Acid-catalyzed disproportionation of N,N-bis(4-tert-butylphenyl)hydroxylamine. Synthesis and structure of 10-[5-tert-butyl-2-(4-tert-butylphenylamino)phenyl]-3,7-di-tert-butylphenoxazine

New method of synthesis was developed for N,N-bis(4-tert-butylphenyl)hydroxylamine by reduction of the corresponding aminoxyl with hydrazine hydrate. At the treatment with strong acids this hydroxylamine derivative is converted in bis(4-tert-butylphenyl)amine and 10-[5-tert-butyl-2-(4-tert-butylphenylamino) phenyl]-3,7-di-tert-butylphenoxazine. The structure of the latter was established by X-ray diffraction analysis. The mechanism was suggested of the acid-catalyzed disproportionation of N,N-bis(4-tert-butylphenyl) hydroxylamine.     

Oxidation and reductive bromination of Bis(4-tert-butylphenyl)aminoxyl

One-electron oxidation of bis(4-tert-butylphenyl)aminoxyl with antimony pentachloride and bromine leads to the formation of oxoammonium salts with anions SbCl ₆ ^? and Br ₃ ^? respectively. The salt with the Br ₃ ^? anion converted at heating into a mixture of bromodiphenylamines which formed also from the aminoxyl as a result of previously unknown reaction of three-electron reductive bromination. The mechanisms of these reactions were assumed.     

Polymerization of ethylene with self-immobilizing bis(phenoxyimine) catalytic systems

The kinetic features of polymerization of ethylene with five methylaluminoxane-activated selfim-mobilizing bis(phenoxyimine) complexes of titanium chloride, namely, bis{2-[(4-allyloxyphenylimino)methyl]-6-tert-butylphenoxy}TiCl₂, bis{2-[(4-allyloxyphenylimino)methyl]-4,6-di-tert-butylphenoxy}TiCl₂, bis{2-[(4-allyloxyphenylimino)methyl]-6-cumylphenoxy}TiCl₂, bis{2-[(4-allyloxyphenylimino)methyl]-4,6-dicumylphenoxy}TiCl₂, and bis{2-[(4-allyloxyphenylimino)methyl]-6-1-(4-tert-butylphenyl)ethylphenoxy}TiCl₂ have been studied. The activity of these complexes in the polymerization of ethylene in the temperature range 20–80°C and an ethylene pressure of 0.3 MPa has been investigated both in the homogeneous and polymer matrix-bound states. The self-immobilizing catalytic systems possess high activity (up to 40000 kg_PE/mol_cat MPa h) and give rise to ultrahigh-molecular-weight PE (M = (2–7) × 10⁶) with an improved morphology of polymer particles.     

Reductive chlorination of bis(4-tert-butylphenyl)amine-N-oxyl nitroxyl radical

Unlike cyclic aliphatic nitroxyls, whose oxidation with halogens gives oxoammonium salts, bis(4-tert-butylphenyl)amine-N-oxyl (1) treated with chlorine undergoes reductive chlorination to the corresponding di- and trichlorodiphenylamines. Chlorine partially dealkylates the compounds obtained. Plausible mechanisms for these reactions were suggested.     

Enhancing the solubility for hypervalent ortho-sulfonyl iodine compounds

The synthesis and characterization of new hypervalent iodine reagents ArINTs (2a), ArIO (3a), and ArIO₂ (4a) (Ar=2-tert-butylsulfonyl-5-tert-butylphenyl) are described. These reagents are compared to previously reported analogous set of reagents Ar=2-tert-butylsulfonylphenyl and found to have significantly enhanced solubility and similar chemical reactivity. The X-ray crystal structures of 4a and of ArI (1a) (Ar=2-tert-butylsulfonyl-5-tert-butylphenyl) are discussed and compared. These reagents find use in atom and group transfer reactions.     

Synthesis of [μ-methyllenebis(η5-3-tert-butyl-2-methylinden-1-yl)dichlorozirconium(IV)]

An efficient synthetic approach to 3-alkyl(aryl)-2-bromoindenes was developed. The reaction of 2-bromo-3-tert-butylindene with MeMgl catalyzed by Ni(dppp)Cl₂ afforded 3-tert-butyl-2-methylindene from which bis(3-tert-butyl-2-methylinden-1-yl)methane and the correspondingansa-zirconocene were synthesized.     

Synthesis and characterization of soluble seco-porphyrazines with bulky substituents

By cyclotetramerization of 3,4-bis(4-tert-butylphenyl)pyrroline-2,5-diimine in the presence of magnesium butanolate, magnesium porphyrazinate with eight (4-tert-butylphenyl) units on the periphery has been synthesized. Its demetalation by the treatment with trifluoroacetic acid resulted in a partially oxidized product, namely, octakis(4-tert-butylphenyl)-2-seco-porphyrazine-2,3-dione. Further reaction of this product with copper(II) acetate, zinc(II) acetate, and cobalt(II) acetate led to the metallo derivatives, [octakis(4-tert-butylphenyl)-2-seco-2, 3-dioxoporphyrazinato]M(II) (M = Cu, Zn, Co). These soluble complexes have been characterized by elemental analysis, FT-IR, ¹H NMR, UV-Vis, and mass spectral data.     

Synthesis, acid-base properties, and deselenation of 5,6,8,9,11,12-hexakis(4-tert-butylphenyl)[1,2,5]selenadiazolo[3,4-b]porphyrazine

Cross cyclotetramerization of bis(4-tert-butylphenyl)fumaronitrile with 1,2,5-selenadiazole-3,4-dicarbonitrile in the presence of magnesium butoxide as template afforded a mixture of magnesium(II) porphyrazine complexes, from which magnesium complex of 5,6,8,9,11,12-hexakis(4-tert-butylphenyl)[1,2,5]selenadiazolo[3,4-b]porphyrazine was isolated by column chromatography and was subjected to demetalation on treatment with trifluoroacetic acid. The free ligand was found to undergo protonation at one meso-nitrogen atom in acid medium and deprotonation of one pyrrole ring to form monoanion by the action of bases. Reductive deselenation of the title compound with formation of vicinal diamino porphyrazine was studied by spectral and kinetic methods, and a mechanism involving two hydrosulfide ions was proposed.     

Catalytic enantioselective synthesis of atropisomeric 2-aryl-4-quinolinone derivatives with an N–C chiral axis

In the presence of an (R)-MOP-Pd₂(dba)₃ catalyst, the reaction of ortho-tert-butylaniline with 2-bromophenyl arylethynyl ketone proceeded via a tandem amination (1,4-addition of aniline to an ynone and subsequent intramolecular Buchwald–Hartwig amination) to afford axially chiral N-(2-tert-butylphenyl)-2-aryl-4-quinolinone derivatives with moderate enantioselectivity (up to 72% ee).     

Stable free radicals generated during the oxidation of 4-alkyl Hantzsch 1,4-dihydropyridines with nitrosonium — EPR evidence

Stable free radicals were observed by EPR technique during the oxidation of 4-isopropyl and 4-isobutyl Hantzsch 1,4-dihydropyridines with nitrosonium tetrafluoroborate (NO⁺BF^-4) in anhydrous and anaerobic acetonitrile at room temperature. These free radicals were assigned to diisopropyl aminoxyl and diisobutyl aminoxyl, respectively. A whole mechanism for the oxidation was suggested.     

Synthesis of aromatic tetracyclic tin compounds by template and transmetallation reactions: Alkyl vs aryl migration from tin to nitrogen

The syntheses of [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)amine]diphenyltin (1) and [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)amine]dichloro-phenyl-stannate (2) by template reactions using 3,5-di-tert-butylcatechol, aqueous ammonia and SnPh₂Cl₂ are reported. We also report the syntheses of compounds 2, [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)amine]trichloro-stannate (4), [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)methylamine]chloro-methyltin (5), and [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)-n-butylamine]n-butyl-chlorotin (6) and [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)amine]n-butyl-dichloro-stannate (7), performed by transmetallation reactions of the octahedral zinc coordination compound Zn[3,5-di-tert-butyl-1,2-quinone-(3,5-di-tert-butyl-2-hydroxy-1-phenyl)imine]₂ (3) with SnPhCl₃ or SnPh₂Cl₂, SnCl₄, SnMe₂Cl₂, Sn(nBu)₂Cl₂ and Sn(nBu)Cl₃, respectively. The X-ray diffraction structures of compounds 1, 2, 4 and 6 are reported. The transmetallation reactions with Sn(alkyl)₂Cl₂ afforded pentacoordinated tin compounds, where an alkyl group migrated from tin to nitrogen, while similar reactions with Sn-Ph compounds did not present any phenyl group migration.     

A chromatography-mass spectrometry study of aquatic chlorination of UV-filter avobenzone

We studied the reactions of 4-tert-butyl-4′-methoxydibenzoylmethane (avobenzone), the most common UV filter in formulations of sunscreens, under the conditions of disinfection. Three chlorinated compounds were identified as the main products. Their structures were confirmed by high-performance liquid chromatography-tandem mass spectrometry (HPLC–MS²) with accurate mass measurements and by gas chromatography–mass spectrometry (GC/MS). It was reliably proved, that the substitution involved the double bond of the enolic form of the diketone, rather than the activated aromatic ring, leading to the formation of 2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione and 2,2-dichloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione as the main products. The third identified product was 2-chloro-1-(4-methoxyphenyl)ethanone.     

Synthesis of biomimetic heme precursors

Three kinds of biomimetic heme precursors have been prepared. The first type is based on tetra-aminoporphyrins: either 5,10,15,20-tetrakis (o-aminophenyl)porphyrin (various atropoisomers), or 5,15-bis(2′,6′-diaminophenyl)porphyrin. The second type is based on octa-aminoporphyrins: 5,10,15,20-tetrakis (2′,6′-diamino-4′-tert-butylphenyl)porphyrin. One example of “basket handle” porphyrin demonstrates selective discrimination between O₂ and CO with an M value [M=p_1/2(O₂)/p_1/2(CO)] of 105. This is similar to values reported for various natural hemoproteins. The third type is based on aminoporphyrin templates [5, 5,10- or 5,15- and 5,10,15-(2′,6′-dinitro,4′-tert-butylphenyl)porphyrins] which have been tested in asymmetric epoxidation.     

Synthesis oftert-butyl substituted polymethine 1-benzothiopyrylium dyestuffs

A series of polymethine thiopyrylium dyestuffs of symmetrical and unsymmetrical structure, containing one to fourtert-butyl groups, has been synthesized from 6-tert-butyl-2-(p-tert-butylphenyl)-4-methyl-, 4,6-di(tert-butyl)-2-methyl-, and 6-tert-butyl-2,4-dimethyl-1-benzothiopyrylium perchlorates.     

Microwave-assisted synthesis and reverse saturable absorption of phthalocyanines and porphyrins

Soluble phthalocyanines, including tetrakis(2,9,16,23-cumylphenoxy) copper phthalocyanines (CuPc(β-CP)₄), tetrakis(1,8,15,22-cumylphenoxy) copper phthalocyanines (CuPc(α-CP)₄) as well as tetrakis(2,9,16,23-tert-butyl) copper phthalocyanines (CuPc(β-t-butyl)₄), and porphyrins (5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrins; M(TBP), M=H₂, Zn, Cu, Mg, InCl, AlCl) have been quickly synthesized by microwave irradiation. Furthermore, their reverse saturable absorption have also been investigated by dissolving them in solvent or incorporating them in polymer-silica hybrid material with a sol-gel process with polyvinyl butyral and tetraethyl orthosilicate as precursors. A new method for the preparation process of phthalocyanines and porphyrins in the solids has been successfully used.     

Optical and electronic properties of air-stable organoboron compounds with strongly electron-accepting bis(fluoromesityl)boryl groups

Three compounds with phenyl (1), 4-tert-butylphenyl (2) and 4-N,N-diphenylaminophenyl (3) groups attached to bis(fluoromesityl)boryl ((FMes)₂B) through B–C bonds have been prepared. The restricted rotation about the B–C bonds of boron-bonded aryl rings in solution has been studied by variable-temperature ¹⁹F NMR spectroscopy, and through-space F–F coupling has been observed for 3 at low temperature. Steric congestion inhibits binding of 1 by Lewis bases DABCO and tBu₃P and the activation of H₂ in their presence. Photophysical and electrochemical studies have been carried out on 2, 3, and an analogue of 3 containing a bis(mesityl)boryl ((Mes)₂B) group, namely 4. Both 2 and 3 show bright emission in nonpolar solvents and in the solid-state, very strong electron-accepting ability as measured by cyclic voltammetry, and good air-stability. In addition, 2 displayed unusually long-lived emission (τ = 2.47 s) in 2-MeTHF at 77 K. The much stronger acceptor strength of (FMes)₂B than (Mes)₂B leads to significantly red-shifted emission in solution and the solid state, stronger emission solvatochromism, and significantly lower reduction potentials. Theoretical calculations confirm that 2 and 3 tend to form highly twisted excited states with good conjugation between one FMes group and the boron atom, which correlate well with their blue-shifted solid-state emissions and low k _r values in solution.     

Inhibitory effect of 2,6-di-<Emphasis Type="Italic">tert</Emphasis>-butylphenol groups in iron and manganese porphyrins on the catalytic activity in the oxidation of hydrocarbons by hydrogen peroxide

Iron and manganese porphyrins containing 2,6-di-tert-butylphenyl groups (R₄PFeCl and R₄PMnCl) have been synthesized to be further immobilized on silica gels via various spacers. The activity of these porphyrins in the oxidation of alkanes and alkenes by hydrogen peroxide has been studied. 2,6-Di-tert-butylphenol groups decrease the catalytic activity of porphyrins in oxidation processes.     

Étude des réactions d'oxydo—réduction du neptunium dans le mélange Rbcl—CsCl (25–75% mol)

The oxidation—reduction reactions o f neptunium in molten RbCl—CsCl.Standard potentials of the systems NpO₂(VI)—NpO₂(V) and Np(IV)—Np(III) and the equilibrium constant of the following disproportionation reaction 2NP⁴⁺ + 2H₂O + 2Cl^- ? NpO⁺₂ + Np³⁺+ 4HCI have been determined in a (Rb 0,25; Cs 0,75 )C1 melt in the temperature range 660—750°C by absorption spectrophotometry. The results are com- pared with those obtained previously in (Li 0,7; K 0,3)C1, (Li, K)C1 eutectic and (Li 0,55; CsO,45)Cl.     

The first stable examples of compounds containing both diazonium and acyl azide,and synthesis of a new pyrazino[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazin-4(6H)-one heterocyclic system

The first stable compound containing both N₂⁺BF₄^? and CON₃ functional groups – 8-azidocarbonyl-3-(tert-butyl)-4-oxo-4,6-dihydropyrazolo[5,1-c][1,2,4]triazine-7-diazonium tetrafluoroborate was synthesized, and its stability and reactivity discussed. The Curtius rearrangement of 7-azido-3-(tert-butyl)-4-oxo-4,6-dihydropyrazolo[5,1-c][1,2,4]triazine-8-carbonylazide was investigated, and the synthesis of a novel heterocyclic system –pyrazino[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazin-4(6H)-one is described.     

Thiadiazoloporphyrinoids. Coordination of hexa(4-tert-butylphenyl)-substituted trithiadiazoltripyrrol macrocycle with Ni(II) in DMF

The rate constants, partial orders in the reagent concentrations and activation parameters of interaction of macroheterocyclic compound based on consecutively alternating fragments of thiazole and 3,4-bis(4-tert-butylphenyl)pyrole (3 + 3) with dehydrated Ni(OAc)₂ in dry DNF depending on the reagent concentrations and temperature were determined. Within a narrow range of the salt concentrations ((1.58?1.87) × 10^?4 mol/l), the third-order equation of the reaction rate was obtained i.e., the first order in a macrocyclic ligand and the second order in a salt, which was interpreted in terms of the mechanism of a stepwise coordination with three [Ni(OAc)]⁺ ions that is reversible only at the second step. Because of the low solubility of McH₃, the monomer-dimer equilibrium also becomes kinetically significant. The constant of McH₃ dimerization in DMF at 298 K equal to 1.6 × 10⁵ mol^?1 was determined by spectrophotometric titration.