Aqueous biphasic olefin hydroformylation catalyzed by water-soluble rhodium complexes

Catalysis with water-soluble rhodium complexes, RhCl(CO)(TPPMS)₂, [TPPMS = P(C₆H₅)₂(C₆H₄SO₃)] (1), RhCl(CO)(TPPDS)₂, [TPPDS = P(C₆H₅)(C₆H₄SO₃)₂] (2) and RhCl(CO)(TPPTS)₂, [TPPTS = P(C₆H₄SO₃)₃] (3) in hydroformylation of 1-hexene, 2-pentene, 2,3-dimethyl-1-butene, cyclohexene and several mixtures of these olefins have been studied, under moderate reaction conditions (T: 50–150 °C; pCO/pH₂ = 1; total p: 14–68 bar; Substrate/Catalyst: 600/1) in biphasic toluene/water media. The catalytic system shows high activity but low selectivity. The linear and branched oxygenated products obtained are equally useful in naphtha upgrading, as observed in the real El Palito naphtha tried. The catalysts can be recycled several times without significant activity loss.     

Mono-Sulfonated Derivatives of Triphenylphosphine, [NH4]TPPMS and M(TPPMS)2 (TPPMS = P(Ph)2(m-C6H4SO− 3); M = Mn2+, Fe2+, Co2+ and Ni2+). Crystal Structure Determinations for [NH4][TPPMS]·½H2O, [Fe(H2O)5(TPPMS)]TPPMS, [Co(H2O)5TPPMS]TPPMS and [Ni(H2O)6](TPPMS)4·H2O

Preparation of the ammonium salt of TPPMS, [NH₄]TPPMS, TPPMS = PPh₂(m-C₆H₄SO^? ₃), greatly enhances water solubility and provides an efficient route to other metal complexes of TPPMS, M(TPPMS)₂ M = Mn²⁺, Co²⁺, Fe²⁺ and Ni²⁺. For Co²⁺ and Fe²⁺ the metal has an octahedral ligand environment with five water molecules and one TPPMS coordinated through the sulfonate oxygen; the second TPPMS is not coordinated. For Ni²⁺ the octahedral coordination sphere is composed of water molecules and the TPPMS ligands are not coordinated. Structures are fully reported for [NH₄]TPPMS·½H₂O and [Fe(H₂O)₅(TPPMS)]TPPMS and partially reported for [Co(H₂O)₅TPPMS]TPPMS and [Ni(H₂O)₆]TPPMS₂·H₂O. All of the structures show hydrophobic regions consisting of aromatic rings and hydrophilic regions with hydrogen-bonding interactions.     

1‐Dodecene Hydroformylation Catalyzed by Water Soluble Rhodium Phosphine Complex in Two‐Phase System

1‐Dodecene hydroformylation catalyzed by water soluble rhodium complex [RhCl(CO) (TPPTS)₂] was studied in the presence of TTPTS [P(m‐C₂H₄SO₃Na)₃] and CTAB (cetyltrimethyl ammonium). The influence of reaction parameters was discussed in detail based on micelle effect in biphasic system. The modification for the microcircumstance of micelle interface was conducted by the introduction of a catalyst promoter TPPDS [PhP(m‐C₂H₄SO₃Na)₂] into the reaction solution. A synergistic effect between TPPDS and TPPTS on the regioselectivity of 1‐dodecene hydroformylation was observed. The selectivity of linear aldehyde in the products was so high as 95.7% at the molar ratio of [TPPDS]/[TPPTS] = 0.5.     

Asymmetric hydrogenation of aromatic ketones catalyzed by achiral monophosphine TPPTS-stabilized Ru in ionic liquids

Achiral monophosphine TPPTS [TPPTS: P(m-C₆H₄SO₃Na)₃]-stabilized Ru was synthesized by reduction of RuCl₃·3H₂O with hydrogen in ethanol using TPPTS as the stabilizer. The catalytic asymmetric hydrogenation of aromatic ketones using TPPTS-stabilized Ru modified by a chiral diamine (1R,2R)-DPENDS [disodium salt of sulfonated (1R,2R)-1,2-diphenyl-1,2-ethylene-diamine] was investigated in hydrophilic ionic liquid [RMIM]Ts (1-alkyl-3-methylimidazolium p-methylphenylsulfonates, R = ethyl, butyl, octyl, dodecyl, hexadecyl). Hundred percent conversion and 85.1% ee were obtained for acetophenone under optimized conditions. The resulting products can be easily separated from the catalyst immobilized in ionic liquid by simple extraction with n-hexane, and the catalyst can be reused several times without a significant loss of ee value or conversion. In particular, the addition of water can improve the catalyst performance.     

Synthesis of bis(2-haloalkyl) selanes and selenides based on selenium dioxide and terminal alkenes

Selenium tetrahalides generated from selenium dioxide and hydrogen halides (HCl, HBr) reacted with hex-1-ene, hept-1-ene, and oct-1-ene at a SeO₂?alkene molar ratio of 1: 2 to give mixtures of dihalobis-(2-haloalkyl)-λ⁴-selanes (yield 80?90%) and bis(2-haloalkyl) selenides (yield 5?12%). Halogenation of the resulting mixtures afforded 85?93% (calculated on the initial SeO₂) of the corresponding dihalobis(2-haloalkyl)-λ⁴-selanes, and the reduction of the same mixtures with Na₂S₂O₅ gave bis(2-haloalkyl) selenides in 80?86% yield. In the reaction with a SeO₂?alkene ratio of 5: 8, pure dihalobis(2-haloalkyl)-λ⁴-selanes were formed in 84?93% yield. Dichlorobis(2-chloro-2-phenylethyl)-λ⁴-selane was obtained in 72% yield in the reaction of SeO₂?HCl with styrene.     

Structural studies on platinum alkene complexes and precursors

A number of platinum complexes, precursors to alkene complexes (Pt₂Cl₄(PPh₃)₂ and cis-PtCl₂(CH₃CN)(PPh₃)), alkene complexes (cis-PtCl₂(C₂H₄)(PPh₃), cis-PtCl₂(C₃H₆)(PPh₃) and cis-PtCl₂(1-C₆H₁₂)(PPh₃)), the diamination product of a 1,3-butadiene platinum complex and the 1,2,3,4-tetramethylcyclobutadiene complex resulting from dimerization of 2-butyne have been synthesized, characterized and the structures determined by X-ray diffraction. The ethylene complex, cis-PtCl₂(C₂H₄)(PPh₃), has been a useful reagent for preparing other alkene complexes. Reaction of a bound butadiene complex with diethylamine yielded a diamination product with anti-Markovnikov stereochemistry. An attempt at binding cis-butyne to the metal center resulted in metal-assisted formation of 1,2,3,4-tetramethylcyclobutadiene with previously unreported geometry.     

ortho-, meta- and para-nitrophenylgold(I) complexes

Treatment of [BzPh₃P][AuCl₂] with [Hg(x-C₆H₄NO₂)₂] (x = o, m, or p) gives anionic gold(I) complexes of the type [BzPh₃P][Au(R)Cl](R = o-, m- or p-C₆H₄NO₂, Bz = C₆H₅CH₂). The chloro ligand in [Au(o-C₆H₄NO₂)Cl]^? can be replaced by bromo or iodo ligands by use of NaBr or NaI. The anions [Au(R)Cl]^? react with neutral monodentate ligands, L, to give neutral mononuclear complexes [Au(R)L] (R = o-C₆H₄NO₂, L = PPh₃, AsPh₃; R = m-C₆H₄NO₂, L = PPh₃) and with 1,2-bis(diphenylphosphino)ethane (dpe) to give [Au₂(R)₂(dpe)] (R = o-C₆H₄NO₂). The corresponding [Au(p-C₆H₄NO₂)Cl]^? reacts with PPh₃ or AsPh₃ to give mixtures containing [AuClL]. The anionic ortho-nitrophenylgold(I) complex is much more stable than its meta- or para-nitrophenyl isomers. These are thought to be the first reports of nitrophenylgold(I) complexes.     

The preparation and catalytic hydroformylation activity of some halocarbonylrhodium(I) complexes containing phosphinoalkylorganosilicon ligands

The synthesis and properties of a series of trans-halocarbonylrhodium(I) complexes containing the phosphinoalkylorganosilicon ligands Me₃SiCH₂PPh₂, Me₃Si(CH₂)₃PPh₂, and PPh₂CH₂(Me)$\text{Si(OSiMe}{}_2\text{)}{}_3\text{O}$ have been investigated. The complexes could be prepared by an exchange reaction involving RhCl(CO)(PPh₃)₂ and the organosilicon ligands or in better yields by the reaction of Rh₂Cl₂(CO)₄ with the ligands. Iodorhodium derivatives were obtained as the exclusive products in the latter reaction if a small amount of LiI was present. The catalytic activity of RhCl(CO)(PPh₂CH₂SiMe₃)₂ was similar to that of RhCl(CO)(PPh₃)₂ in the hydroformylation of hex-1-ene at 100°C and 1000 psi pressure of H₂/CO. The catalytic properties of the iodo derivatives RhI(CO)L₂ [L = Me₃SiCH₂PPh₂, Me₃Si(CH₂)₃PPh₂, and PPh₂CH₂(Me)$\text{Si(OSiMe}{}_2\text{)}{}_3\text{O}$] varied considerably, with RhI(CO)(PPh₂CH₂SiMe₃)₂ producing an unexpectedly low linear/branched aldehyde product ratio.     

Asymmetric hydrogenation of α,β-unsaturated ketones catalyzed by Ru–TPPTS–(S,S)-DPENDS complex in ionic liquids

The asymmetric hydrogenation of α,β-unsaturated ketones catalyzed by the achiral ruthenium monophosphine complex RuCl₂(TPPTS)₂ [TPPTS: P(m-C₆H₄SO₃Na)₃] modified by (S,S)-DPENDS [disodium salt of sulfonated (S,S)-1,2-diphenyl-1,2-ethylene-diamine] was investigated in ionic liquid [RMIM]Ts (1-alkyl-3-methylimidazolium p-methylphenylsulfonates, R = ethyl, butyl, octyl, dodecyl). Chemoselectivity of 100% and 75.9% ee were obtained for benzalacetone under the optimized conditions. The resulting products can be easily separated from the catalyst immobilized in ionic liquid [EMIM]Ts by extraction with n-hexane, while the catalyst can be reused seven times without the loss of catalytic activity and enantioselectivity. Especially, the addition of water can improve the performance of the catalyst.     

Ru3(CO)12/1,10-phenanthroline-catalyzed hydroformylation of styrene and acrylic esters

The Ru₃(CO)₁₂/1,10-phenanthroline-catalyzed hydroformylation of styrene under 100 atm of syngas (CO:H₂=1:1) at 120°C in DMF gives the corresponding branched and linear aldehydes in 58 and 22% yields, respectively. With the use of quinuclidine as a ligand in place of 1,10-phenanthroline in N,N-dimethylacetamide, the corresponding branched and linear oxo-alcohols were obtained in 53 and 28% yields, respectively. Hydroformylation of methyl acrylate by a catalyst system of Ru₃(CO)₁₂/1,10-phenanthroline to afford 4-methoxy-4-methyl-δ-valerolactone 1 in 31% yield, while the catalyst system of Ru₃(CO)₁₂/PPh₃ yields the open-chain aldehyde, dimethyl 2-formyl-2-methylglutarate (3), which is the precursor of lactone 1 in 18% yield.     

Platinum-mercury compounds as intermediates to mono- and di-arylplatinum(II) complexes

The reaction of HgR₂ (R = 2,5-C₆H₃Cl₂; 2,3,4- and 2,4,6-C₆H₂Cl₃; 2,3,4,5-,2,3,4,6- and 2,3,5,6-C₆HCl₄ and C₆Cl₅) with Pt(PPh₃)₃ gives the new stable compounds [(PPh₃)₂RPt(HgR)] containing PtHg bonds. When R contains an ortho chlorine atom (R = 2,5-C₆H₃Cl₂; 2,3,4-C₆H₂Cl₃ and 2,3,4,5-C₆HCl₄) refluxing xylene solutions of these compounds gives the complexes [PtR₂-(PPh₃)₂], with simultaneous precipitation of mercury. In the other cases the initial compounds are recovered unaltered. All the compounds containing the PtHg bond react readily with CF₃COOH to give a new series of compounds of formula [Pt(O₂CCF₃)R(PPh₃)₂].     

Onium Sulfates and Hydrogen Sulfates: Products of Reactions of Sulfur(IV) Oxide with Aqueous Solutions of Alkylamines and Aniline

The reaction products formed in the SO₂–L–H₂O–O₂ systems (L is n-propylamine, n-butylamine, tert-butylamine, n-heptylamine, n-octylamine, aniline) were isolated and identified as “onium” salts [n-C₃H₇NH₃]₂SO₄, [n-C₄H₉NH₃]₂SO₄, [t-C₄H₉NH₃]₂SO₄, [n-C₇H₁₅NH₃]₃SO₄(HSO₄), [n-C₈H₁₇NH₃]₃SO₄(HSO₄), and [C₆H₅NH₃]₂SO₄. The products were characterized by elemental analysis, IR and Raman spectroscopy, mass spectrometry, and thermogravimetry.     

Carbon-chain isomerization during the electrochemical fluorination in anhydrous hydrogen fluoride—a mechanistic study

The compounds i-C₄H₉SO₂F, i-C₃H₇SO₂F and cyclo-C₃H₇C(O)F have been subjected to electrochemical fluorination in anhydrous hydrogen fluoride. The resulting products were fully analyzed by NMR spectroscopy. From the reaction balances, literature data and quantum chemical calculations, a new mechanism for carbon-chain isomerization during the electrochemical fluorination (ECF) is proposed. The key step in the formation of isomeric products is believed to be a ring closure reaction involving carbo-cationic or biradical intermediates.     

A dinuclear triple bonded RuRu compound: preparation and crystal structure of μ,μ′-1,2-phenylenediimine-(N,N′)-dicarbonylbis(triphenylphosphine)diruthenium(RuRu) (I)

Reaction of [Ru{1,2-C₆H₄(NH)₂}(PPh₃)₃] (1) with CO in toluene at room temperature afforsa as one of the products the dinuclear complex syn-[Ru₂{μ-1,2-C₆H₄(NH)₂}(CO)₂(PPh₃)₂] (2). The crystal structure of 2 reveals it to be an unsaturated bimetallic species, with two Ru(CO)(PPh₃) moieties bridged by an 8e⁻ donor η²-diimine ligand in a tetrahedral-like fashion and involving a triple RuRu bond.     

Synthesis of symmetrical diarylalkyne from palladium-catalyzed decarboxylative couplings of propiolic acid and aryl bromides under water

Symmetric diarylalkynes were obtained from the decarboxylative coupling reactions of aryl bromides and propiolic acid in water solvent condition. In the presence of phase transfer surfactant C₁₈H₃₇N(CH₃)₃Cl, the catalytic system of both Pd(PPh₃)₂Cl₂/dppb and Pd(TPPMS)₂Cl₂/TPPMS afforded the desired coupled products in good yields.     

Platinum-alkyl-B(C6F5)3 (or BF3) ‘in situ’ systems as tin(II) halide-free enantioselective hydroformylation catalysts

The dialkyl/diaryl-platinum complexes (Pt(CH₃)₂(bdpp); PtPh₂(bdpp) and Pt(2-Thioph)₂(bdpp), where bdpp stands for (2S,4S)-2,4-bis(diphenylphosphino)pentane) were reacted either with B(C₆F₅)₃, BPh₃ or BF₃. In the presence of PPh₃ or carbon monoxide cationic species with a general formulae [PtR(L)(bdpp)]⁺ (L = PPh₃, CO) were formed exclusively. The ability of boron additives to provide vacant coordination site at the platinum made these systems suitable as hydroformylation catalysts. Enantioselective hydroformylation of styrene was carried out in the presence of in situ catalysts formed from Pt(alkyl/aryl)₂(bdpp) and B(C₆F₅)₃ or BF₃. Moderate e.e-s depending strongly on the structure of the catalytic precursor have been obtained. DFT/PCM calculations reveal an S_N2-type reaction mechanism for the alkyl/aryl ligand abstraction with a notably lower activation barrier for BF₃.     

Demercuriation reactions of the complexes [(PPh3)2RPtHgR′] containing platinum-mercury bonds

The compounds [(PPh₃)₂,RPtHgR′] (R = CH₃, R′= 2,5-C₆H₃Cl₂, 2,3,4- and 2,4,6-C₆H₂Cl₃, 2,3,4,5-, 2,3,4,6- and 2,3,5,6-C₆HCl₄, C₆Cl₅; R = Et, R′ = 2,5-C₆H₃Cl₂, 2,4,6-C₆H₂Cl₃; R = 2-C₆H₄Cl, R′=2-C₆H₄(CH₃)) have been prepared by the reactions of RHgR′ with Pt(PPh₃)₃, in order to study their possible use as intermediates in the preparation of diorganoplatinum complexes with different organic ligands. The dependence of J(³¹P-¹⁹⁵Pt) on slight differences in the electronic character of the ligand R′ in the series of compounds [(PPh₃)₂(CH₃)Pt-HgR′] has been studied.     

Rhodium catalyzed deuteroformylation of styrene: (E)- and (Z)-β-deuterostyrene and β,β-dideuterostyrene formation via selective β-hydride elimination from the branched alkylrhodium intermediate

Deuteroformylation of styrene in the presence of Rh₄(CO)₁₂ as a catalytic precursor was carried out at 160 atm of CO and D₂ 1/1 at two temperatures (20 and 90°C) and for times yielding partial or complete conversion. Compounds recovered from the mixture produced by reaction and partial conversion at 90°C include unlabeled styrene, (E)- and (Z)-β-deuterostyrene, C₆H₅CHCHD, and β,β-dideuterostyrene, C₆H₅CHCD₂, whereas at room temperature the styrene does not take up deuterium. These results indicate that under hydroformylation conditions the branched alkylrhodium intermediate, which affords the branched aldehyde, in part dissociates into rhodium hydride and deuterated olefin. By contrast the linear alkyl intermediate does not dissociate under the same conditions, but instead yields almost completely the corresponding aldehyde.     

Catalyzed hydroboration of nitrostyrenes and 4-vinylaniline: a mild and selective route to aniline derivatives containing boronate esters

Transition metal catalyzed reactions of catecholborane (HBcat; cat = 1,2-O₂C₆H₄) with β-nitrostyrene and 3-nitrostyrene lead to products derived from competing hydrogenation and hydroboration of the alkene unit along with reduction of the nitro group. Hydroboration of 4-vinylaniline gave regioselective formation of either the branched or the linear organoboronate ester depending upon the catalyst precursors (i.e., RhCl(PPh₃)₃ or Rh(acac)(dppe) vs [Cp^∗IrCl₂]₂) used to facilitate this reaction. Hydroboration products were converted to air-stable primary amines by addition of pinacol.     

Catalytic activity and visible spectroscopy of [Rh(norbornadiene)Cl]2/p-RC6H4)3P system in methanol

Summary The catalytic hydrogenation of hex-1-ene in methanolic solution with [Rh(norbornadiene)Cl]₂/(p-RC₆H₄)₃ P (R=H, Me or OMe) systems preparedin situ has been measured. The catalytic activity shows a dependence on the ageing of the catalyst precursor solution in the presence of air. A spectroscopic study (visible region) has been carried out for the system with triphenyl phosphine and shows degradation with the formation of [Rh(norbornadiene)PPh₃Cl] as an intermediate. It was demonstrated that the spectral changes and the consequent catalytic activity are due to PPh₃ loss because of the oxygen dissolved in the media.