Polymethylations of bis(cyanomethyl)benzenes

o-, m- and p-bis(cyanomethyl)benzene were reacted with various quantities of methyllithium and methyliodide. Di and tetra methylations can be easily obtained in the cases of the meta and para isomers. Di and tri methylations were obtained in the reactions of the ortho isomer. The product from tri methylation of the ortho isomer cyclizes under the reaction conditions to a 3-indanone derivative.     

Structure-property relationships of donor/acceptor-functionalized tetrakis(phenylethynyl)benzenes and bis(dehydrobenzoannuleno)benzenes

A series of tetrakis(phenylethynyl)benzenes and bis(dehydrobenzoannuleno)benzenes have been synthesized containing tetra-substitutions of neutral, donor, and mixed donor/acceptor groups. To ascertain the importance of substitutional and structural differences of the phenylacetylenes, the optical absorption and emission properties of each series were examined. Conjugation effectiveness, electron density, planarity, and geometry of charge-transfer pathways were found to have a pronounced effect on the overall optical and material properties. Considerable self-association behavior due to face-to-face stacking in solution was observed for donor/acceptor-functionalized macrocycles and was quantified by concentration-dependent (1)H NMR measurements. A solvent-dependent polymerization of one macrocycle regioisomer was observed and characterized. To provide further insight into the energy levels and electronic transitions present, computational studies of each system were performed.     

Structure-property relationships of fluorinated donor/acceptor tetrakis(phenylethynyl)benzenes and bis(dehydrobenzoannuleno)benzenes

Nine new bisdonor/bisacceptor-functionalized tetrakis(phenylethynyl)benzene (TPEB) and six new bis(dehydrobenzoannuleno)benzene (DBA) chromophores have been synthesized. The compounds consist of electron-donating dibutylaniline groups connected through a conjugated phenyl-acetylene scaffold to benzotrifluoride, bis(trifluoromethyl)phenyl, or pentafluorophenyl acceptor groups. In comparison to previously reported analogues utilizing nitrophenyl or benzonitrile acceptor groups, the weaker acceptor groups exhibit visibly fluorescent intramolecular charge transfer (ICT) behavior, moderately narrow optical band gaps, moderately high quantum yields, and strong fluorescence solvatochromism. In this series of molecules, the strongly inductive fluoro acceptor groups result in optical properties similar to the resonance acceptor analogues, making them promising candidates for optical materials device components. The data also support recent investigations that question the utility of using UV/vis spectroscopy alone as a qualitative measure of conjugation. The bisDBAs exhibit weaker ICT behavior and self-association in solution than their corresponding nitro analogues, but show greater stability to decomposition via polymerization and smaller optical band gaps than their acyclic analogues.     

Synthesis of bis(halovinyl)benzenes by catalytic olefination

Catalytic olefination of hydrazines of terephthalic and isophthalic aldehydes with polyhaloalkanes afforded the corresponding p- and m-divinylbenzene derivatives bearing halogen atoms and various functional groups at the double bonds. Stereochemical features of the reaction were studied.     

New substituted mono-and bis(imidazolyl)pyridines and their application in nitroaldolisation reaction

New chiral nitrogen ligands based on the substituted mono-and bis(imidazolyl)pyridines have been prepared and characterised. Their complexes with cupric acetate were used as catalysts in the nitroaldolisation reaction. In the case of optically pure complexes of mono(imidazolyl)pyridine, the isolated products were 2-nitro-1-(2-nitrophenyl)ethanols or 2-nitro-1-(4-nitrophenyl)ethanols in overall yields of 49–93 % and with the maximum enantiomeric excess of 15.6 %. The complexes of bis(imidazolyl)pyridine also catalyse the nitroaldol reaction, the yields being 64–90 %, but with zero enantioselective excess. Presented at the 57th Congress of Chemical Societies, Tatranské Matliare, 4–8 September 2005.     

Selective mono-and diamination of polyfluorinated benzenes and pyridines with liquid ammonia

Amination of pentafluoropyridine, 2,3,5,6-tetrafluoropyridine, 4-chlorotetrafluoropyridine, 3,5-dichlorotrifluoropyridine, octafluorotoluene, α,α,α,2,3,5,6-heptafluorotoluene, decafluoro-m-xylene, decafluorobiphenyl, hexafluorobenzene, and pentafluorobenzene with liquid ammonia was investigated. Bis-aminodefluorination temperatures for the majority of substrates were shown to exceed significantly the corresponding temperatures of monoaminodefluorination. The optimal conditions for selective preparation of mono-and diaminopolyfluoro(het)arenes were elucidated. An efficient method for isolation of particular polyfluorophenylenediamines from product mixtures formed in nonselective reactions of pentafluorobenzene and hexafluorobenzene with aqueous ammonia based on complexation with a crown ether is proposed. Dedicated to the memory of Academician N. N. Vorozhtsov on the occasion of his 100th anniversary. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2163–2170, November, 2007.     

Synthesis and characterization of bis(glycosylamino)benzenes based on reducing disaccharides

Synthesis of bis(glycosylamino)benzenes, derived from disaccharides lactose, maltose, and cellobiose, by direct condensation and their characterization are described. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1235–1238, May, 2005.     

Biginelli reaction for synthesis of novel trifluoromethyl derivatives of bis(tetrahydropyrimidinone)benzenes

A facile one-pot three-component condensation of terephthalic aldehyde with urea and fluorinated 1,3-dicarbonyl derivatives is developed using catalytic quantities of chlorotrimethylsilane at ambient temperature. As a consequence, efficient synthesis of novel trifluoromethyl derivatives of bis(tetrahydropyrimidinone)benzenes is observed within short time periods. The procedure is shown to be equally efficient when urea is replaced with thiourea or guanidine.     

Ab initio calculation of boat benzenes in bis(2,4,6-tri-t-butylphenyl) phosphinic chloride

ab initio Calculation of the benzene skeletons of the titled compound indicated that the molecule suffers 61.4 kcal/mol higher energy than that of flat benzene rings and that the boat benzene form is even more stable than the envelope or chair form benzene.     

Studies on bis(1′-ortho-carboranyl)benzenes and bis(1′-ortho-carboranyl)biphenyls

Reactions between the C,C′-dicopper(I) derivative of ortho-carborane and ortho-, meta- and para-diiodobenzene are reported. The reaction with 1,2-C₆H₄I₂ unexpectedly afforded 2,2′-bis(1′-ortho-carboranyl)biphenyl, [HCB₁₀H₁₀CC₆H₄]₂2, whereas reactions with 1,3- or 1,4-C₆H₄I₂ provided alternative routes to 1,3-bis(1′-ortho-carboranyl)benzene 3 and 1,4-bis(1′-ortho-carboranyl)benzene 4, respectively. The crystal structure of the biphenyl derivative 2 revealed significant distortions in the biphenylene framework attributable to the proximity of the two bulky carborane cages. UV absorption spectra and electrochemical data on 2 and 3 showed little electronic communication between the two carborane cages in either, and negligible π-conjugation between the two ortho-phenylene rings in 2. However, substantial evidence was found of electronic communication between the carborane cages via the para-phenylene bridge in 4. B3LYP/6-31G^∗ computations have been carried out on compounds 2 and 4, on 4,4′-bis(ortho-carboranyl)biphenyl 6 and on 1,2-bis(1′-ortho-carboranyl)benzene 7. Those on 2, 4 and 6 show the computed geometries to be in very good agreement with the experimental geometries: those on 7 allowed the reported molecular geometry of this compound to be revised and revealed a long cage C–C bond of 1.725(3) Å.     

Anomalous photophysics of bis(hydroxystyryl)benzenes: a twist on the para/meta dichotomy

The dianions of two isomeric bis(hydroxystyryl)benzenes show dramatically different photophysical properties.     

Synthesis and structure-property relationships of donor/acceptor-functionalized bis(dehydrobenzo[18]annuleno)benzenes

Seven new bis(dehydrobenzo[18]annuleno)benzenes (bis[18]DBAs) functionalized with electron-donating dibutylamino groups and/or accepting nitro groups at various positions along the peripheries of the chromophores have been prepared. The effects of varying the donor/acceptor charge transfer pathways, chromophore lengths and molecular symmetries upon the optical band gaps are studied using UV-visible spectroscopy, and structure-property correlations are identified. It is found that bis[18]DBAs possessing donor-pi-donor and acceptor-pi-acceptor pathways exhibit the smallest band gaps, especially when an acceptor-pi-acceptor pathway is situated along the longest chromophore length in the molecule. The all-donor species is also found to exhibit efficient fluorescence with dramatic solvatochromism. The results may have value to the rational design of future NLO/TPA device components.     

Phase behavior of ionic liquids 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides with halogenated benzenes

(Liquid + liquid) miscibility temperatures as a function of composition have been determined experimentally for the binary systems formed by imidazolium based ionic liquids with bis(trifluoromethylsulfonyl)imide ([C_nMIM][NTf₂]: n = 3 to 10) with fluorobenzene, chlorobenzene, bromobenzene, iodobenzene and 1,2-dichlorobenzene. In addition, the phase diagrams for deuterated chlorobenzene, bromobenzene and 1,2-dichlorobenzene have been obtained. All the measured systems show the limited miscibility with the upper critical solution temperature behavior. Similarly to the other systems with the imidazolium cation the increase of the alkyl chain length in this cation improves the miscibility. The impact of the halogenobenzene is also very visible. The miscibility is improving in the order: iodobenzene < bromobenzene < chlorobenzene < fluorobenzene. This arrangement corresponds to the decreasing molar volume of the substituted benzenes. The disubstituted chlorobenzene is a better solvent for ionic liquids than chlorobenzene. The replacement of hydrogen for deuterium in halogenobenzenes in all cases improves the miscibility and the isotope shifts of the UCSTs are very large.     

Synthesis of bis[(3,4-ethylenedioxy)thien-2-yl]-substituted benzenes

A series of bis-EDOT-aryl monomers have been synthesized, which have blue emission characteristics with quantum yields ranging from 0.01% to 10.3%. Polymers were obtained by electrochemical synthesis. Cyclic voltammetry was employed to characterize the electrochemical behavior of these systems.     

Conformational mobility and intramolecular rearrangements of bis(3-thioxo-1-phenylpropenyl) sulfide

Possible intramolecular transformations of bis(3-thioxo-1-phenylpropenyl) sulfide were studied by the quantum-chemical semiempirical AM1 method. A group of the most stable, potentially spectroscopically discernible rotamers was distinguished. A possibility of intramolecular rearrangements giving thiirane structures was considered. The ability of bis(3-thioxo-1-phenylpropenyl) sulfide for spontaneous trimerization was evaluated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2255–2261, December, 1999.     

Thermal analysis of bis(tetraethylammonium) tetrachloroferrate(II)

Thermal decomposition of bis(tetraethylammonium) tetrachloroferrate(II) has been studied using the TG-FTIR, TG–MS and DTA techniques. The measurements were carried out in an inert atmosphere over the temperature range of 293–1073 K. The solid products of the thermal decomposition were identified by the FT-FIR, Mössbauer spectroscopy as well as the X-ray powder diffractometry. The influence of the oxidation state and the nature of a metal on thermal transformation profiles of analogous complexes have been discussed.     

Conjugated addition of bis(oxazolinyl)zinc to substituted 2-nitrovinyl benzenes: an alternative synthesis of (±)-Rolipram

In this letter we present a new 2,4,4-trimethyl-2-oxazoline anion-zinc derivative that has a remarkable thermal stability when compared with the corresponding cyanocuprate counterpart. The yields from conjugated addition to several 2-nitrovinyl benzenes are moderate to good and the reaction itself is easier to execute and cleaner. As an application, this methodology was applied to an alternative synthesis of (±)-Rolipram, a drug with several interesting biological activities.     

Conformational studies of dicyclohexylthallium chloride,bis(4-methylcyclohexyl)thallium chloride and bis(4-tert-butylcyclohexyl)thallium chloride by 1H NMR

Vicinal thallium–hydrogen coupling constants are used to discuss conformations in dicyclohexylthallium chloride, bis(4-methylcyclohexyl)thallium chloride and bis(4-tert-butylcyclohexyl)thallium chloride. Thallium does not have a very strong preference for equatorial positions in dicyclohexylthallium chloride, whereas bis(4-alkylcyclohexyl)thallium chlorides exist largely in one conformation. Bis(4-methylcyclohexyl)thallium chloride exists in three isomeric forms; the major product appears to be the cis-isomer (equatorial methyl, axial thallium), with the other two isomers probably containing thallium trans to the methyl group (axial thallium being preferred). The preference for the cis-isomer (equatorial tert-butyl, axial thallium) of bis(4-tert-butylcyclohexyl)thallium chloride is such that other isomers are not obtained.     

Conformational analysis of poly(2-hydroxyethyl methacrylate)

The poly(2-hydroxyethyl methacrylate) (PHEMA) is a disubstituted vinyl chain in which the substituents CO₂CH₂CH₂OH and CH₃ differ in size and shape. In order to verify the various characteristics of the PHEMA chain, the conformational energy calculations for meso and racemic diads, which are the segments consisting of the stereoregular isotactic and syndiotactic chains, respectively, were carried out using ECEPP/2 potential. From these calculations, the averaged geometry and the statistical weights were obtained in a local minima. The characteristic ratio, C∞ = (〈r²〉_o/nl²)∞, was determined from the statistical weights and geometries. The calculated C∞ for the isotactic and syndiotactic chain are 10.2 and 2.3, respectively. The characteristic ratio for isotactic chain is larger than that for syndiotactic chain. This shows that the syndiotactic chain is more folded than the isotactic chain is, and that the calculated tendency is in reasonably agreement with the experimental tendency of acrylate polymers.