Reaction of Organoelement Hydrides R<Subscript>3</Subscript>EH (E = Si,Ge) with Metal <Emphasis Type="Italic">tert</Emphasis>-Butylate (M = Al,Ti)-<Emphasis Type="Italic">tert</Emphasis>-Butyl Hydroperoxide Oxidative Systems

Trialkyl(aryl)silanes and -germanes effectively react with metal (Al, Ti) tert-butylate-tert-butyl-hydroperoxide under mild conditions (room temperature, benzene or tetrachloromethane) mainly by the element-hydrogen bond. The character of the products depends on the nature of the element, the structure of the radical bound to it, and the solvent. The process is radical in nature. It includes the stages of formation of element-centered radicals and their reaction with the oxygen generated by the system. The intermediate organometallic peroxides can also acts as oxidants for the element (Si, Ge)-hydrogen bonds.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1161–1170.Original Russian Text Copyright © 2005 by Stepovik, Gulenova, Martynova, Skvortsov, Cherkasov.     

Organomagnesium Synthesis of <Emphasis Type="Italic">sec</Emphasis>-Butyl- and <Emphasis Type="Italic">tert</Emphasis>-Alkylchlorogermanes and Their Reaction with Ethynylmagnesium Bromide

The limits of application of organomagnesium synthesis to the substitution of chlorine atoms in tetrachlorogermane with bulky alkyl groups are established. The reaction of tetrachlorogermane with 2-butylmagnesium chloride leads to the substitution of one, two, or three chlorine atoms, yielding the corresponding alkylchlorogermanes (MeEtCH)_nGeCl_4-n . The reaction of GeCl₄ with tert-alkylmagnesium halides leads to the substitution of only one chlorine atom, yielding tert-alkyltrichlorogermanes RMe₂CGeCl₃ (R = Me, Et, Bu). tert-Butyltrichlorogermane reacts with ethylmagnesium bromide to give ethyl(tert-butyl)dichlorogermane. Isopropyltrichlorogermane reacts with tert-butylmagnesium chloride to give isopropyl(tert-butyl)dichlorogermane. This shows that the organomagnesium synthesis does allow linking of two bulky substituents to the germanium atom. The reaction of tert-alkyltrichlorogermanes and 2-butyltrichlorogermane in THF with ethynylmagnesium bromide, in which the hydrocarbon group is the most sterically accessible, allows substitution of all the three chlorine atoms, yielding the corresponding alkyl(triethynyl)germanes. The latter compounds react with the Grignard reagent and trimethylchlorosilane to give the corresponding alkyl(trimethylsilylethynyl)germanes.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 5, 2005, pp. 757–761.Original Russian Text Copyright © 2005 by O. Yarosh, Voronkov, Zhilitskaya, N. Yarosh, Albanov, Korotaeva.     

Structure and intermolecular interactions of <Emphasis Type="Italic">N</Emphasis>-(3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-hydroxybenzyl)thioureas

The molecular and crystal structure and the hydrogen bonding in crystal and in solutions of N-phenyl-N-(3,5-di-tert-butyl-4-hydroxybenzyl)thiourea and N-(3,5-di-tert-butyl-4- hydroxybenzyl)thiourea were studied by single crystal X-ray diffraction and IR spectroscopy. The intermolecular interactions of these compounds are essentially different.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1864–1870.Original Russian Text Copyright © 2004 by Bukharov, Litvinov, Gubaidullin, Chernova, Shagidullin, Nugumanova, Mukmeneva.This revised version was published online in April 2005 with a corrected cover date.     

Alkylation of 2,6-di-<Emphasis Type="Italic">tert</Emphasis>-butylphenol with methyl acrylate catalyzed by potassium 2,6-di-<Emphasis Type="Italic">tert</Emphasis>-butylphenoxide

The kinetics of catalytic alkylation of 2,6-di-tert-butylphenol (ArOH) with methyl acrylate (MA) in the presence of potassium 2,6-di-tert-butylphenoxide (ArOK) depends on the method for the preparation of ArOK. The reaction of ArOH with KOH at temperatures > 180 °C affords monomeric ArOK, whose properties differ from those in the case of potassium 2,6-di-tert-butylphenoxide synthesized by the earlier methods. The regularities of ArOH alkylation depend on the ArOK concentration, the ArOH: MA ratio, and the effect of microadditives of polar solvents. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1971–1974, October, 2007.     

Synthesis of magnesium catecholate and <Emphasis Type="Italic">o</Emphasis>-semiquinone complexes by oxidation of the metal with 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-<Emphasis Type="Italic">o</Emphasis>-benzoquinone

Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL₂ (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ₂MgL_n (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et₂O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy₂]₂ and SQ₂Mg·DME complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007.     

Building up of a <Emphasis Type="Italic">peri</Emphasis>-Hydroxynaphthoyl Fragment on the Core of 2<Emphasis Type="Italic">H</Emphasis>-Naphtho[1,8<Emphasis Type="Italic">-bc</Emphasis>] furan

The reaction of 2-aryl-5-acetoxy-4,8-di-tert-butyl-2H-naphtho[1,8-bc]furan with dichloromethyl ethyl ether in the presence of aluminum chloride gave rise to 6-formyl derivatives of the title heterocyclic system, and at the use of aliphatic acids anhydrides in the presence of perchloric acid 6-acyl derivatives were obtained. The target products with a peri-hydroxycarbonyl group were obtained by the ester group elimination.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 237-242.Original Russian Text Copyright © 2005 by Tyurin, Antonov, Minyaeva, Mezheritskii.     

Functionalization of sterically hindered <Emphasis Type="Italic">o</Emphasis>-benzoquinones: amino-substituted 3,6-di(<Emphasis Type="Italic">tert</Emphasis>-butyl)-<Emphasis Type="Italic">o</Emphasis>-benzoquinones

New sterically hindered functionalized o-quinones were synthesized by the 1,4-nucleophilic addition of secondary cyclic amines to 3,6-di(tert-butyl)-o-benzoquinone. The ability of these o-quinones to form o-semiquinone complexes with transition and main-group metals was studied by ESR spectroscopy in solution. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1786–1793, September, 2007.     

Synthesis of new 1<Emphasis Type="Italic">H</Emphasis>-pyridazine derivatives <Emphasis Type="Italic">peri</Emphasis>-annelated with acenaphthene and acenaphthylene

The reaction of 6-acetyl-5-hydroxyacenaphthene with methylhydrazine afforded 1,3-dimethyl-1H-6,7-dihydroacenaphtho[5,6-de]pyridazine. Its dehydrogenation with chloranil gave 1,3-dimethyl-1H-acenaphtho[5,6-de]pyridazine, which is a heteroaromatic compound with an essentially new topology of the ρsystem. The reaction of 3-methyl-1H-6,7-dihydroacenaphtho[5,6-de]pyridazine with 3,5-di-tert-butyl-1,2-benzoquinone yielded a dimer containing the acenaphthene and acenaphthylene moieties of peri-annelated 1H-1,2-diazines connected in positions 1′ and 9.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 777–780, March, 2005.     

Micelle formation induced by photolysis of a poly(<Emphasis Type="Italic">tert</Emphasis>-butoxystyrene)-<Emphasis Type="Italic">block</Emphasis>-polystyrene diblock copolymer

We found the novel photolysis-induced micellization of the poly(tert-butoxystyrene)-block-polystyrene diblock copolymer (PBSt-b-PSt). PBSt-b-PSt with a molecular weight of Mn(PBSt-b-PSt) = 15,000-b-97,000 showed no self-assembly in dichloromethane and existed as isolated copolymers with a hydrodynamic diameter of 16.6 nm. Dynamic light scattering demonstrated that the copolymer produced micelles with a 63.0 nm hydrodynamic diameter when the copolymer solution was irradiated with a high-pressure mercury lamp at room temperature in the presence of bis(alkylphenyl) iodonium hexafluorophosphate, a photoacid generator. The ¹H NMR analysis revealed that the micellization resulted from the photolysis of the PBSt blocks into insoluble poly(vinyl phenol) blocks based on the fact that the signal intensity of the tert-butyl protons decreased over time during the irradiation. It was found that the micellization rapidly proceeded as the degree of the photolysis reached over 50% and was completed at 90%.     

ESR investigation of paramagnetic derivatives of [6-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-(5-<Emphasis Type="Italic">tert</Emphasis>-butyl-2-methyl-3,4-dioxocyclohexa-1,5-dien-1-yl)-3-methylcatecholato]triphenylantimony(V)

A number of paramagnetic derivatives of [6-tert-butyl-4-(5-tert-butyl-2-methyl-3,4-dioxocyclohexa-1,5-dien-1-yl)-3-methylcatecholato]triphenylantimony(v) were investigated by ESR spectroscopy. The reactions of this complex with Cp₂Co or LiCl in the presence of Hg_metal. lead to the formation of free (nonchelated) radical anion semiquiones. Chelated complexes are formed in the case of Tl(Hg), Mn₂(CO)₁₀, Re₂(CO)₁₀, Sn₂Ph₆, Cu(met.), and CuCl + dppfc (dppfc is bis-diphenylphosphinoferrocene). Dedicated to Academician A. L. Buchachenko on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2004–2009, September, 2005.     

Generation and IR spectra of ionic and molecular complexes of aluminum chloride with <Emphasis Type="Italic">tert</Emphasis>- and <Emphasis Type="Italic">sec</Emphasis>-butyl chlorides

Sec-butyl and tert-butyl cations were first stabilized upon cocondensation of aluminum chloride and haloalkanes (2-chlorobutane and 2-chloro-2-methylpropane, respectively) and their IR spectra and thermal stability investigated. Aluminum chloride anions participating in stabilization of carbenium ions were revealed. Ionic complexes and both 1:1 and 2:1 molecular complexes of reagents were detected and their IR spectra studied. Quantum-chemical calculations at the PBE level of density functional theory with inclusion of electron correlation were employed to optimize the geometric parameters and to determine the vibrational frequencies of aluminum chloride, butyl chlorides, and their complexes of various compositions. The structures of the associates observed were determined on the basis of comparison of the experimental and calculated vibrational spectra.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 147–155, January, 2005.     

<Emphasis Type="Italic">o</Emphasis>-Semiquinone metal complexes as derivatives of sterically hindered di-<Emphasis Type="Italic">o</Emphasis>-quinone

ESR spectroscopy was used to study a series of mono- and binuclear o-semiquinone metal complexes, viz., derivatives of sterically hindered di-o-quinone 1,2-bis(2,5-di-tert-butylcyclohexadiene-1,5-dion-3,4-yl)ethane (1). Hindered rotation was found in the o-semiquinone moiety of the generated complexes. Magnetochemical measurements for polymeric bis(o-semiquinolate)copper(II) based on di-o-quinone 1 showed two antiferromagnetic channels of interaction between the paramagnetic centers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1580–1584, July, 2005.     

Formation and structures of 2,5-di-<Emphasis Type="Italic">tert</Emphasis>-butylcyclopentadienone dimers

The structures of dimers formed from 2,5-di-tert-butylcyclopentadienone in the reaction with alkaline metals and in the Diels-Alder reaction were studied. A photochemical rearrangement with ring contraction was found for the second dimer. Spectral features of the dimers related to steric hindrance were studied by 1D and 2D NMR procedures.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2179–2183, October, 2004.     

Interaction of functionally-substituted 4-alkyl-2,6-di-<Emphasis Type="Italic">tert</Emphasis>-butylphenols with hydrohalic acids

Reactions of 4-alkyl-2,6-di-tert-butylphenols containing OH, SH, COOH, and COOMe groups in their para substituents with hydrogen chloride and hydrohalic acids were studied. One-step transformations of 2,6-di-tert-butyl-4-(ω-hydroxyalkyl)phenols to the corresponding 4-(ω-halogenoalkyl)phenols, as well as of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and its esters to phloretic acid were proposed. 4-(3-Mercaptopropyl)phenol upon heating with conc. HBr undergoes condensation to 3-(4-hydroxyphenyl)propyl 4-(3-mercaptopropyl)phenyl sulfide as the main product. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1078–1083, June, 2007.     

Synthesis of a Chiral 3,3′-Di-<Emphasis Type="Italic">tert</Emphasis>-butyl-2,2′-bipyrrole

Summary.  Diethyl 3,3′-di-tert-butyl-4,4′-dimethyl-2,2′-bipyrrole-5,5′-dicarboxylate was synthesized in four steps from ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate. The CH₂ hydrogens of the ethyl ester groups of the former are diastereotopic in the ¹H-NMR, consistent with axial chirality of the bipyrrole and restricted rotation about the 2,2′-bipyrrole bond, due to the tert-butyl groups. An X-ray structure of the crystalline target compound shows the pyrrole rings are twisted out of coplanarity by 84.5°. Corresponding author. E-mail: lightner@scs.unr.edu Received September 2, 2002; accepted September 13, 2002 Published online February 20, 2003     

Modeling liquid thermal explosion reactor containing <Emphasis Type="Italic">tert</Emphasis>-butyl peroxybenzoate

This study investigated the role played by green thermal analysis technology in promoting the use of resources, preventing pollution, reducing energy consumption and protecting the environment. The chemical tert-butyl peroxybenzoate (TBPB) has been widely employed in the petrifaction industries as an initiator of polymerization formation agent. This study established the thermokinetic parameters and thermal explosion hazard for a reactor containing TBPB via differential scanning calorimetry (DSC). To simulate thermokinetic parameters, a 5-ton barrel reactor of liquid thermal explosion model was created in this study. The approach was to develop a precise and effective procedure on thermal decomposition, runaway, and thermal hazard properties, such as activation energy (E _a), control temperature (CT), critical temperature (TCR), emergency temperature (ET), heat of decomposition (∆H _d), self-accelerating decomposition temperature (SADT), time to conversion limit (TCL), total energy release (TER), time to maximum rate under isothermal condition (TMR _iso), etc. for a reactor containing TBPB. Experimental results established the features of thermal decomposition and huge size explosion hazard of TBPB that could be executed as a reduction of energy potential and storage conditions in view of loss prevention.     

Novel solvent-controlled chemoselective palladium/copper(II) halide catalyzed oligomerization of <Emphasis Type="Italic">tert</Emphasis>-butyl acetylene

Solvent-controlled chemoselective palladium-catalyzed oligomerization of tert-butyl acetylene is reported in this paper. The reaction was carried out smoothly in benzene/n-BuOH binary solvent system. When unpolar aprotic benzene was the preponderating component in the binary system, a cyclotrimerization process occurred to produce 1,3,5-tri-tert-butylbenzene via a mechanism of three acetylene molecules, inserted step by step, forming σ-butadienyl-Pd and σ-hexatrienyl-Pd intermediates. While when the polar, protic and strong coordinating component n-BuOH, which aids Cu(II) to cleave the C-Pd σ-bonds and solvate Pd(II), Cu(II) cations, halo anion, σ-butadienyl-Pd intermediate, etc., was increased to a certain extent in the binary solvent system, the reaction proceeded readily via a n-BuOH-promoted mechanism to give (3Z,5Z)-2,2,7,7-tetramethyl-3,6-dichloro-3,5-octadiene or (3Z,5Z)-2,2,7,7-tetramethyl-3,6-dibromo-3,5-octadiene, respectively. Possible weak hydrogen bonds and n-π weak force between n-BuOH (electron pair donor (EPD)) and tert-butyl acetylene (and σ-butadienyl-Pd intermediate, electron pair acceptor (EPA)) in the latter process were also in favor of the n-BuOH promoted pathway. Meanwhile, the coupling product 2,2,7,7-tetramethyl-3,5-octadiyne was exclusively obtained when the reaction was conducted in singular polar H₂O. Influences of the solvent, catalysts, as well as possible mechanism were discussed in this paper.     

A Radiochemical Study of Reactions of Diethylsilylium Ions with Trimethyl(<Emphasis Type="Italic">tert</Emphasis>-butylamino)silane in Gas and Liquid Phases

The reaction of diethylsilylium ions with trimethyl(tert-butylamino)silane in gas and liquid phases was studied radiochemically. In contrast to the reactions of carbocations with amines, with diethylsilylium ions the proton transfer channel is not realized at all. As in the reactions of diethylsilylium ions with benzene, alcohols, and ethers, the reaction with the aminosilane is accompanied by rearrangement of the silylium ion. Formation of the condensation complex with trimethyl(tert-butylamino)silane is complicated by both its geometry and electron density distribution, despite the fact that formation of the condensation complex in this case is more exothermic than with the nucleophiles studied previously (benzene, alcohol, ether).__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 77–81.Original Russian Text Copyright © 2005 by Kochina, Vrazhnov, Sinotova, Ignat’ev.     

Stereoselective synthesis of spiro derivatives of 2,4-dimethyl-2,3,4,4a,5,6-hexahydro-6<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">c</Emphasis>]quinolizine

The reactions of 2-(3,5-dimethylpiperidino)benzaldehyde with Meldrum's acid and cyclohexane-1,3-dione occur as a tandem of the Knoevenagel condensation and cyclization promoted by the tert-amino effect. The cyclization yields only one isomer with the axial hydrogen atoms in positions 4 and 4a of the benzoquinolizine ring. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1492–1494, June, 2005.     

Structure of the oxidative dimerization product of 4,6-di(<Emphasis Type="Italic">tert</Emphasis>-butyl)pyrogallol

The structure of the oxidation product of 4,6-di(tert-butyl)pyrogallol, viz., 6,10a-dihydroxy-3,4a, 7,9-tetra(tert-butyl)-1,2,4a,10a-tetrahydrodibenzo[b,e][1,4]dioxine-1,2-dione, was established by X-ray diffraction. Dimerization of intermediate 3-hydroxy-4,6-di(tert-butyl)-1,2-benzoquinone occurs by the mechanism of Diels—Alder heterocyclization. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 267–271, February, 2007.