- Liquid crystalline behaviour of polymer networks based on segmented chain mesogenic polymers
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The synthesis of some crosslinked polymers based on a segmented-chain polymeric mesogen containing variable amounts of a side chain substituent is reported. The unswollen networks show thermotropic mesomorphism of nematic character whose stability decreases with increasing substitution and crosslink density. Depending on the same parameters, the swollen networks may show optical anisotropy at room temperature whose origin is attributed to phase separation.
- Aurino,Caruso,Pragliola,Roviello,Sirigu
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Read Online
- Investigation of hydro-lipophilic properties of n-alkoxyphenylhydroxynaphthalenecarboxamides ?
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The evaluation of the lipophilic characteristics of biologically active agents is indispensable for the rational design of ADMET-tailored structure–activity models. N-Alkoxy-3-hydroxynaphthalene-2-carboxanilides, N-alkoxy-1-hydroxynaphthalene-2-carboxanilides, and N-alkoxy-2-hydroxynaphthalene-1-carboxanilides were recently reported as a series of compounds with antimycobacterial, antibacterial, and herbicidal activity. As it was found that the lipophilicity of these biologically active agents determines their activity, the hydro-lipophilic properties of all three series were investigated in this study. All 57 anilides were analyzed using the reversed-phase high-performance liquid chromatography method for the measurement of lipophilicity. The procedure was performed under isocratic conditions with methanol as an organic modifier in the mobile phase using an end-capped non-polar C18 stationary reversed-phase column. In the present study, a range of software lipophilicity predictors for the estimation of clogP values of a set of N-alkoxyphenylhydroxynaphthalenecarboxamides was employed and subsequently cross-compared with experimental parameters. Thus, the empirical values of lipophilicity (logk) and the distributive parameters (π) were compared with the corresponding in silico characteristics that were calculated using alternative methods for deducing the lipophilic features. To scrutinize (dis)similarities between the derivatives, a PCA procedure was applied to visualize the major differences in the performance of molecules with respect to their lipophilic profile, molecular weight, and violations of Lipinski’s Rule of Five.
- Kapustikova, Iva,Bak, Andrzej,Gonec, Tomas,Kos, Jiri,Kozik, Violetta,Jampilek, Josef
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- Inclusion complexes of a new family of non-ionic amphiphilic dendrocalix[4]arene and poorly water-soluble drugs naproxen and ibuprofen
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The inclusion complexes of a new family of nonionic amphiphilic calix[4]arenes with the anti-inflammatory hydrophobic drugs naproxen (NAP) and ibuprofen (IBP) were investigated. The effects of the alkyl chain's length and the inner core of calix[4]arenes on the interaction of the two drugs with the calix[4]arenes were explored. The inclusion complexes of Amphiphiles 1a-c with NAP and IBP increased the solubility of these drugs in aqueous media. The interaction of 1a-c with the drugs in aqueous media was investigated through fluorescence, molecular modeling, and 1H-NMR analysis. TEM studies further supported the formation of inclusion complexes. The length of lipophilic alkyl chains and the intrinsic cyclic nature of cailx[4]arene derivatives 1a-c were found to have a significant impact on the solubility of NAP and IBP in pure water.
- Khan, Khalid,Lal Badshah, Syed,Ahmad, Nasir,Rashid, Haroon Ur,Mabkhot, Yahia
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- Synthesis and mesomorphic properties of 2,4-bis(4′-n-pentyloxybenzoyloxy)- benzylidine-4″- n-alkoxyaniline
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The synthesis and mesomorphic properties of a new series of 2,4-bis(4′-npentyloxybenzoyloxy)- benzylidine-4″ -n-alkoxyaniline (DC5An) are reported. The molecular structure of compounds was confirmed by FTIR, 1H-NMR, 13C-NMR, mass spectroscopy and elemental analysis. The mesomorphic properties were studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) measurements. All compounds of the series exhibit nematic (N) and smectic C (SmC) phases. The first four homologues (DC5A1-DC5A4) display a N mesophase, whereas the highest homologues (DC5A5-DC5A10) exhibit an enantiotropic dimorphism N and SmC phases. The mesomorphic properties of the present series are compared and discussed with other structurally related series.
- Hamad, Wali M.,Azeez, Hashim J.,Al-Dujaili, Ammar H.
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- Properties of liquid crystals and Cu2+ recognition based on Schiff bases
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Two series of new Schiff base compounds were synthesized. For Schiff base compounds with a pyridine nitrogen atom in 4-position (7a-e), their supramolecular hydrogen bonding complexes show good liquid crystal properties. However, no liquid crystal property is observed for 8a-e. Results of theoretical calculations demonstrate that it is the intermolecular hydrogen bond of Schiff base compounds (8a-e) that prevents the formation of supramolecular hydrogen bonding. The Schiff base compounds, with terminal alkoxy chains, can recognize Cu2+ selectively with a color change. Nevertheless, others cannot recognize Cu2+.
- Liu, Zhilian,Yu, Zhenning,Zhang, Jian,Zhang, Shuxiang
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- Enhanced Reactivity of Aerobic Diimide Olefin Hydrogenation with Arylboronic Compounds: An Efficient One-Pot Reduction/Oxidation Protocol
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A catalyst-free and efficient method for simultaneous olefin hydrogenation and oxidation of arylboronate esters to phenols with hydrazine hydrate and molecular oxygen is presented. The process is based on the utilization of a readily available Lewis acidic arylboron compound, which evades common problems associated with the catalyst-free aerobic hydrogenation of olefins with diimide. Using an operationally simple procedure, the protocol smoothly delivers phenol derivatives and various alkanes in excellent yields with remarkable functional group compatibility. The method allows the reaction to be scaled up to 1 g of the starting materials.
- Santra, Surojit,Guin, Joyram
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supporting information
p. 7253 - 7257
(2015/11/25)
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- Synthesis and Biological Evaluation of N-Alkoxyphenyl-3-hydroxynaphthalene-2-carboxanilides
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A series of fifteen new N-alkoxyphenylanilides of 3-hydroxynaphthalene-2-carboxylic acid was prepared and characterized. Primary in vitro screening of the synthesized compounds was performed against Staphylococcus aureus, three methicillin-resistant S. aureus strains, Mycobacterium tuberculosis H37Ra and M. avium subsp. paratuberculosis. Some of the tested compounds showed antibacterial and antimycobacterial activity against the tested strains comparable with or higher than that of the standards ampicillin or rifampicin. 3-Hydroxy-N-(2-propoxyphenyl)naphthalene-2-carboxamide and N-[2-(but-2-yloxy)-phenyl]-3-hydroxynaphthalene-2-carboxamide had MIC = 12 μM against all methicillin-resistant S. aureus strains; thus their activity is 4-fold higher than that of ampicillin. The second mentioned compound as well as 3-hydroxy-N-[3-(prop-2-yloxy)phenyl]-naphthalene-2-carboxamide had MICs = 23 μM and 24 μM against M. tuberculosis respectively. N-[2-(But-2-yloxy)phenyl]-3-hydroxynaphthalene-2-carboxamide demonstrated higher activity against M. avium subsp. paratuberculosis than rifampicin. Screening of the cytotoxicity of the most effective antimycobacterial compounds was performed using THP-1 cells, and no significant lethal effect was observed for the most potent compounds. The compounds were additionally tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. N-(3-Ethoxyphenyl)-3-hydroxynaphthalene-2-carboxamide (IC50 = 4.5 μM) was the most active PET inhibitor. The structure-activity relationships are discussed.
- Gonec, Tomas,Zadrazilova, Iveta,Nevin, Eoghan,Kauerova, Tereza,Pesko, Matus,Kos, Jiri,Oravec, Michal,Kollar, Peter,Coffey, Aidan,O'Mahony, Jim,Cizek, Alois,Kralova, Katarina,Jampilek, Josef
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p. 9767 - 9787
(2015/08/06)
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- Dual thermo- and light-responsive nanorods from self-assembly of the 4-propoxyazobenzene-terminated poly(N-isopropylacrylamide) in aqueous solution
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Abstract Both temperature and light stimuli-responsive 4-propoxyazobenzene-terminated poly(N-isopropylacrylamide)s (PNIPAMs) were successfully synthesized by the atom transfer radical polymerization (ATRP) of NIPAM. 1H NMR and UV-vis absorption spectra indicated rapid photoisomerization rate of 4-propoxyazobenzene moiety. Interestingly, the lower critical solution temperature (LCST) for PNIPAM aqueous solution clearly decreased after UV irradiation, and the repeated LCST difference (ΔTmaxy = 5°C) depended on both the number-average molecular weight and amount of azobenzene chromophore. Dynamic light scattering (DLS) and static light scattering (SLS) measurements showed that the PNIPAM aqueous solution could self-assemble into nano-micelles with 4-propoxyazobenzene as the hydrophobic cores and PNIPAM chains as the hydrophilic shells. UV irradiation induced the increase of particle size due to the formation of much looser cores of cis-azobenzene. TEM images showed the presence of both nanorods and spherical micelles. After UV irradiation, the unstable spherical micelles transformed to metastable nanorods, then to longer rods, and finally the longer rods began to transform to flake-like particles via horizontal inter-rod aggregation above LCST.
- Xue, Xiaoqiang,Yang, Jing,Huang, Wenyan,Yang, Hongjun,Jiang, Bibiao,Li, Fang,Jiang, Yun
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p. 195 - 204
(2015/08/18)
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- Magnetically recoverable catalytic Co-Co2B nanocomposites for the chemoselective reduction of aromatic nitro compounds
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Magnetically recoverable and recyclable Co-Co2B nanocomposites are described for the catalytic and chemoselective reduction of nitroarenes using two different hydrogen sources, sodium borohydride and hydrazine hydrate. Both the systems display an interesting chemoselective reduction switch. The kinetics of reduction of nitroaromatics were studied for the first time and follow nitroreductase enzyme-like kinetics with exceedingly high Kcat (5.2 × 104 s-1) and Kcat/KM (4.4 × 106 M-1 s-1) values, reaching the state of catalytic perfection. The recyclability of the catalyst system was studied by magnetically recovering the nano composite catalyst.
- Vernekar, Amit A.,Patil, Sagar,Bhat, Chinmay,Tilve, Santosh G.
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p. 13243 - 13250
(2013/09/02)
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- Liquid-crystalline polymorphism of 4-heptyloxybenzylidene-4′- alkyloxyanilines and their phase equilibrium with 4-octyloxyphenyl 4-nitrobenzoate
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This paper describes the synthesis and liquid-crystalline properties of the homologous series of 4-heptyloxybenzylidene-4′-alkyloxyanilines (7-n). Six of them are presented for the first time. Based on the polarization microscopy (POM and TOA methods) and the calorimetric (DSC) measurements following polymorphism has been detected: nematic, smectic C and smectic I mesophases. The presence of these mesophases was confirmed by the miscibility method, using 4-octyloxyphenyl 4-nitrobenzoate and terephtal-bis (4-butyloaniline) as a mesophase references. Extraordinary results have been found in the mixtures of the investigated compounds with 4-octyloxyphenyl 4-nitrobenzoate; Induced smectic A has been observed, which is connected with very strong intermolecular interactions. Additionally destabilization of nematic and smectic C phases was visible.
- Godzwon, Joanna,Sienkowska, Monika J.,Galewski, Zbigniew
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- The synthesis and NLO properties of 1,8-naphthalimide derivatives for both femtosecond and nanosecond laser pulses
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Four 1,8-naphthalimide derivatives were synthesized for new nonlinear optical(NLO) materials. Hydrazone group as a p-π structure was introduced into the molecule to extend conjugation and produce NLO properties. Their linear and nonlinear optical (NLO) properties were studied in details. The results show that these compounds possess strong excited-state absorption (ESA) properties and optical limiting with nanosecond laser pulses at 532 nm. Moreover, they also preserve the luminescence originated from naphthalimide and two-photon absorption (TPA) behaviour which can be observed under femtosecond laser pulses ranged from 750 to 870 nm. The broad-band optcial limiting properties of these compounds indicate that they can be potentially applicated in optical limiting materials.
- Ye, Gao-Jie,Zhao, Ting-Ting,Jin, Zheng-Neng,Gu, Pei-Yang,Mao, Jia-Yuan,Xu, Qing-Hua,Xu, Qing-Feng,Lu, Jian-Mei,Li, Na-Jun,Song, Yin-Ling
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p. 271 - 277
(2012/05/04)
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- Calix[4]arene with lower-rim β-amino α,β-unsaturated ketones containing bis-chelating sites as a highly selective fluorescence turn-on chemosensor for two copper(II) ions
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We report herein the synthesis of a fluorescence turn-on chemosensor, 25,27-bis{N-[1-(4-{[4-amino-4-(1-naphthyl)-2-oxo-3-butenyl]oxy}phenyl) aminocarbonyl]methoxy}-26,28-dihydroxycalix[4]arene (3b), which is highly selective toward Cu2+. The fluorescence intensity of 3b was enhanced upon adding [Cu(ClO4)2], which reached a maximum with approximately 4 equiv. of Cu2+ but then started to decrease in intensity at higher Cu2+ concentrations. Job plot experiments revealed a 1:2 binding stoichiometry of 3b with Cu2+. Based on 1H NMR titration results, we infer that there are two possible binding sites for Cu2+ in 3b: one at the lower-rim phenolic-OH and amide groups, and the second at the β-amino α,β-unsaturated ketone groups. It is important to note that during the complexation of 3b with [Cu(ClO4)2], the Cu2+ ions were reduced to Cu+ by both the phenolic OH and the amines of the β-amino α,β-unsaturated ketones. Furthermore, control compounds 6 and 9b were synthesized to clarify the possible binding sites of Cu2+ in 3b. By comparing the binding constants of 3b, 6, and 9b with Cu2+, we found that 3b exhibited a positive allosteric behavior toward the coordination of two Cu2+ ions. Calix[4]arene 3b shows high binding selectivity toward Cu2+ ions, which causes a dramatic enhancement of the fluorescence intensities at 341 and 452 nm by 4- and 40-fold, respectively. Chemosensor 3b can recognized two Cu2+ ions; both ions are reduced to Cu+ by both the phenolic-OH and the amines of the β-amino α,β- unsaturated ketones. Copyright
- Ho, I-Ting,Chu, Jean-Ho,Chung, Wen-Sheng
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p. 1472 - 1481
(2011/04/17)
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- Studies of calamitic liquid crystalline compounds involving ester-azo central linkages with a biphenyl moiety
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Two mesogenic homologous series involving ester-azo central linkages with a biphenyl moiety have been synthesized, such as 4'-[(4-n-alkoxyphenyl)diazenyl] biphenyl-4-ol (series I) and 4'-[(4-n-alkoxyphenyl) diazenyl]-4-butoxy phenyl biphenyl-4-carboxylate (series II). Azobiphenyl of series I having a free hydroxyl group with strong hydrogen bonding exhibits a high-temperature enantiotropic smectic phase. Whereas in series II, compounds containing C 1-C8 carbon atoms exhibit only a monotropic smectic phase and compounds with C10, C12, C14, and C 16 atoms show an enantiotropic smectic phase. These compounds were characterized by elemental analysis, FT-IR, 1H-NMR, and mass spectral studies. The phase transition and mesogenicity of these substances were studied by polarizing optical microscopic and differential scanning calorimetric techniques. Their thermal stabilities and other characteristics are discussed. Copyright Taylor &Francis Group, LLC.
- Thaker,Dhimmar,Patel,Solanki,Patel,Chothani,Kanojiya
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experimental part
p. 172 - 191
(2012/07/27)
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- Role of terminal heterocyclic ring on mesomorphic properties of homologous series
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Two new homologous series of compounds with a heterocyclic ring having sulfur and oxygen as a hetero atom derived from p-hydroxy acetophenone and alkoxy aniline containing cinnamate-azomethine as central linkages have been synthesized. viz. 4(furalacryloxy) α-methyl benzylidine-4′-alkoxy aniline and 4(thianylacryloxy) α-methyl benzylidine-4′-alkoxy aniline. The compound of both the series have been characterized by elemental analysis, FT-IR, 1H-NMR, and mass spectrometry method. Their liquid crystalline properties have been investigated by optical polarizing microscopy and differential scanning calorimetry (DSC) studies. All the derivatives are mesomorphic in nature showing the nemetic phase. The mesomorphic properties of the present two series are compared with other structurally related series to evaluate the effect of thiophene and furan on mesomorphism. Copyright Taylor & Francis Group, LLC.
- Thaker,Patel,Solanki,Dhimmer,Dave
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experimental part
p. 63 - 80
(2010/09/05)
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- Highly chemoselective reduction of aromatic nitro compounds by copper nanoparticles/ammonium formate
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(Chemical Equation Presented) A highly chemoselective reduction of aromatic nitro compounds to the corresponding amino derivatives has been achieved by a combination of copper nanoparticles and ammonium formate in ethylene glycol at 120°C. The reductions are successfully carried out in presence of a wide variety of other reducible functional groups in the molecule, such as Cl, I, OCH2Ph, NHCH2Ph, COR, COOR, CN, etc. The reactions are very clean and high yielding.
- Saha, Amit,Ranu, Brindaban
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p. 6867 - 6870
(2008/12/22)
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- Inherently chiral calix[4]arene-based bifunctional organocatalysts for enantioselective aldol reactions
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Two optical pure m-dimethylamino substituted inherently chiral calix[4]arene derivatives 8a and 8b bearing an l-prolinamido group have been synthesized by two routes, and structurally studied by the usual spectroscopic methods and X-ray crystallographic analysis. It was found that both of 8a and 8b could be utilized as bifunctional organocatalysts to efficiently promote the aldol reactions between aromatic aldehydes and ketones in the presence of acetic acid. Especially, with 8a as the catalyst, the reaction between 4-nitrobenzaldehyde and cyclopentanone at -20 °C gave the anti-aldol product up to 94% ee, while the anti-aldol product in up to 94:6 dr and 79% ee was obtained when 4-cyanobenzaldehyde was used as the aldol donor. Moreover, it was also demonstrated that the inherently chiral calixarene skeleton with (cS)-conformation in 8a was identified as the matched configuration of the stereogenic elements, and the inherently chiral moiety might play an important role in helping to stereocontrol the reaction.
- Xu, Zhen-Xiang,Li, Guang-Ke,Chen, Chuan-Feng,Huang, Zhi-Tang
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p. 8668 - 8675
(2008/12/21)
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- Palladium nanoparticles-catalyzed chemoselective hydrogenations, a recyclable system in water
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Chemoselective hydrogenation of double bonds in the presence of various functional groups occurred in high yields using water or toluene as solvent, and Pd nanoparticles as catalyst. Up to nine recyclings were achieved in water without decrease of the catalyst activity.
- Callis, Nuria Miro,Thiery, Emilie,Le Bras, Jean,Muzart, Jacques
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p. 8128 - 8131
(2008/03/13)
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- Smectic polymorphism of 4-nonyloxybenzylidene-4′-alkyloxyanilines
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This paper describes liquid-crystalline polymorphism of the homologous series of 4-nonyloxybenzylidene-4′-alkyloxyanilines. Based on the polarization microscopy (POM, TOA) and the calorimetric (DSC) measurements the following mesophases were detected: nematic, smectic A, smectic C, smectic B, smectic I and smectic G. The presence of these mesophases was confirmed by the miscibility method, using: 4-heptyloxybenzilidene-4′-pentylaniline, 4-hexyl-4′-decyloxyazobenzene and 4-nonyloxybenzilidene-4′-butylaniline as mesophase references. Influence of the alkyl chain length on the type of mesophases and entropic effects of phase transition are discussed.
- Godzwon, Joanna,Sienkowska, Monika J.,Galewski, Zbigniew
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p. 259 - 267
(2008/03/13)
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- Symmetrical and unsymmetrical analogues of isoxyl; active agents against Mycobacterium tuberculosis
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Symmetrical and unsymmetrical analogues of the antimycobacterial agent isoxyl-have been synthesized and tested against Mycobacterium tuberculosis H37Rv and Mycobacterium bovis BCG, some showing an increased bactericidal effect. In particular, compounds 1-(p-n-butylphenyl)-3-(4-propoxy-phenyl) thiourea (10) and 1-(p-n-butylphenyl)-3-(4-n-butoxy-phenyl) thiourea (11) showed an approximate 10-fold increase in in vitro potency compared to isoxyl, paralleled by increased inhibition of mycolic acid biosynthesis in M. bovis BCG. Interestingly, these isoxyl analogues showed relatively poor inhibition of oleate production, suggesting that the modifications have changed the spectrum of biological activity.
- Bhowruth, Veemal,Brown, Alistair K.,Reynolds, Robert C.,Coxon, Geoffrey D.,Mackay, Simon P.,Minnikin, David E.,Besra, Gurdyal S.
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p. 4743 - 4747
(2008/12/23)
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- Organosoluble copper clusters as precatalysts for carbon - Heteroelement bond-forming reactions: Microwave and conventional heating
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(Chemical Equation Presented). The coupling of aryl iodides with alcohols under mild conditions has been explored using self-assembled octanuclear copper clusters as catalysts. Reactions involving tetrahydrofurfuryl alcohol were typically complete in 4-8
- Manbeck, Gerald F.,Lipman, Adam J.,Stockland Jr., Robert A.,Freidl, Adrienne L.,Hasler, Amy F.,Stone, Joshua J.,Guzei, Ilia A.
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p. 244 - 250
(2007/10/03)
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- Positive allosteric modulators of the nicotinic acetylcholine receptor
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The invention provides compounds of Formula I: These compounds may be in the form of pharmaceutical salts or compositions, may be in pure enantiomeric form or racemic mixtures, and are useful in pharmaceuticals used to treat diseases or conditions in which α7 nAChR is known to be involved.
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- Mesogenicity of organophosphazenes: The effect of phosphazene rings and side groups on the phase transition
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Cyclotriphosphazene and cyclotetraphosphazene derivatives with mesogenic 4-N-(4-alkoxyphenyl)iminomethyl)phenoxy and 4-(4′-alkoxy) biphenoxy moieties were synthesized. Schiff base moiety has higher mesomorphic stability than that in biphenyl moiety both in cyclotriphosphazene and cyclotetraphosphazene. Cyclotriphosphazenes possess higher thermal stability in the mesomorphic phase than the cyclotetraphosphazenes, suggesting the difference in the molecular structure.
- Moriya, Keiichi,Yamane, Toshihiro,Suzuki, Toshiya,Masuda, Tsuyoshi,Mizusaki, Hiroshi,Yano, Shinichi,Kajiwara, Meisetsu
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p. 1427 - 1432
(2007/10/03)
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- Liquid crystalline properties of azobenzenes: I. 4-methoxy-, 4-ethoxy-, 4-propoxy-and 4-butoxy-4′-alkyloxyazobenzenes
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Liquid crystalline properties of four series of azobenzenes, 4-methoxy-4-alkyloxyazobenzenes (azo-1-n), 4-ethoxy-4′-alkyloxyazobenzenes (azo-2-n), 4-propoxy-4′al-kyloxyazobenzenes (azo-3-n) and 4-butoxy-4′-alkyloxyazobenzenes (azo-4-n), were investigated. By polarizing microscopy nematic and smectic C mesophases were detected. By DSC and TOA thermo-optics the parameters of phase transitions were measured. A typical odd-even effect of the clearing temperature was found. No smectic phase was detected in the first three series, even for the longest alkyloxy chains. The smectic C appears for the first time in the butoxy family, starting from the undecyloxyl derivative. In each series a polymorphism in the solid state was detected, especially significant in the propoxy and butoxy family, that was explained in terms of the ODIC phases.
- Galewski,Hofmanska,Zielinska
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p. 1357 - 1371
(2007/10/03)
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- Conformationally mobile wide rim Carbamoylmethylphosphine Oxide (CMPO)-calixarenes
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Six new calix[4]arene derivatives 2a-f have been synthesised, bearing CMPO-like functions (-NH-C(O)-CH2-P(O)Ph2) at their wide rim. They differ by their alkoxy groups at the narrow rim, comprising all possible combinations of methoxy and syn-propoxy groups including the conformationally mobile tetramethyl ether 2e and the tetrapropyl ether 2f fixed in the cone conformation. Their extraction behaviour for thorium(IV) and several lanthanides(III) from 1M HNO3 to dichloromethane has been studied and compared also to non cyclic calixarene analogues 6a-e. Surprisingly the best extraction results were found for the 1,2-dimethoxy-3,4-dipropoxy derivative 2c among the calixarenes and for the tetramer 6d among the linear compounds. Extraction of americium(III) in comparison to curium(III) and various lanthanides(LaIII), Ce(III), Nd(III), Sm(III), Eu(III)) from 0.1 - 3M HNO3 to NPHE (o-nitrophenyl hexyl ether) was most effective again for 2c. Among these cations, the highest distribution coefficients were found for Am(III) and the lowest for Ce(III) with a maximum generally in the range of 1-2M HNO3. Wiley-VCH Verlag GmbH, 1999.
- Matthews, Susan E.,Saadioui, Mohamed,Boehmer, Volker,Barboso, Silvia,Arnaud-Neu, Francoise,Schwing-Weill, Marie-Jose,Carrera, Alejandro Garcia,Dozol, Jean-Francois
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p. 264 - 273
(2007/10/03)
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- Convenient strategies for the preparation of modified 2(3H)-benzothiazolethiones
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4-Alkyl-2-bromoanilines and 4-alkoxy-2-chloroanilines were synthesized conveniently and submitted to cyclization reaction with potassium O-ethyl dithiocarbonate to afford 6-substituted 2(3H)-benzothiazolethiones in good yields.
- Chaudhuri, Narayan C.
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p. 3783 - 3790
(2007/10/03)
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- Mesogenic 4-(2,3-Epoxypropoxy)-4'-alkoxyazoxybenzenes
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Optimal conditions for preparation of 4-(2,3-epoxypropoxy)-4'-alkoxyazoxybenzenes were developed, and 10 mesogenic homologs (n = 1-10) possessing an extended nematic mesophase were synthesized.Nonyloxy and decyloxy derivatives of epoxyazoxybenzene exhibit also smectic mesomorphism.
- Burmistrov, V. A.,Kuz'mina, S. A.,Koifman, O. I.
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p. 351 - 353
(2007/10/03)
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- Mesogenic properties of liquid crystals having a chiral semiflexible joint
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Two homologous series of mesogenic enantiomers with chiral semiflexible joint, -C*H(CH3)CH2COO-, are examined. High twist power and presence of blue phases with short lattice period are found for eleven examined compounds. Some effects of chirality in reentrant system are discussed. On phase diagram of enantiomers the SmAd phase area is shifted toward longer homologues as compared to racemates. In result, an island of the SmAd phase in the cholesteric sea exists on binary phase diagrams of R- and S- enantiomers. Triple divergence of the pitch in the cholesteric phase of a pure compound is observed.
- Gorecha,Pyzuk,Mieczkowski
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- KINETICS OF ALKALINE HYDROLYSIS AND CORRELETION STUDIES OF m- AND p-SUBSTITUTED PIPERIDINOETHYL PHENYLCARBAMATES
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Kinetics of alkaline hydrolysis have been studied with a series of 15 m- and p-substituted piperidinoethyl phenylcarbamates.The rate constants have been determined at 70, 60, 50, and 40 deg C and the activation parameters have been calculated.These values have been correlated with the substituent constants ?, , , F, R, ?.Validity of the Hammett equation and the Swain-Lupton equation has been confirmed in the series studied and for the p-derivatives, respectively.The lipophilicity parameter ? does not correlate with the values found.
- Stankovicova, Maria,Cizmarik, Jozef
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p. 1846 - 1853
(2007/10/02)
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- GRAPHITE CATAlYZED REDUCTION OF AROMATIC AND ALIPHATIC NITRO COMPOUNDS WITH HYDRAZINE HYDRATE
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Aromatic and aliphatic nitro compounds were readily reduced to amino compounds in excellant yields with graphite and hydrazine hydrate.
- Han, Byung Hee,Shin, Dae Hyun,Cho, Sung Yun
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p. 6233 - 6234
(2007/10/02)
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- NOVEL TRANSETHERIFICATION IN CATALYTIC REDUCTION OF 4-ALKOXYNITROBENZENES IN ALCOHOL-SULFURIC ACID SOLUTION
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In catalytic reduction (5percent Pt-C, 1 atm H2) of 4-alkoxynitrobenzenes (R1O-C6H4-NO2) in alcohol(R2OH)-sulfuric acid solution at room temperature, the reduction was found to be accompanied by transetherification to afford R2O-C6H4-NH2.
- Sone, Takaaki,Teraoka, Tadayoshi,Katada, Sho-ji,Ohkubo, Makoto,Karikura, Masami,et al.
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p. 1259 - 1262
(2007/10/02)
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