Molecular and crystal structure of rel-(4R,6R)-5-thio-5-phenyl-2,4,6-triisopropyl-1,3,5-dioxaphosphorinane

Conclusions The stereoisomer of 5-thio-5-phenyl-2,4,6-triisopropyl-1,3,5-dioxaphosphorinane with mp 124°C has twist conformation with equatorial substituents at C⁴ and C⁶ and a pseudoequatorial phenyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1056–1060, May, 1984.     

Oxidation of triphenylantimony with 4-hydroperoxy-2-hydroxy-3,4,6-triisopropylcyclohexa-2,5-dienone or 3,4,6-triisopropyl-1,2-benzoquinone

According to the NMR spectroscopic data, the oxidation of triphenylantimony with 4-hydroperoxy-2-hydroxy-3,4,6-triisopropylcyclohexa-2,5-dienone involves three steps. The first step affords the 2,4,10,12-tetraoxa-3,11-distibatricyclo[11.3.1.1^5,9]octadecatetraene derivative. The latter is rearranged into benzodioxastibolone derivatives followed by the rearrangement into 4,6,7-triisopropyl-2,2,2-triphenyl-1,3,2-benzodioxastibol-5-ol. The transformation of the latter depends on the presence of oxygen and the mode of its dosing. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1750–1757, September, 2007.     

Cp2TiCl2-catalyzed synthesis of tetraalkyl-substituted pyrazines by the reaction of nitriles with EtAlCl2 and Mg

Tetraalkyl-substituted pyrazines were obtained by the multicomponent reaction of aliphatic linear nitriles with EtAlCl₂ in the presence of Mg and Cp₂TiCl₂ catalyst in 60–91% yields. The same processing of isobutyronitrile gave 2,4,5-triisopropyl-1H-imidazole in 56% yield.     

The effective direct correlation function,an approach to the theory of liquid solutions: A new definition of the effective solute potential

A Mayer graph analysis of the solute effective direct correlation function c₀₀^eff(1,2) for a binary fluid mixture is presented. The function c₀₀^eff(1,2) is defined in terms of the solute pair correlation function h₀₀(1,2) by a one-component effective Ornstein-Zernike relation. The graphical series for c₀₀^eff(1,2) is shown to be identical to the series for the direct correlation function of a pure fluid except that pure fluid f-bonds are replaced by effective f-bonds f₀₀^eff(1,2) which exactly include the effects of solvent-solute interaction. An effective solute-solute potential W₀₀(1,2) is defined by the relation f₀₀^eff(1,2) = exp[-βW₀₀(1,2)] - 1. A graphical series for W₀₀(1,2) is presented. This single effective solute pair potential plays a role in the present formulation analogous to the role the infinite set of n-particle solute potentials plays in the McMillan-Mayer theory.     

A new oxamato-bridged heterotrinuclear NiIICuIINiII complex: synthesis,structure and properties

A new oxamato-bridged Ni^IICu^IINi^II species, [Ni(iprtacn)]₂[Cu(pba)(H₂O)_0.5](BPh₄)₂ (1), (iprtacn?=?1,4,7-triisopropyl-1,4,7-triazacyclononane; pba?=?1,3-propylenebis(oxamato)) has been synthesized and structurally as well as magnetically characterized. Complex 1 has a discrete trinuclear Ni^IICu^IINi^II structure: Two nickel(II) ions are bridged by [Cu(pba)]^2? with the macrocyclic ligand iprtacn a terminal ligand of nickel(II). Fitting the magnetic data of 1 led to g _Cu?=?2.16, g _Ni?=?2.18, J?=??112.5?cm^?1, D?=?±7.78?cm^?1. The irregular spin state structure and interaction of complex 1with DNA are described here.     

1,2-Dichlorobenzene affects the formation of the phosphoenzyme stage during the catalytic cycle of the Ca<Superscript>2+</Superscript>-ATPase from sarcoplasmic reticulum

Background

1,2-Dichlorobenzene (1,2-DCB) is a benzene-derived molecule with two Cl atoms that is commonly utilized in the synthesis of pesticides. 1,2-DCB can be absorbed by living creatures and its effects on naturally-occurring enzymatic systems, including the effects on Ca²⁺-ATPases, have been poorly studied. Therefore, we aimed to study the effect of 1,2-DCB on the Ca²⁺-ATPase from sarcoplasmic reticulum (SERCA), a critical regulator of intracellular Ca²⁺ concentration.

Results

Concentrations of 0.05–0.2 mM of 1,2-DCB were able to stimulate the hydrolytic activity of SERCA in a medium-containing Ca²⁺-ionophore. At higher concentrations (0.25–0.75 mM), 1,2-DCB inhibited the ATP hydrolysis to ~80 %. Moreover, ATP hydrolysis and Ca²⁺ uptake in a medium supported by K-oxalate showed that starting at 0.05 mM,1,2-DCB was able to uncouple the ratio of hydrolysis/Ca²⁺ transported. The effect of this compound on the integrity of the SR membrane loaded with Ca²⁺ remained unaffected. Finally, the analysis of phosphorylation of SERCA by [γ-³²P]ATP, starting under different conditions at 0° or 25 °C showed a reduction in the phosphoenzyme levels by 1,2-DCB, mostly at 0 °C.

Conclusions

The temperature-dependent decreased levels of phosphoenzyme by 1,2-DCB could be due to the acceleration of the dephosphorylation mechanism – E₂P?·?Ca₂ state to E₂ and P_i, which explains the uncoupling of the ATP hydrolysis from the Ca²⁺ transport.

     

Kinetics of the reaction of O3 with selected benzenediols

The kinetics of the reaction of O₃ with the aromatic vicinal diols 1,2‐benzenediol, 3‐methyl‐1,2‐benzenediol, and 4‐methyl‐1,2‐benzenediol have been investigated using a relative rate technique. The rate coefficients were determined in a 1080‐L smog chamber at 298 K and 1 atm total pressure of synthetic air using propene and 1,3‐butadiene as reference compounds. The following O₃ reaction rate coefficients (in units of cm³ molecule^?1 s^?1) have been obtained: k(1,2‐benzenediol) = (9.60 ± 1.12) × 10^?18, k(3‐methyl‐1,2‐benzenediol) = (2.81 ± 0.23) × 10^?17, k(4‐methyl‐1,2‐benzenediol) = (2.63 ± 0.34) × 10^?17. Absolute measurements of the O₃ rate coefficient have also been carried out by measuring the decay of the dihydroxy compound in an excess of O₃. The results from these experiments are in good agreement with the relative determinations. Atmospheric implications are discussed. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 223–230, 2003     

Thomas–Fermi term as the simplest correction to the Weizsacker term

The nature of the correlation function G(1,2) appearing in the definition of the reduced first order density operator γ′(1,2) = ρ(1)^1/2ρ(2)^1/2G(1,2) is analyzed. It is shown that when G(1,2) is expanded in terms of plane waves in the context of a single-determinant approximation to the wave function, the correction to the Weizsacker term in the kinetic energy density expression is the Thomas–Fermi term.     

Formation of a Stable Cationic Hydridodimethylplatinum(IV) Complex by the Reaction of Bis(μ-dimethyl sulfido)tetramethyldiplatinum(II) with Protonated 1,4,7-Triisopropyl-1,4,7-triazacyclononane. A First Example of Oxidative N-H Addition to a Platinum(II) Complex

The complex bis(-dimethyl sulfido)tetramethyldiplatinum(II) reacts with 1,4,7-triisopropyl-1,4,7-triazacyclopropanone (L) over the course of 24 h at room temperature in THF-d ₈ to give [PtMe₂(L)] and PtMe₂(SMe₂)₂. Subsequent addition of 1 mol of trifluoromethanesulfonic acid results in immediate formation of a previously unknown stable cationic complex [PtMe₂H(L)]⁺SO₃CF₃ ^-. This product can also be prepared by oxidative addition of the N-H bond of LH⁺SO₃CF₃ ^- to the starting complex, which points to a higher basicity of the platinum atom in [PtMe₂(L)] compared with the nitrogen atom in the ligand L. The pK _a of the cationic hydride of platinum(IV) was estimated.     

Position of the equilibrium of stereoisomers in 5-chloro-2,4,6-triisopropyl-1,3,5-dioxaphosphorinane and its derivatives

Conclusions In equilibrated 5-chloro-2,4,6-triisopropyl-1,3,5-dioxaphosphorinane and its oxide and sulfide, the stereoisomer with an axially oriented P-Cl bond predominates.Translated from Izvestiya Akademii Nauk SSSR, No. 2, pp. 420–424, February, 1983.     

Formation of O(3P) atoms and epoxides from the gas- phase reaction of O3 with isoprene

The formation yields of 1,2-epoxy-2-methyl-3-butene and 1,2-epoxy-3-methyl-3-butene have been measured from the reaction of O₃ with isoprene at room temperature and one atmosphere total pressure of N₂ and air diluents, with and without cyclohexane to scavenge the OH radicals formed in this reaction system. In addition, a relative rate method was used to determine a rate constant for the gas-phase reaction of O₃ with 1,2-epoxy-2-methyl-3-butene of (2.5 ± 0.7) x 10^-18 cm³ molecules^-1 s^-1 at 296 ± 2 K. Our data show that the epoxide yields in N₂ and air diluents are the same, with formation yields of 1,2-epoxy-2-methyl-3-butene of 0.028 ± 0.007 and of 1,2-epoxy-3-methyl-3-butene of 0.011 ± 0.004. These data further show that the epoxides arise from the primary O₃ reaction with isoprene, and not via the formation of O(³P) atoms from the O₃ - isoprene reaction followed by reaction of these O(³P) atoms with isoprene.     

First synthesis of (1,2-C2)-monolignol glucosides

The monolignol glucosides (1,2-¹³C₂)-p-glucocoumaryl alcohol, (1,2-¹³C₂)-coniferin and (1,2-¹³C₂)-syringin, and the glucosides of (1,2-¹³C₂)-p-coumaric, (1,2-¹³C₂)-ferulic and (1,2-¹³C₂)-sinapic acids were synthesized by condensation of the corresponding aldehydes with (1,2,3-¹³C₃)-malonic acid. The free acids were converted to the acyl chlorides prior to their reduction to alcohols.     

Fate of the Oxygen Atoms in the Diol‐Dehydratase‐Catalyzed Dehydration of meso‐Butane‐2,3‐diol

¹⁸O‐Substituted propane‐1,2‐diols and meso‐butane‐1,2‐diols were synthesized and fed to growing cells of Lactobacillus brevis. Propan‐1‐ol and butan‐2‐ol, prepared from such diols through diol‐dehydratase‐catalyzed dehydration followed by intracellular reduction, were analyzed for their ¹⁸O‐content. For each propane‐1,2‐diol enantiomer, partial retention or complete loss of the isotope appeared to be related to the mode of substrate binding. Specific retention of the O‐atom linked to the (R)‐configured C‐atom of meso‐butane‐1,2‐diol indicates that the diol dehydratase handles this substrate like (R)‐propane‐1,2‐diol.     

The insertion of sulfur and selenium into the 1,2-dihydrophosphete ring

Sulfur and selenium react with a 1,2-dihydrophosphete P-W(CO)₅ complex at ca. 120°C to give the corresponding 2,5-dihydro-1,2-thiaphosphole and 2,5-dihydro-1,2-selenaphosphole complexes, respectively. These products result from an insertion of S or Se into the P C sp³ bond of the four-membered ring.     

Rate coefficients for the gas‐phase reaction of OH radicals with selected dihydroxybenzenes and benzoquinones

Rate coefficients have been determined for the gas‐phase reaction of the hydroxyl (OH) radical with the aromatic dihydroxy compounds 1,2‐dihydroxybenzene, 1,2‐dihydroxy‐3‐methylbenzene and 1,2‐dihydroxy‐4‐methylbenzene as well as the two benzoquinone derivatives 1,4‐benzoquinone and methyl‐1,4‐benzoquinone. The measurements were performed in a large‐volume photoreactor at (300 ± 5) K in 760 Torr of synthetic air using the relative kinetic technique. The rate coefficients obtained using isoprene, 1,3‐butadiene, and E‐2‐butene as reference hydrocarbons are k_OH(1,2‐dihydroxybenzene) = (1.04 ± 0.21) × 10⁻¹⁰ cm³ s⁻¹, k_OH(1,2‐dihydroxy‐3‐methylbenzene) = (2.05 ± 0.43) × 10⁻¹⁰ cm³ s⁻¹, k_OH(1,2‐dihydroxy‐4‐methylbenzene) = (1.56 ± 0.33) × 10⁻¹⁰ cm³ s⁻¹, k_OH(1,4‐benzoquinone) = (4.6 ± 0.9) × 10⁻¹² cm³ s⁻¹, k_OH(methyl‐1,4‐benzoquinone) = (2.35 ± 0.47) × 10⁻¹¹ cm³ s⁻¹. This study represents the first determination of OH radical reaction‐rate coefficients for these compounds. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 696–702, 2000     

A linear rod-packing coordination polymer constructed from a non-linear dicarboxylate and the [Zn4O]6+ cluster

A 1-D coordination polymer, [Zn₄O(1,2-BDC)₃]_n (1,2-BDC?=?1,2-benezendicarboxyate), has been synthesized under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction. The coordination polymer contains [Zn₄O]⁶⁺ clusters with a central μ₄-oxygen tetrahedrally coordinated by four Zn²⁺ ions, which stack into a linear rod connected by 1,2-BDC units.     

Influence of the Metal Ions on the Allylic Rearrangement Reaction of 3,4,5,6‐Tetrahydrophthalic Anhydride

To further investigate the influence of metal ions on the allylic rearrangement of 3,4,5,6‐tetrahydrophthalic anhydride during the hydrothermal reaction, metal ions such as manganese(II), zinc(II) and cadmium(II) have been employed in the synthesis, which leads to the formation of three new lamellar coordination polymers, [Mn^II₅(µ₃‐OH)₃(1‐chec)(1,2‐chedc)(2,3‐chedc)₂(H₂O)] ( 3Mn) , [Zn^II₅(µ₃‐OH)₃(1‐chec)(1,2‐chedc)(2,3‐chedc)₂(H₂O)] ( 4Zn ), and [Cd^II₃(µ₃‐OH)₂(1,2‐chedc)₂] ( 5Cd) (1‐chec=cyclohexene‐1‐carboxylate, 1,2‐chedc=cyclohexene‐1,2‐dicarboxylate, 2,3‐chedc=cyclohexene‐1,2‐dicarboxylate). Interestingly, the allylic rearrangement reaction is metal‐dependent, which occurs only in 3Mn and 4Zn , resulting in the formation of one chiral carbon atom of the corresponding dicarboxylate ligands in both compounds. In addition, the magnetic property of compound 3Mn was studied, which revealed strong antiferromagnetic interactions between the metal centers.     

Kinetics of protonation of the 1,2-dinitrobenzene radical anion and dianion by phenol

The kinetics of protonation of electrochemically generated 1,2-dinitrobenzene (1,2-DNB) radical anions and dianions by phenol in DMF was studied by chronoamperometry. In the presence of phenol, the rate-determining step of electroreduction at the first wave potentials is the protonation of the 1,2-DNB radical anion with a rate constant of 103±13 L mol^s-1 s^s-1. The number of electrons involved in the process with phenol excess is 3, which corresponds to the formation of azoxy compounds. At the second wave potentials under these conditions, the electroreduction process is four-electron, which corresponds to the formation of 2-nitrophenyl-hydroxylamine, The rate constant for 1,2-DNB dianion protonation is 265±60 Lmol^s-1 s^s-1. The comparison of the experimental data with the results of quantum chemical calculation suggests the orbital control of the protonation reaction.     

1,2-γ3 Azaphosphinine by flash vacuum thermolysis.

1,2-γ³ Azaphosphinine 4 is prepared for the first time by flash vacuum thermolysis of 1-tert.octyl 2-phenyl 1,2-dihydro 1,2-γ³ azaphosphinine. The reaction of 4 with water gives the 1,2-dihydro 1,2-γ5 azaphosphinine 2-oxide.     

1H, 13C and 15N NMR spectra of [1,2-15N2]pyrazole derivatives

The chemical shifts and coupling constants of [1,2-¹⁵N₂]pyrazole, 2-(1-[1,2- ¹⁵N₂]pyrazolyl)-2-[l,3-²H₆]propanol, 1-nitro[1,2¹⁵N₂] and 3-nitro[1,2-¹⁵N₂]pyrazole are reported.