Mono-<Emphasis Type="Italic">meso</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylporphyrin

Summary. Treatment of meso-tetra(tert-butyl)porphyrin with sulfuric acid/n-butanol affords a mixture of porphyrin and mono-tert-butylporphyrin in relatively high yield.     

Heat capacities and thermodynamic properties of (<Emphasis Type="Italic">S</Emphasis>)-<Emphasis Type="Italic">tert</Emphasis>-butyl 1-phenylethylcarbamate

An N-tert-butyloxycarbonylated organic synthesis intermediate, (S)-tert-butyl 1-phenylethylcarbamate, was prepared and investigated by means of differential scanning calorimetry (DSC) and thermogravimetry (TG). The molar heat capacities of (S)-tert-butyl 1-phenylethylcarbamate were precisely determined by means of adiabatic calorimetry over the temperature range of 80-380 K. There was a solid–liquid phase transition exhibited during the heating process with the melting point of 359.53 K. The molar enthalpy and entropy of this transition were determined to be 29.73 kJ mol⁻¹ and 82.68 J K⁻¹ mol⁻¹ based on the experimental C _p–T curve, respectively. The thermodynamic functions, [H_T⁰ - H_298.15⁰ H_{T}^{0} - H_{298.15}^{0} ] and [S_T⁰ - S_298.15⁰ S_{T}^{0} - S_{298.15}^{0} ], were calculated from the heat capacity data in the temperature range of 80–380 K with an interval of 5 K. TG experiment showed that the pyrolysis of the compound was started at the temperature of 385 K and terminated at 510 K within one step.     

About selective methods of synthesis of 6-<Emphasis Type="Italic">tert</Emphasis>-butyl-2-methylphenol and 6-<Emphasis Type="Italic">tert</Emphasis>-butyl-2,4-dimethylphenol

Vapor phase catalytic methylation with methanol of 2-tert-butylphenol at the temperature 280–300°C proceeds selectively with formation of 6-tert-butyl-2-methylphenol. Elevating reaction temperature above 300°C leads to formation of 2,6-dimethylphenol. Reaction of 2-tert-butylphenol with methanol in alkaline medium in the presence of zinc oxide is shown to lead initially to formation of a mixture of calixarenes and methylenebisphenols that at elevated temperature exert splitting leading in future to 6-tert-butyl-2,4-dimethylphenol. Obtaining it in this reaction from 2,2′-methylenebis-(6-tert-butyl-4-methylphenol) proceeds selectively. Pathways of the reductive methylation of methylenebisphenols with methanol in alkaline medium is considered.     

Titanium tetra-<Emphasis Type="Italic">tert</Emphasis>-butoxide-<Emphasis Type="Italic">tert</Emphasis>-butyl hydroperoxide oxidizing system: Physicochemical and chemical aspects

The reaction of titanium tetra-tert-butoxide with tert-butyl hydroperoxide (1: 2) (C₆H₆, 20 C) involves the steps of formation of the titanium-containing peroxide (t-BuO)₃TiOOBu-t and peroxytrioxide (t-BuO)₃TiOOOBu-t. The latter decomposes with the release of oxygen, often in the singlet form, and also homolytically with cleavage of both peroxy bonds. The corresponding alkoxy and peroxy radicals were identified by ESR using spin traps. The title system oxidizes organic substrates under mild conditions. Depending on the substrate structure, the active oxidant species can be titanium-containing peroxide, peroxytrioxide, and oxygen generated by the system.     

DFT-calculated structure of protonated tetraphenyl <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylcalix[4]arene tetraketone

Using DFT calculations, two of the most probable structures (A, B) of the tetraphenyl p-tert-butylcalix[4]arene tetraketone·H₃O⁺ cationic complex species were derived. The hydroxonium ion H₃O⁺, placed in the coordination cavity formed by the calix[4]arene lower-rim groups, is bound by strong hydrogen bonds to the phenoxy oxygen atoms of the calix[4]arene ligand (structures A, B) and also to one carbonyl oxygen (structure B). Correspondence: Emanuel Makrlík, Faculty of Applied Sciences, University of West Bohemia, Pilsen, Czech Republic.     

Reduction and diazotization of ethyl 7-amino-3-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-oxo-4,6-dihydropyrazolo[5,1-<Emphasis Type="Italic">c</Emphasis>][1,2,4]triazine-8-carboxylate

The ester group in ethyl 7-amino-3-tert-butyl-4-oxo-4,6-dihydropyrazolo[5,1-c][1,2,4]triazine-8-carboxylate was converted for the first time to methyl by the action of lithium tetrahydridoborate in the presence of boron trifluoride–diethyl ether complex. This reaction has almost no analogies among other classes of organic compounds. New difficultly accessible 7-chloro and 7-azido derivatives were synthesized via diazotization of the reduction product, and treatment of the latter with acetic anhydride afforded the exhaustively acetylated derivative. Diazotization of ethyl 7-amino-3-tert-butyl-4-oxo-4,6-dihydropyrazolo-[5,1-c][1,2,4]triazine-8-carboxylate, followed by reaction with sodium azide, gave the corresponding azide, and the product of azo coupling with ethyl acetoacetate failed to undergo intramolecular cyclization to tricyclic pyrazolo[3,2-c: 5,1-c′]bis[1,2,4]triazine system.     

Antistress properties of sodium 1-<Emphasis Type="Italic">N</Emphasis>-acetylamino-1-carboxy-2-(3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-hydroxyphenyl)propionate

The effect of a spatially-hindered phenol, namely sodium 1-N-acetylamino-1-carboxy-2-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, on the functionality of mitochondria of rat liver was studied. Stress impact caused a 3 to 4-fold increase in the fluorescence intensity of the products of lipid peroxidation (LPO) in the membranes of these organelles. The preparation reduced the intensity of LPO to the control level, which was conductive to maintaining high functional activity of the mitochondria. Prevention of mitochondrial dysfunction was probably associated with an increase in the resistance of animals to stress factors.     

Synthesis of <Emphasis Type="Italic">tert</Emphasis>-butyl 1-(5,8-dioxohexahydro-[1,3]thiazolo[3,4-<Emphasis Type="Italic">a</Emphasis>]pyrazin-3-yl)ethylcarbamate

Two diastereomers of the previously unknown diketopiperazines tert-butyl 1-(5,8-dioxohexahydro-[1,3]thiazolo[3,4-a]pyrazin-3-yl)ethylcarbamate were synthesized and separated by column chro-matography on silica gel. During the cultivation of the crystal of one of compounds, the product was oxidized to corresponding tert-butyl 1-(5,8-dioxo-5,6,7,8-tetrahydro[1,3]thiazolo[3,4-a]pyrazin-3-yl)-ethylcarbamate. The X-ray crystal structure of the latter was established.     

Synthesis of acridinyl- and fluorenylidenehydrazido derivatives of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butylcalix[4]arene

p-tert-Butylcalix[4]arenes substituted at the lower rim by acetic acid hydrazide residues reacted with methoxy(ethoxy)acridine and fluoren-9-one derivatives to give a series of calixarenes containing N′-fluorenylidene- and N′-acridinylacetohydrazide residues. It was found that modification of the hydrazide moiety does not affect the conformation of the initial macroring and that it can lead in some cases to unsymmetrically substituted calixarenes.     

Electroluminescence and photovoltaic properties of bis{<Emphasis Type="Italic">N</Emphasis>-[2-(benzothiazol-2-yl)phenyl]-<Emphasis Type="Italic">N</Emphasis>-(4-methylphenylsulfonyl)amido}zinc

A dual function (electroluminescence and photosensitivity) of devices based on bis{N-[2-(benzothiazol-2-yl)phenyl]-N-(4-methylphenylsulfonyl)amido}zinc was studied. It was shown that both luminescent and photovoltaic properties are strongly dependent on exсiplex formation.     

New synthetic approach to aminoethoxy derivatives of <Emphasis Type="Italic">p</Emphasis>-(<Emphasis Type="Italic">tert</Emphasis>-butyl)calix[4]arene

A new procedure has been proposed for the synthesis of mono- and bis(2-aminoethoxy)-p-(tertbutyl) calix[4]arenes from the corresponding mono- and bis[2-(1,3-dioxoisoindol-2-yl)ethoxy]-p-(tert-butyl)-calix[4]arenes.     

Synthesis of Mono- and Tetraalkylamide Derivatives of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butylthiacalix[4]arene

Mono- and tetrasubstituted derivatives of p-tert-butylthiacalix[4]arene containing acrylate and acrylamide fragments are synthesized for the first time. The Michael aza-addition of benzylamine to the synthesized acrylamide and acrylate thiacalixarene derivatives is studied.     

Synthesis of (<Emphasis Type="Italic">E</Emphasis>)-<Emphasis Type="Italic">N</Emphasis>-(3-alkoxy-4-acyloxyphenylmethylene)-<Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">e</Emphasis>-cyclohexyl)amines

Previously unknown E isomers of azomethines (Schiff bases) were synthesized from vanillal and vanillin esters by their reaction with cyclohexylamine.     

Reaction of Thiocarboxylic Acids with <Emphasis Type="Italic">N</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butyl-2-halo-2-methylpropanimines

Reaction of N-tert-butyl-2-chloro-2-methylpropanimine with thiocarboxylic acids has proceeded by two routes, one involving nucleophilic substitution of the chlorine atom in the primary iminium salt by acylthio group, and another via reduction of its cation at the C–Cl bond. Thiocarboxylic acids have reacted with 2-bromoaldimines only via reduction of primary salt cation at the C–Br bond. Acylthio-substituted iminium salts, aldehydes, and their acetals have been prepared.     

Micelle formation of polystyrene-<Emphasis Type="Italic">block</Emphasis>-poly(4-<Emphasis Type="Italic">tert</Emphasis>-butoxystyrene) in hexane

A new type of hexane-soluble polymeric surfactant based on poly(4-tert-butoxystyrene) (P ^t BSt) was prepared by the nitroxide-mediated living radical polymerization, and their self-assemblies in hexane were explored. Polystyrene-block-P ^t BSt diblock copolymers with six different P ^t BSt block lengths were obtained by the sequential living radical polymerization of styrene followed by 4-tert-butoxystyrene using 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator; Mn(P ^t BSt block) = 13,500, 21,700, 26,600, 47,500, 91,300, and 108,000 at the constant length of the PSt block (Mn = 12,900). Dynamic light-scattering studies demonstrated that the copolymers self-assembled into monodispersed spherical micelles in hexane. The hydrodynamic diameter of the micelles increased with an increase in the P ^t BSt block length. The micellar size also increased as the copolymer concentration increased. However, the size decreased as a result of the increasing temperature due to a decrease in the aggregation number. The ¹H NMR analysis confirmed that the copolymers formed micelles with PSt cores.     

Conformations and properties of <Emphasis Type="Italic">O</Emphasis>-Alkyl-<Emphasis Type="Italic">S</Emphasis>-(2-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dialkylamino)-ethylmethylthiophosphonates

Conformers of the biologically active compounds CH₃P(O)(OR)(SCH₂CH₂NR ₂ ^′ ), where (I) R = i-C₄H₉, R′ = C₂H₅ and (II) R = C₂H₅, R′ = i-C₃H₇, are calculated within the AM1 level of theory. The elongated and twisted forms with maximum and minimum distances between a nitrogen atom and those of a phosphorus tetrahedron, respectively, and bearing a syn and anti oriented alkoxy group relative to a phosphoryl oxygen, are studied. It is found that the differences between the energy, electronic, and geometric parameters of these forms are apparent in differences between their properties, e.g., the ability to participate in complexation and protonation, reactions that to some extent simulate the interaction between a substance and a biological object.     

Modification of silica nanoparticles with stereisomers of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylthiacalix[4]arene containing four 2-oxo-2-{[3-(triethoxysilyl)prop-1-yl]amino}ethoxy substituents at the lower rim

Three stereoisomers (cone, partial cone, and 1,3-alternate) of p-tert-butylthiacalix[4]arene bearing four anchor propyltriethoxysilane substituents at the lower rim were synthesized for the first time. Surface modification of silica nanoparticles (d = 12 nm) with the synthesized macrocycles gave novel hybride thiacalix [4]arene?SiO₂ particles. The obtained nanostructured adsorbents were found to efficiently extract nitroaromatic compounds from aqueous solutions. The partial cone and 1,3-alternate thiacalix[4]arene–SiO₂ hybrid particles showed affinity to nitrophenols.     

Chemoselective acylation of monosubstituted thiacalix[4]arene with di-<Emphasis Type="Italic">tert</Emphasis>-butyl dicarbonate

Mono-, di-, and tetrasubstituted derivatives of p-tert-butylthiacalix[4]arene containing tert-butylcarbamate, tert-butylcarbonate, and tert-butyl fragments have been prepared for the first time. Depending on the reaction conditions (reagents ratio, temperature, and the presence of a base), the interaction of the monoamine derivative of p-tert-butylthiacalix[4]arene with di-tert-butyl dicarbonate can lead to the formation of mono-, di-, and tetrasubstituted products.     

Halocyclization of 3-{[2-methyl(bromo)prop-2-en-1-yl]-sulfanyl}-5<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazino[5,6-<Emphasis Type="Italic">b</Emphasis>]indoles

Reactions of 3-[(2-bromoprop-2-en-1-yl)sulfanyl]-5H-[1,2,4]triazino[5,6-b]indole with bromine and of 3-[(2-methylprop-2-en-1-yl)sulfanyl]-5H-[1,2,4]triazino[5,6-b]indole with iodine and bromine afforded 3-halomethyl-10H-[1,3]thiazolo[3′,2′: 2,3][1,2,4]triazino[5,6-b]indol-4-ium halides whose structures were determined by ¹H NMR and X-ray analysis.     

Synthesis of new <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylcalix[4]arene derivatives containing photopolymerizable 1,3-butadiyne fragments

Successive functionalization of p-tert-butylcalix[4]arene afforded a bifunctional derivative containing photopolymerizable pentacosa-10,12-diynoic acid fragments on the upper rim and propargyl groups on the lower rim of the macrocycle having a cone structure. The functionalization can be readily accomplished via copper-catalyzed azide–alkyne cycloaddition under mild conditions.