95.0% after a short reaction time (15 min). In addition, an efficient phase separation and recycling of PEG-200 and catalyst were achieved. The leaching of rhodium into product phase detected by ICP-AES was less than 0.06 wt% of the initial amount. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Abstract: The preparation of a new surface-active sulfonated phosphine and its catalytic performance in aqueous biphasic hydroformylation of long chain olefins were reported. The amphiphilic phosphine: sodium salt of sulfonated n-C12H25O C6H4P(C6H4-p-CH3O)2 (DMOPPS) was prepared by sulfonation of the hydrophobic phosphine DMOPP in concentrated H2SO4 under N2 atmosphere at 30°C for about 5h. The rhodium complex, RhCl(CO)(TPPTS)2 [TPPTS=P(C6H4-m-SO3Na)3], was used as the catalyst precursor. The catalytic active species with the DMOPPS as ligand was in situ formed by adding DMOPPS to the RhCl(CO)(TPPTS)2 catalyst precursor. The surface-activity and micelle-forming property of this new amphiphilic phosphine were confirmed by using cryogenic transmission electron microscope (Cryo-TEM). Under the same conditions, the biphasic hydroformylation of 1-decene using DMOPPS as ligand was compared with that using traditional TPPTS as ligand. The catalysis system using DMOPPS was also compared with the previous Rh-TPPTS-surfactant [C12H25N(CH3)3I (DTAI)] system. Some reaction parameters such as stirring rates, alkyl chain length of olefins, the molar ratio of phosphine/rhodium, and the catalyst recycle were also studied in detail. The results showed that the ligand DMOPPS exhibited a micelle-forming property that could significantly enhance the hydroformylation reaction rate of long chain olefin. Moreover, the surface-active phosphine may also stabilize the aqueous/oil phase boundary, which could enhance the biphasic catalytic reaction rates. [Copyright &y& Elsevier]

Abstract: Six cationic gemini and trimeric surfactants: N,N′-didodecyl-N,N′-dimethyl piperazinium iodide (2), the monooxlate of N,N′-didodecylpiperazine (3), the hydrochloride of N,N′-didodecylpiperazine (4), the 1,3,5-trimethyl-1,3,5-tridodecylhexahydro-1,3,5-trazinium iodide (5), the monooxlate of 1,3,5-tridodecylhexahydro-1,3,5-triazine (6) and the hydrochloride of 1,3,5-tridodecylhexahydro-1,3,5-triazine (7) were prepared using the regular methods. These cationic surfactants and a double-chained surfactant, didodecyldimethylammonium bromide (1), were successfully applied as catalysis promotion agents in aqueous biphasic hydroformylation of higher olefins. The aqueous catalysts used in present study were RhCl(CO)(TPPTS)2–TPPTS [TPPTS: P(m-C6H4SO3Na)3]. The experimental results showed that while all these cationic surfactants could accelerate the hydroformylation reaction, surfactants 1, 2, 6, 7 exhibited more significant promotion effects. The influences of the surfactant anions on the reaction were also discussed. Of the three gemini surfactants 2, 3, and 4, which were derived from N,N′-didodecylpiperazine, surfactant 2 with iodide as anion exhibited substantially higher promotion effect than surfactants 3 with monooxalate and 4 with chloride as anion, respectively. On the other hand, among the three trimeric surfactants 5, 6, 7, which were derived from 1,3,5-tridodecylhexahydro-1,3,5-triazine, surfactants 6 with monooxalate and 7 with hydrochloride as anion displayed better acceleration effect than surfactant 5 with iodide as anion. Compared with the double-chained and single headed surfactant 1, surfactant 2 containing two alkyl chains and cationic heads and surfactant 6 with three alkyl chains and cationic heads were superior additives to accelerate the hydroformylation reactions. When they were used as catalysis promotion additives, less water-soluble phosphine (TPPTS) was required to immobilize the rhodium catalyst in aqueous phase, and the hydroformylation reaction proceeded more regioselectively toward the valuable linear aldehyde under lower syngas pressure. [Copyright &y& Elsevier]

Tetraphosphine and bisphosphine ligands were synthesized, characterized and employed in Rh‐catalyzed hydroformylation of 1‐octene and 1‐hexene. Conversion of over 97.7% and aldehyde yield of 94.1% were achieved at 60°C, 20 bar. This remarkable performance could also be retained at lower temperature (i.e. 40°C) by prolonging the reaction time. The tetraphosphine ligand‐modified Rh catalyst could be reused for at least seven successive runs with catalytic activity and selectivity almost unchanged; the catalyst was separated from the products and recycled directly in homogeneous hydroformylation, indicating that the catalyst might have good stability. 31P NMR and high‐resolution mass spectral characterization hinted that the reason for the reusability of the catalyst might be that the tetraphosphine ligand is relatively air‐stable and is probably slowly oxidized during the recycling runs. The tetraphosphine ligand has four phosphorus atoms to be partially oxidized and could still coordinate with the Rh center via the unoxidized phosphorus atoms to stabilize the catalyst, based on the multiple chelating modes of the tetraphosphine ligand. Hence, the catalytic activity and selectivity could be retained for a certain number of runs. A new air‐stable tetraphosphine ligand‐based catalyst could lead to high conversion (>97.7%) and high aldehyde selectivity (>94.1%) at low temperature (40–60°C). Moreover, the tetraphosphine ligand could chelate with Rh due to the multiple chelating modes even though one or two phosphorus atoms were oxidized, providing at least seven reuses of the catalyst in homogeneous hydroformylation. [ABSTRACT FROM AUTHOR]

Abstract: The biphasic hydroformylation of higher olefins was performed efficiently in the halogen-free ionic liquids 1-n-alkyl-3-methylimidazolium p-toluenesulfonate ([Rmim][p-CH3C6H4SO3]) using Rh-TPPTS [TPPTS: trisodium salt of tri(m-sulphonylphenyl)phosphine] complexes as catalyst. The catalytic system offers high activity and chemoselectivity for aldehyde with a good retention of the catalyst in ionic liquid phase. The ionic liquid containing catalyst can be easily separated and reused several times without a significant decrease in the activity and selectivity. The results indicated that the cation and anion of ionic liquids strongly influenced the reaction rate. Furthermore, the reaction rate was markedly accelerated when the chain-length of alkyl in ionic liquids was comparable with that of olefin. A “matching effect” between the chain-length of alkyl in ionic liquids and that of olefins was firstly reported. [Copyright &y& Elsevier]

[Display omitted] • Non-aqueous biphasic hydroformylation for higher olefins based on formamide was evaluated. • This system shows good activity and aldehyde chemoselectivity under mild condition. • Rhodium could be recycled for at least 40 times, with an average loss of 0.02 wt% for each run. • This system was successfully applied to crude Fischer-Tropsch synthesis higher α-olefins. A simple and recyclable biphasic rhodium catalytic system for the hydroformylation of long-chain alkenes is performed with the presence of Rh/TPPTS (trisodium tris(m-sulfophenyl)phosphine) in highly polar formamide for the first time. This work investigated the phase behavior of 1-octene, 1-nonanal and formamide, as well as the factors affecting the catalytic performance and catalyst recovery. Two phases were fully separated with distinct interface, allowing facile recycle of catalyst-containing formamide solution by decantation. Hydroformylation could be carried out under mild condition with turnover frequency and aldehyde selectivity up to 950 h−1 and 97 %, respectively. The catalyst could be reused for at least 40 runs without obvious activity and selectivity decline. No extra rhodium or TPPTS was needed during the cycle runs, and the average rhodium loss for each cycle was as low as 0.02 wt%. This system has also been successfully applied to the hydroformylation of crude higher α-olefins with high conversion and rhodium reservation, which were just distilled from Fischer-Tropsch synthesis with 64.7∼81.0 % fraction. [ABSTRACT FROM AUTHOR]