Design of postmetallocene catalytic systems of arylimine type for olefi n polymerization: XV. Synthesis of (N-Aryl)salicylaldimine ligands containing a but-3-enyloxy group and their complexes with titanium(IV) dichloride

A series of (N-aryl)salicylaldimines was synthesized by the reaction of salicylaldehydes substituted in the positions 3 and 5 by bulky tert-butyl or α-cumyl groups with hydrochlorides of o-, m-, and p-(but-3-enyloxy) aniline in the presence of triethylamine. The obtained compounds formed by the reaction with TiCl₂(OPr-i)₂ complexes of titanium(IV) dichloride L₂TiCl₂.     

Ultrasonic speed in compressed liquid by a sing-around method

A new apparatus for the measurement of ultrasonic speed in compressed liquid was constructed. The reliability of this instrument was confirmed by measuring the speeds in pure benzene in the ranges from 283.15 to 323.15 K and pressures up to near freezing pressure, and by comparing the results with literature values. The isentropic compressibilities κ_S were also determined using the experimental speeds and densities, and the results κ_S(u) were compared with those observed directly elsewhere κ_S(d) and those calculated thermodynamically κ_S(c) from (p, V_m, T). At atmospheric pressure, the present results, while agreeing with κ_S(u) reported in the literature, show differences from κ_S(d) and κ_S(c), while those for higher pressures close on a simple curve with κ_S(c).     

Thermal [2 + 2] cyclodimerisation of strained olefins. Cis,trans-1,5-cyclo-octadiene and trans-cyclo-octene

The title reaction in the absence of catalysts has been investigated both with the racemic and with the optically active cycloolefins. Both title olefins form [2 + 2] dimers of the trans double bonds with complete retention of configuration (trans-syn-trans2 by R + S and trans-anti-trans3 by R + R combination) and with mono-inversion (cis,trans4, both by R + S and R + R combinations), but almost none with di-inversion (cis-syn-cis5 and cis-anti-cis6), together with trans-cis isomerised starting olefins.     

The synthesis of chiral β-ketosulfoxides by enantioselective oxidation and their stereocontrolled reduction to β-hydroxysulfoxides

Various chiral non-racemic β-ketosulfoxides, a class of compounds frequently used in asymmetric synthesis, were prepared in good yields by tert-butyl hydroperoxide oxidation of the corresponding sulfides in the presence of a complex between titanium and (S,S)-hydrobenzoin. The ee values of almost all of the purified products were >98%. As ascertained by X-ray analysis and/or by NMR spectroscopy, the use of the (S,S)-form of the ligand led to aryl β-ketosulfoxides with (R_S)-configuration and to methyl phenacyl sulfoxide with the (S_S)-configuration. Some of the aryl ketosulfoxides were subjected to reduction with DIBAL-H/ZnCl₂ and the corresponding β-sulfinylalcohols with an (R,R_S)-configuration produced.     

Kinetics and mechanism of the liquid-phase oxidation of tert-butyl phenylacetate

The oxidation of tert-butyl phenylacetate in ortho-dichlorobenzene at 140°C occurs with short chains. The primary nonperoxide reaction products (tert-butyl α-hydroxyphenylacetate, tert-butyl α-oxophenylacetate, and benzaldehyde) are formed by the decomposition of a hydroperoxide (tert-butyl α-hydroperoxyphenylacetate) and (or) by the recombination of peroxy radicals with and without chain termination. Benzaldehyde and tert-butyl α-hydroxyphenylacetate undergo radical chain oxidation in a reaction medium to result in benzoic acid and tert-butyl α-oxophenylacetate. Homolytic hydroperoxide decomposition is responsible for process autoacceleration and results in benzaldehyde, which is also formed from hydroperoxide by a nonradical mechanism, probably, via a dioxetane intermediate. Both of the reactions are catalyzed by benzoic acid. Benzoic acid has no effect on hydroperoxide conversion into tert-butyl α-oxophenylacetate, which most likely occurs as a result of hydroperoxide decomposition induced by peroxy radicals. The rate constants of the main steps of the process and kinetic parameters have been calculated by solving an inverse kinetic problem.     

Hydrothermal Synthesis and Crystal Structure of the First Ammonium Indium(III) Phosphate NH4In(OH)PO4 with Spiral Chains of InO4(OH)2

An ammonium indium hydrogen phosphate, NH₄In(OH)PO₄, was synthesized under mild hydrothermal conditions, and the crystal structure was characterized by single-crystal X-ray diffraction method. The compound crystallizes with the RbIn(OH)PO₄ type with the following data: M_r=244.84, tetragonal, tP104, P4₃2₁2 (No.96), a=9.416(2) Å, c=11.159(3) Å, V=989.9(3) ų, Z=8, D_x=3.288 g cm⁻³, λ=0.71073 Å, μ=50.34 cm⁻¹, F(000)=928, T=293 K, R1=0.0606, wR2=0.1472 for 91 variables and 1813 contributing unique reflections. The structure is characterized by chiral InO₄(OH)₂ chains along the c axis formed by sharing OH corners. The chains are isolated by PO₄ tetrahedra leading to a three-dimensional framework structure with channels occupied by NH₄⁺ ions. The framework structure is similar to that of KIn(OH)PO₄ and γ-NaTiOPO₄. The hydrogen bonds formed by NH₄⁺ with the polyhedral oxygen atoms play an important role in the anisotropic changes of the lattice with respect to its alkali metal analogues. The topological construction of the title structure can be considered as an augmented 4,6-net with larger porosity.     

(R)- and (S)-3-Hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone as chiral auxiliaries in the enantioselective preparation of α-aryloxypropanoic acid herbicides and α-chlorocarboxylic acids

rac-α-Chlorocarboxylic acids, rac-9a–e, were formally deracemized by reaction of the corresponding acyl chlorides with the chiral auxiliaries (R)- and (S)-3-hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone, (R)- and (S)-4, followed by mild alkaline hydrolysis. The highest o.p. (99%) was obtained in the case of (S)-α-chloropropanoic acid, a known precursor for the synthesis of (R)-α-aryloxypropanoic acid herbicides such as dichlorprop-P, (R)-3a, or mecoprop-P, (R)-3b, which, together with their enantiomers, were also obtained in moderate e.e.s by dynamic kinetic resolution from (αRS,3S)-4,4-dimethyl-2-oxo-1-phenylpyrrolidin-3-yl α-bromopropanoate, (αRS,3S)-6, by reaction with the corresponding phenoxide followed by mild acid hydrolysis.     

Light scattering behaviour of low-molecular-weight polymers in mixed solvents with very high selective sorption

Some low-molecular-weight polymers (poly(butyl methacrylate), nylon 6, nylon 12) in the solvent system m-cresol/n-heptane, with effective refractive index increments (?n/?c)_μ in the range 0.34?0.81 ml/g, have been studied by light scattering. These extremely large values, measured by differential refractometry of solutions in the state of dialysis equilibrium, are mainly due to very great selective sorption of one solvent component (m-cresol) on the polymers studied. The effect inherent to these systems, viz. that of the free solvent composition change, has been discussed and exemplified by the light scattering behaviour of solutions of oligomers of butyl methacrylate. The light scattering anomalies observed with solutions of some nylons in m-cresol/n-heptane have been interpreted as due to interaction of polymer end-groups. It has been demonstrated that the determination of $\text{M}{}_{\mathrm{w}}$ of the order of 10³ by light scattering in systems with large (?n/?c)_μ values, i.e. with large scattering power, is possible with good accuracy.     

Mixed oxides of sodium, antimony (5+) and divalent metals (Ni, Co, Zn or Mg)

A family of α-NaFeO₂-type oxides Na_xM_(1+x)/3Sb_(2−x)/3O₂ (M=Ni, Co, Zn, Mg; x≈0.8 or 0.9) has been prepared by solid state reactions and characterized by powder XRD. At x=1, ordering occurs with tripling the unit cells and formula units. The powder patterns for Na₃M₂SbO₆ (M=Ni, Co) comply with both trigonal P3₁12 cell and monoclinic C2/m cell. The Ni compound exhibits also a series of extremely weak reflections (I<0.3%) that need doubling of the c axis, and the final cell is C2/c, a=5.3048(3), b=9.1879(4), c=10.8356(7), β=99.390(5). These ambiguities are explained by stacking faults. The compounds absorb atmospheric moisture with c-axis expansion up to 29%. A delafossite-related superlattice Ag₃Co₂SbO₆ has been prepared by ion exchange and refined: P3₁12, a=5.3842(2), c=18.6613(10). Ionic conductivity of the Na_0.8Ni_0.6Sb_0.4O₂ ceramics, 0.4 S/m at 300 °C, is greater than reported previously, presumably owing to the grain orientation produced by hot pressing.     

Synthesis of polypyrrole–polycaprolactone composites by emulsion polymerization and the electrorheological behavior of their suspensions

Polypyrrole–polycaprolactone (PPy-PCL) composites were synthesized by emulsion polymerization to improve their mechanical and electrical properties by forming conducting polymer composites and hence enhance the electrorheological (ER) response. Various PPy-PCL composite particles were synthesized by controlling the amount of PCL. The ER response increased with increasing electric field strength and particle volume fraction. A power-law dependence, τ?=?Kφ ^m E ⁿ , showed a good fit to the yield stresses when m?=?2 and n?=?1.5. The dependence of E ^1.5 is consistent with the conduction model and the dependence of φ ² appears to be related to structural changes with the electric field, which leads to many-body interactions between the particles. The ER response also increased with increasing amount of PCL, but the dielectric properties and dc conductivities of the PPy-PCL composite particles and the dielectric properties of the PPy-PCL composite suspensions were not consistent with the ER behavior. However, the particle diameter increased with the increasing amount of PCL, which is consistent with the ER behavior. The ER behavior of various amounts of PCL fits τ?=?85.12d ⁴ E ^3/2 quite well. The proportionality of d ⁴ appears to be due to the many-body interactions between the particles.     

Topological and thermodynamic investigations of molecular interactions in binary mixtures: Molar excess volumes and molar excess enthalpies

Molar excess volumes and molar excess enthalpies of butyl acetate (i) with cyclohexane or benzene or toluene or o-, m- or p-xylene (j) binary mixtures have been measured dilatometrically and calorimetrically over the entire composition range at 308.15 K. The observed data have also been analyzed in terms of graph theoretical approach. The analysis of V^E data by graph theoretical approach suggests that butyl acetate in pure state exists as associated entity and (i + j) mixtures are characterized by the presence of (i–j) molecular entity. It has further been observed that V^E and H^E values calculated by this approach agree well with the corresponding experimental values. The presence of molecular entity is further confirmed by IR study of (i + j) mixture.     

A concise and stereospecific synthesis of some cyclitols containing eight-membered rings: cyclooctane-1,2,3,4-tetraoles

A concise and efficient synthesis of cyclooctane-1,2,3,4-tetraoles, new polyhydroxylated eight-membered carbocycles, is described starting from cis,cis-1,3-cyclooctadiene. Cyclooctene endoperoxide obtained by photooxygenation of cis,cis-1,3-cyclooctadiene was the key compound in the synthesis. Reduction of the endoperoxide with zinc or thiourea followed by acetylation of the hydroxyl group and OsO₄/NMO oxidation of the double bond gave (1R(S),2S(R),3R(S),4S(R))-cyclooctane-1,2,3,4-tetraol. Interestingly, epoxidation of cyclooctene-1,4-diol with m-CPBA also afforded trans-epoxy-diol 17. (1R(S),2R(S),3R(S),4S(R))-cyclooctane-1,2,3,4-tetraol was easily obtained by hydrolysis of epoxy-diol 17.     

Synthesis and properties of BCOD-fused trithiasapphyrin and trithiabenzosapphyrins

Bicyclo[2.2.2]octadiene(BCOD)-fused trithiasapphyrin was prepared by 3+2 condensation of BCOD-fused thiatripyrrane with BCOD-fused bithiophene. The BCOD-fused trithiasapphyrin was successfully converted to pentabenzo[b,g,l,q,v]sapphyrin by the thermal retro-Diels-Alder reaction. In this case, trithiapentabenzo[b,g,l,q,v]- and trithiadibenzo[g,q]sapphyrins were selectively prepared by control of the temperature in the thermal retro-Diels-Alder reaction.     

Efficient access to β- and γ-carbolines from a common starting material by sequential site-selective Pd-catalyzed C–C,C–N coupling reactions

Two efficient and practical approaches are reported for the synthesis of β- and γ-carboline derivatives from 3,4-dibromopyridine as a common starting material. The β-carbolines were prepared by site-selective Pd-catalyzed C–C coupling with o-bromophenylboronic acid and subsequent cyclization by double C–N coupling with amines. γ-Carbolines were prepared from the same starting material by C–N coupling with anilines and subsequent annulation by domino C–C/C–N coupling with o-bromophenylboronic acid.     

Preparing β-blocker (R)-Nifenalol based on enantioconvergent synthesis of (R)-p-nitrophenylglycols in continuous packed bed reactor with epoxide hydrolase

An engineered epoxide hydrolase from Vigna radiate (VrEH2_M263N) shows near-perfect enantioconvergence in single enzyme mediated hydrolysis of racemic p-nitrostyrene oxide (pNSO). To explore industrial potential of the promising biocatalyst, we tried to immobilize the VrEH2 variant by covalently linking onto a commercially available amino resin ECR8405F. Then a 5-mL packed bed reactor filled with the immobilized VrEH2_M263N was connected with macroporous resin NKA-11 for in situ product adsorption, and the product (R)-p-nitrophenyl glycol (pNPG) was harvested by methanol elution, with 91% isolated yield and 97% ee. The continuous reactor was operated stably for more than 100?h with a space time yield of 20?g?L^?1?h^?1. Subsequently, the β-blocker (R)-Nifenalol was prepared by chemically synthesized from (R)-pNPG, affording the product in an overall yield of 61.3% (1.5?g) and an enantiopurity of 99.9% ee after recrystallization.     

The preparation and structure of the tetranuclear ruthenium cluster [Ru4(CO)10(μ2-Cl)2(μ3-OEt)2]

The tetranuclear ruthenium cluster [Ru₄(CO)₁₀Cl₂(OEt)₂] has been prepared in low yield by the reaction of [Ru₃(CO)₁₂] with [N(PPh₃)₂]Cl in refluxing EtOH, followed by oxidation with either [NO][BF₄] or Ag[ClO₄]. A single-crystal X-ray analysis of the complex shows that the four metal atoms adopt a planar geometry with one ruthenium bonded by two μ₂-Cl ligands and two μ₃-OEt ligands to a trinuclear fragment. This complex crystallises in the monoclinic space group I2/c, with a 14.458(3), b 22.073(6), c 15.302(4) Å, β 99.54(2)°, Z = 8; 3113 observed data with F > 3σ(F) were refined by blocked full-matrix least squares to R = 0.031, R_w = 0.034.     

Residual photocurrent at a mercury electrode

The residual photocurrent observed at negative potentials with mercury in contact with slightly alkaline 1 M KCl solution has been reinvestigated and found to be caused partly by the reaction of e^?_aq with traces of unidentified electron acceptors and partly by reaction with the solvent. Such a solution can be freed from electron-accepting impurities by irradiation with light of shorter wavelength than 270 nm if SO^2?₃ is present at low concentration. The time constant for the homogeneous decay of e^?_aq at pH ca. 8.8 is then raised to about 400 μs. This slow decay is due to reaction with the solvent as the decay time constant can be increased considerably by raising the pH of the solution. In unsteady state experiments with purified 1 M KCl solutions of high pH containing no added scavenger for e^?_aq the current connected with electron emission and e^?_aq diffusion towards the electrode and the bulk of the solution, is cancelled out at ca. ?1.4 V vs. SCE by a thermal non-faradaic current component when 360 nm light is employed. When CO₂ is present at high concentration a similar cancellation is observed at lower pH at ca. ?1.1 V vs. SCE, suggesting a value for the diffusion coefficient of the radical-ion CO^?₂ about 3.3 times smaller than that of e^?_aq.     

A facile,one-pot synthesis of Ephedra-based aziridines

A series of enantiomerically and diastereomerically enriched N-sulfonylaziridines have been prepared by a single-pot process from (1R,2S)- and (1S,2R)-norephedrine and (1S,2S)-pseudonorephedrine. The cyclization process involved N-sulfonylation of the Ephedra alkaloid followed by O-sulfonylation with methanesulfonyl chloride. The bis(sulfonyl)Ephedra derivatives were treated with either hydrazine or sodium hydroxide to afford the N-sulfonylaziridines.     

Defective disordered crystal structure of (2-hydroxyphenyl)diphenylphosphineoxide

A disordered defective crystal structure of (2-hydroxyphenyl)diphenylphosphineoxide (I) has been studied by XRD method. The rhombic structure of I (space group Pna2₁, a = 18.271 Å, b = 8.337 Å, c = 19.629 Å, Z = 8) was solved by a direct method and refined by a full-matrix LSM having taken into account its crystal packing defects (by introducing two additional independent low-populated molecules) to R = 0.060 for all 3517 independent reflections measured (a CAD-4 autodiffractometer, λMoK _α. There are two independent molecules A and B with population 0.90 and two additional independent molecules C and D with population 0.10 in the structure of I.