Kinetics of the N-nitration of N-nitroso(nitroalkyl)amines

Russian Chemical Bulletin -     

New butenolides in plantlets of Virola surinamensis (Myristicaceae)

A phytochemical investigation in plantlets of the Brazilian medicinal tree Virola surinamensis resulted in the isolation and structural determination of four new compounds: 3-hydroxy-4-methyl-2-(11'-piperonyl-n-undecyl)-butenolide; 3-hydroxy-4-methyl-2-(7'-piperonyl-n-heptyl)-butanolide; 9'-(3,4-methylenedioxy-phenyl)-nonanoic acid and 13'-(3,4-methylene-dioxyphenyl)-tridecanoic acid. Thirteen compounds previously isolated from seeds and adult plants were also reported.     

Antiferromagnetic complexes involving metal---metal bonds III. Synthesis, structure and magnetic properties of heterotrinuclear complexes of the type M(CO)5L (M = Cr, Mo and w) containing [(C5H5CrSCMe3)2S] as unusual antiferromagnetic ligand L

Isostructural heterotrinuclear complexes (C₅H₅CrSCMe₃)₂S · M(CO)₅ (II–IV) were isolated from photochemical reactions between the antiferromagnetic complex (C₅H₅CrSCMe₃)₂S (I) (with the Cr---Cr bond 2.689 Å long and with the exchange parameter −2J = 430 cm⁻¹) and metal hexacarbonyls, M(CO)₆, where M is Cr, Mo, or W. According to the X-ray structural data on III and IV, complex I plays the role of an unusual antiferromagnetic ligand L bound to M through the sulphide bridge (M–S 2.58(2) Å). Its geometry remains practically unaffected by the complex formation (the Cr---Cr bond length in III and IV is 2.73(1) Å). The exchange parameter, −2J (410, 440 and 440 cm⁻¹ in II to IV, respectively), also shifts only insignificantly from that of I, which probably means that indirect exchange via the sulphide bridge in I is of minor importance compared with the direct Cr---Cr exchange. The Cr---Cr bond length may thus be correlated with the observed overall exchange coupling.     

Synthesis of esters of 3-fluoro-3-nitroacrylic acid

Conclusions The reaction of 1,3-difluoro-1,1,3,3-tetranitropropane with alkanols was used for the preparation of alkyl esters of 3-fluoro-3-nitroacrylic acid. 1,3-Difluoro-1,3,3-trinitro-1- propene and 1,3-difluoro-1,3-dinitro-2-alkoxy-1-propene were also isolated as intermediates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 709–711, March, 1989.     

Porous Structure of Aluminum–Tin Phosphate

The sorption isotherms of water and tetrachloromethane vapors are studied, and the porous structures of aluminum tin phosphate gels coprecipitated at various Al/Sn molar ratios are analyzed. The resultant samples contain both micro- and mesopores. The structure of aluminum tin phosphate is suggested to contain slitlike pores that do not change during drying because of the presence of polyaquahydroxoaluminum cations introduced via an exchange with interlayer cations of tin(IV) hydrophosphate.     

New Type of an Adsorption Layer of Organic Molecules with a Cage Structure Condensed at the Electrode/Solution Interface: The Adsorption of Cubane Derivatives on a Mercury Electrode

A synthesis and a study by method of measuring the differential capacitance on a stationary mercury drop of the adsorption of a number of cubane derivatives in a surface-inactive electrolyte are performed. It is established that the compounds studied exhibit a high surface activity. For bromine derivatives of cubane (4-bromomethoxycarbonylcubane, 4-bromohydroxymethylcubane) the formation of two-dimensional adsorption layers is discovered. Values of adsorption parameters for these compounds are evaluated with use made of the Frumkin isotherm.     

Synthesis and Catalytic Properties of Di- and Trinuclear Palladium Complexes with PCP-Pincer Ligands

Linear and branched conjugated pincer ligands having Ph₂P groups were synthesized: 3,3',5,5'- tetrakis(diphenylphosphinomethyl)diphenylacetylene, 3,3',5,5'-tetrakis(diphenylphosphinomethyl)diphenyldi- acetylene, 1,3,5-tris[3,5-bis(diphenylphosphinomethyl)phenylethynyl]benzene, and hexakis[3,5-bis(diphenylphosphinomethyl)phenylethynyl]benzene. Palladation of these ligands by heating with Pd(BF₄)₂(MeCN)₄ in boiling acetonitrile gave the corresponding di- and trinuclear ionic pincer palladium complexes. No individual complex was obtained from hexakis[3,5-bis(diphenylphosphinomethyl)phenylethynyl]benzene. The ionic com- plexes were converted into the corresponding chloride complexes by treatment with sodium chloride in a mixture of water with methylene chloride. The structure of the ionic palladium complex with 3,3',5,5'-tetrakis(diphenylphosphinomethyl)diphenylacetylene was established by X-ray analysis. The obtained palladium complexes exhibited a considerable catalytic activity in the Heck reaction of iodobenzene with ethyl acrylate and in the Michael addition of ethyl cyanoacetate with methyl vinyl ketone. The catalytic activity per palladium atom decreases as the number of palladium atoms in the complex increases.     

First organocatalyzed asymmetric Michael addition of aldehydes to vinyl sulfones

[reaction: see text] The first asymmetric direct Michael addition of aldehydes to vinyl sulfones catalyzed by N-iPr-2,2'-bipyrrolidine is described. 1,4-Adducts are obtained in good yields and enantioselectivities. The determination of absolute configuration allowed us to postulate a Si,Si transition state model, as shown previously for nitroolefins.