Synthesis of Thiochroman 1,1-Dioxide Derivatives on the Basis of 2,4,6-Trinitrotoluene

Treatment of 2,4,6-trinitrotoluene with -mercaptocarboxylic acid esters and subsequent oxidation gave 2-(alkoxycarbonyl-R-methylsulfonyl)-4-X-6-nitrotoluenes which were brought into Knoevenagel condensation with aromatic aldehydes (heating in benzene in the presence of secondary amine acetates). As a result of intramolecular cyclization, 2-alkoxycarbonyl-3-aryl-2-R-5-X-7-nitrothiochroman 1,1-dioxides (R = H, Me; X = NO₂, R'SO₂) were obtained. The developed procedure opens the way to hitherto unknown thiochroman 1,1-dioxide derivatives.     

A Theoretical Study of Complex Formation between Formaldehyde and Lithium

Ab initio SCF and CI calculations on the cationic and neutral complexes of formaldehyde and lithium are reported. For the cationic complex CH₂O/Li⁺, the stabilization energy of 41.7 kcal/mol obtained from the SCF calculation increases to 51.6 kcal/mol if a configuration interaction is introduced. For the neutral complex CH₂O^?/Li⁺, the C_2v-conformer of the ²A₁-state with the equilibrium bond distances of d(C? O) = 1.23 Å and d (O? Li) = 1.90 Å is calculated to be more stable than the ₂B₁-state with d (C? O) = 1.34 Å, and d (O? Li) = 1.65 Å. Charge transfer and polarization effects upon complex formation are discussed.     

UHF-CI studies of energy barriers for the abstraction and exchange reactions in the system H + CH4

UHF and CI calculations, using the direct CI method, and double-zeta plus polarization functions basis sets, have been performed on the more important parts of the energy hypersurface for CH₅. The abstraction H + CH₄ → H₂ + CH₃ and the inversion substitution reaction H′ + CH₄ → CH₃H′ + H have been studied in detail. The predicted barriers for these two reactions are 13.5 and 36.6 kcal/mol, respectively. The abstraction reaction is, in agreement with experiment, found to be almost thermo-neutral with a heat of reaction of 1.5 kcal/mol.     

13C NMR Spectra of polycyclic compounds: stereochemistry of spiro(bicyclo[2.2.1]hepta-2,5-diene-7,1′-cyclopropane) dimers

The structures of the dimerization products of spiro(bicyclo[2.2.1]hepta-2,5-diene-7,1-cyclopropane) have been solved using¹³C NMR spectroscopy and their stereochemical assignments made. The methylene carbon atom signals for the spirocyclopropane fragment can be used as diagnostic signals in making the stereochemical assignments.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 559–564, March, 1990.     

Some approaches to the synthesis of fluorinated alcohols and esters. I. Completely fluorinated esters from the hunsdiecker reaction of silver F-alkanoates with iodine

A completely fluorinated ester of the type R_FCO₂CF₂R_F′ was obtained from reaction of silver 3,6,9-trioxa-F-undecanoate and iodine with a diluent at 130°. This new substance resembled closely the previously prepared 1,1-dichloro-F-alkyl esters and was hydrolytically and thermally labile. Substitution products, R_FCOY (Y = nucleophile) and pyrolysis products, R_FCOF and R_F′COF were isolated and characterized. It appears probable that the acyl hypoiodite and the iodo-F-alkane reacted by an S_Ei-type process to give the completely fluorinated ester.     

Swallowtail porphyrins: synthesis, characterization and incorporation into porphyrin dyads

The incorporation of symmetrically branched tridecyl ("swallowtail") substituents at the meso positions of porphyrins results in highly soluble building blocks. Synthetic routes have been investigated to obtain porphyrin building blocks bearing 1-4 swallowtail groups. Porphyrin dyads have been synthesized in which the zinc or free base (Fb) porphyrins are joined by a 4,4'-diphenylethyne linker and bear swallowtail (or n-pentyl) groups at the nonlinking meso positions. The swallowtail-substituted Zn(2)- and ZnFb-dyads are readily soluble in common organic solvents. Static absorption and fluorescence spectra and electrochemical data show that the presence of the swallowtail groups slightly raises the energy level of the filled a(2u)(pi) HOMO. EPR studies of the pi-cation radicals of the swallowtail porphyrins indicate that the torsional angle between the proton on the alkyl carbon and p-orbital on the meso carbon of the porphyrin is different from that of a porphyrin bearing linear pentyl groups. Regardless, the swallowtail substituents do not significantly affect the photophysical properties of the porphyrins or the electronic interactions between the porphyrins in the dyads. In particular, time-resolved spectroscopic studies indicate that facile excited-state energy transfer occurs in the ZnFb dyad, and EPR studies of the monocation radical of the Zn(2)-dyad show that interporphyrin ground-state hole transfer is rapid.     

Synthesis of 11-N-arylaminomethylene derivatives of 8-azasteroies. A new rection of cyclic Schiff's bases

Institute of Bioorganic Chemistry, Belarus' Academy of Science, Minsk, 220141. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 266–267, February, 1995. Original article submitted December 15, 1994.     

Test method for the separate determination of mercury(II), cadmium, and lead in one sample on the fibrous sorbent PANV-AV-17

The sorption of Hg(II), Cd(II), and Pb(II) as anionic complexes on the solid phase of polyacrylonitrile fiber filled with the AV-17 anion exchanger from NaCl and KI solutions and their complexation with 4-(2-pyridylazo)resorcinol (PAR) and dithizone were studied. A test method was developed for the individual determination of Hg(II), Cd(II), and Pb(II) from one sample on three support disks. From the same solution, by the successive sorption on two disks from a 0.2 M NaCl solution, mercury was determined with dithizone and cadmium was determined with PAR. After the addition of a KI solution and sorption on the third disk, lead was determined with PAR. Using the added-found method, the procedure was approved in the analysis of natural sodium chloride water. The detection limit was 0.01 mg/L for Hg(II) and 0.02 mg/L for Cd(II) and Pb(II) for a volume of the analyzed sample of 25 mL. The time of the analysis of five or six samples (determination of three elements) is no longer than 50 min.     

Über die Alkaloide der Granatapfelbaumrinde. IV

Zusammenfassung Die früheren Befunde über den Gehalt an Isopelletierin in der Granatapfelbaumrinde wurden an 5 weiteren Rindenproben bestätigt. Isopelletierin wurde zu 30 bis 40% in den Gesamtalkaloiden aufgefunden.Versuche zeigen, daß das opt.-akt. Methylisopelletierin in schwach alkalischer Lösung bei 20° wohl racemisiert, aber nicht zersetzt wird.I.:F. Galinovsky undO. Vogl, Mh. Chem.83, 1055 (1952). b) II.:F. Galinovsky, G. Bianchetti undO. Vogl, Mh. Chem.84, 1221 (1953). c) III.:F. Galinovsky undF. Höllinger, Mh. Chem.85, 1012 (1954).