Search

Hydrosilylation of allyl ethyl, allyl butyl, allyl glycidyl, allyl benzyl, and allyl phenyl ethers by 1,1,3,3-tetramethyldisiloxane in the presence of supported sulfur-containing platinum(II) complexes with the general formula [{SiO2}O2Si(Me)(CH2)3SR]2PtCl2 (R = Bu, Hex, Bn; {SiO2} is silica surface) and side processes have been studied.

Composite fibers were obtained from highly concentrated solutions of cellulose and polyacrylonitrile (PAN) copolymers in N-methylmorpholine-N-oxide (MMO). The processes of co-dissolving cellulose and PAN in MMO and the rheological properties of the resulting composite solutions were examined. It was shown that introduction of PAN into the cellulose matrix affects the structurization processes. Specifically, an increase of the PAN content in the cellulose matrix affects the thermal behavior and mechanical properties of the composite fibers.

Dehydrocondensation reactions of silicon hydrides catalyzed by the rhodium(III) complex [RhCl3(Me2SO)3] in the absence of the second substrate were studied. It was found that the complex [RhCl3(Me2SO)3] catalyzed the dehydrocondensation reaction with the formation of compounds containing siloxane bonds. Analysis of NMR spectra has shown that the reaction of [RhCl3(Me2SO)3] with silicon hydride includes sequential desoxygenation of sulfoxide ligands to sulfide ligands with the complex [RhCl3(Me2S)3] formation.

2-Aryl- and 2-furyl-4-carboxy-1,3-thiazolidines were synthesized. Their spectral properties were studied, and conformational analysis was performed. It was shown that they exist in solution as an equilibrium of neutral and zwitter-ion forms. The influence of the nature of substitutents and of their location in a benzene ring of thiazolidines as ligands of rhodium complexes on acetophenone hydrosilylation with diphenylsilane was examined. Thiazolidines containing donor substituents in the para-position of the benzene ring were found to be the most effective; maximal asymmetrical induction (55% ee) was reached in the presence of 2-(4-methoxyphenyl)-4-carboxy-1,3-thiazolidine.

Synthesis was carried out of the new mixed-ligand square-planar platinum(II)complexes {Pt(R2SO)[(-)-S-NOBIN]Cl2}, where (-)-S-NOBIN was S-2-amino-2′-hydroxy-1,1′-binaphthyl (R = Me, Et). The complexes are of interest as catalysts for asymmetrical synthesis. The detailed analysis of NMR, UV, and CD spectra of these compounds was performed. These complexes were established to be a mixture of the corresponding cis- and trans-isomers.

A preparative method of synthesis of optically pure S-2-amino-2′-hydroxy-1,1′-binaphthyl (S-Nobin), the precoursor in the synthesis of other asymmetric 1,1-binaphthyls applied as the ligands at the creation of the catalysts of asymmetric synthesis, is modified. The UV and CD spectra of this compound were studied in detail and essential dependence of spectral information on the solvent nature was shown.

Synthesis of the combined ligand complex of copper(II) prolinate bis(1,5-pentamethylenetetrazole) [Cu(PMT)2](Pro)2 was carried out. The product is interesting as a biologically active compound. It is obtained by reaction of copper carbonate with proline followed by further reaction with corazole. The composition and structure of the complex were confirmed by elemental analysis and data of UV, IR, and 1H NMR spectroscopy. The complex was characterized in detail by the method of circular optical dichroism.

Interaction of allyl ethers with hydrosiloxanes in the presence of metal complexes has been investigated by spectral methods (1H NMR, IR, and GC-MS) as well as by gas-liquid chromatography. It has been shown that the anti-Markovnikov addition predominantly occurs in the studied cases; disproportionation of siloxanes and migration of double bond in the ethers have been identified as side reactions. The tendency to enter the side reactions has decreased in the following series: (HMeSiO)4 > HMe2Si(OSiMe2)2H ≈ HMe2SiOSiMe3 > (HMe2Si)2O > (Me3SiOSiMeH)2O. The general scheme of disproportionation of siloxanes HMe2Si(OSiMe2) n H (n ≥ 1) has been proposed. According to mass spectrometry data, the silicon-containing fragment majorly contributes to the fragmentation of hydrosilylation products. Fragmentation of the γ,γ-adducts is similar to that of γ-adducts. The predominant direction of fragmentation in the products of β,γ-addition of HMe2Si(OSiMe2)nH (n = 1–3) to allyl ethers is determined by fragmentation of the γ-component of the molecule. The scheme of fragmentation of the hydrosilylation products ions has been proposed.

New chiral rhodium complexes cis-[Rh(CO)2(RNH2)Cl] [RNH2 = (R)-(−)-cis-MyrtNH2, (R)-(−)-MenthylNH2, (R)-(+)-BornylNH2] were synthesized and their catalytic properties in reactions of hydrosilylation of acetophenone with diphenylsilane were studied. It was shown that the reaction products were diphenyl-1-phenylethoxysilane, diphenyl-1-phenylvinyloxysilane and 1,1,3,3-tetraphenyldisiloxane. The best catalytic activity displayed (−)-cis-[Rh(CO)2(MenthNH2)Cl]. The hydrosilylation of acetophenone with diphenylsilane in the presence of [Rh(CO)2(μ-Cl)]2 and [Rh(cod)Cl]2 and amines in situ was studied. The best ratio amine:complex = 5:1 was established. With the catalytic systems based on [Rh(cod)Cl]2 or [Rh(CO)2(μ-Cl)]2 the activity increased in the series of amines: (R)-(−)-cis-MyrtNH2 < (R)-(−)-MenthylNH2 < (R)-(+)-BornylNH2, and (R)-(−)-MenthylNH2 < (R)-(+)-BornylNH2 < (R)-(−)-cis-MyrtNH2, respectively. The chemoselectivity maximum was observed in the presence of [Rh(cod)Cl]2 with (R)-(−)-MenthylNH2 and [Rh (CO)2(μ-Cl)]2 with (R)-(+)-BornylNH2; maximum asymmetric induction was 43.5% ee at the use of [Rh(CO)2 (μ-Cl)]2 and (R)-(+)-BornylNH2.

Reaction of α-methylstyrene with 1,1,3,3-tetramethyldisiloxane in the presence of the complexes of platinum(II), palladium(II) and rhodium(I) is explored. It is established that in the presence of platinum catalyst predominantly occurs hydrosilylation of α-methylstyrene leading to formation of β-adduct, on palladium catalysts proceeds reduction of α-methylstyrene, on rhodium catalysts both the processes take place. In the reaction mixture proceeds disproportion and dehydrocondensation of 1,1,3,3-tetramethyldisiloxane that leads to formation of long chain linear and cyclic siloxanes of general formula HMe2Si(OSiMe2)nH and (-OSiMe2-)m (n = 2–6, m = 3–7), respectively. Platinum catalysts promotes formation of linear siloxanes, while both rhodium and palladium catalysts afford linear and cyclic siloxanes as well. Structure of intermediate metallocomplexes is studied.

[2-(6,6-Dimethylbicyclo[3.1.1]hept-2-enyl)ethyl]diphenylphosphine and the corresponding phosphine oxide, that hold promise as ligands in metal complex catalysis, were synthesized on the basis of (1R)-(-)-nopol. A Pd(II) bisphosphine complex is obtained on the basis of the synthesized phosphine. When the system [PdCl2(COD)]-[2-(6,6-dimethylbicyclo[3.1.1]hept-2-enyl)ethyl]diphenylphosphine oxide is used as catalyst in the reaction of cyclohexa-1,3-diene with trichlorosilane, asymmetric induction occurs.

The reaction of dialkyl hydrogen phosphites and diphenylphosphine oxide with dialkyl 2-allylmalonates in the presence of [Pd(Ph3P)4] is studied. The addition of the hydrophosphoryl compounds to the multiple bond is established to proceed by the Markovnikov rule. The reaction is accompanied by the side process of malonate dealkoxycarbonylation whose contribution to the main process depends on the nature of the reagents.

The transformations of platinum(II) and platinum(IV) complexes with inner-and outer-sphere ligands by the action of (+)-α-pinene and (+)-limonene were studied. Reduction of the metal complex is the main process whose rate increases in the following outer-sphere ligand series: (Me2SO)2H+ < Et3NH+ < K− < H+. The reaction of K2PtCl4 with α-pinene gave cis-terpine monohydrate and dichloro-η4-[p-mentha-1,8(9)-diene]platinum(II), and their structure was proved by X-ray analysis. The complex belongs to monoclinic crystal system, the Pt-Cl and Pt-C bonds therein have different lengths, the ClPtCl angle is 85.88°, and the C=C bond plane is orthogonal to the square coordination core. Dichloro-η4-[p-mentha-1,8(9)-diene]-platinum(II) was tested as catalyst in the hydrosilylation of acetophenone with diphenylsilane.

A new catalytic reaction of the competing phenylation and hydrophenylation in air of methyl acrylate with tetraphenylantimony chloride in the presence of PdCl2 (0.04 mol per 1 mol of organometallic compound) in acetonitrile at 50°C for 6 h was studied. The yields of methyl cynnamate and methyl hydrocynnamate were 0.73 and 0.27 mol mol−1 respectively. The products ratio obtained depends slightly on the process duration, the Ph4SbCl and methyl acrylate ratio, and the structure of Pd salt [PdCl2, Pd(OAc)2, Li2PdCl4], but significantly on the nature of a solvent (MeCN > DMF > THF). The use of Ph4SbCl instead of Ph4SbBr leads to decrease in the yield of methyl hydrocynnamate to 0.04 mol mol−1. In the reactions of Ph4SbX (X = F, I, OAc, O2CEt) the product is not formed at all.

Hydrosilylation of tetramethyldivinyldisiloxane with pentamethyl-and tetramethyldisiloxane in the presence of photoactivated alkene and sulfoxide platinum(II) complexes was studied. The most active photoactivated catalysts are bis-sulfoxide platinum complexes; an additional photosensitive center, the oxalate ligand, enhances the effect of photoirradiation.