Effect Of Phenyl Group Research Articles

Enantio- and Diastereoselective Michael Addition of Cyclic Ketones/Aldehydes to Nitroolefins in Water as Catalyzed by Proline-Derived Bifunctional Organocatalysts.

New l-proline-derived bifunctional secondary amine organocatalysts were synthesized for enantioselective Michael reactions in water as a solvent. Application of these catalysts in Michael additions provided high yield (up to 97%) with high stereoselectivity (dr up to 99:1 and ee up to 99%). The effect of phenyl group at (R)-C6 in the catalyst was investigated and played a key role in successful catalysis by density functional theory computational calculations. The synthetic utility of this reaction was demonstrated by the formal synthesis of Sch 50971, which is a novel histamine H3 receptor agonist.

Visualizing the effect of phenyl group on the intra-or intermolecular vibrational dynamics of nitromethane, nitrobenzene and their mixtures by coherent anti-Stokes Raman scattering

Visualizing the effect of phenyl group on the intra-or intermolecular vibrational dynamics of nitromethane, nitrobenzene and their mixtures by coherent anti-Stokes Raman scattering

Micellization of trisiloxane surfactants appended with phenyl groups and polyether in aqueous solution

Polyether based trisiloxane surfactants with phenylsiloxyl hydrophobic groups (Ph-Si3-PG and Ph2-Si3-PG) were successfully synthesized and confirmed by 1H NMR, 13C NMR, 29Si NMR, and FT-IR. The effect of phenyl groups on the micellization and adsorption behavior in aqueous solution were investigated by surface tension, dynamic light scattering (DLS), freeze-fracture transmission electron microscopy (FF-TEM), transmission electron microscopy (TEM), and steady-state fluorescence spectroscopy. The γCMC values of Ph-Si3-PG and Ph2-Si3-PG obviously increase resulting from the phenylsiloxyl groups grafting onto the trisiloxane hydrophobic groups. The γCMC values follow the order, Ph-Si3-PG (35.5 mN·m−1) < Ph2-Si3-PG (39.7 mN·m−1), and the CMC values follow the order, Ph-Si3-PG > Ph2-Si3-PG. The results of steady-state fluorescence spectroscopy show that Ph2-Si3-PG has smaller I1/I3 value attributed to the more hydrophobic solubilizing site for the pyrene probe. Ph-Si3-PG and Ph2-Si3-PG can form non-uniform size of spheroidal aggregates in aqueous solution and confirmed by FF-TEM and TEM.

ヒドロペルオキシアルキルラジカルのβ分解反応にフェニル基が与える影響

ヒドロペルオキシアルキルラジカルのβ分解反応にフェニル基が与える影響

The effect of phenyl groups on the transport properties of tetracene molecule

Electronic transport properties of pure tetracene and rubrene molecules were studied using density functional theory within the non-equilibrium Green's function method. Transmission coefficient and I-V curve were calculated for both molecules. The comparison between transmission coefficients in tetracene and rubrene molecules shows that there are some extra peaks in rubrene that belong to phenyl rings which are attached to tetracene. Besides, we found that up to 2.2V the current is almost the same in both rubrene and tetracene and above this value, the current in rubrene is increased in comparison to tetracene which is the result of attachment of additional phenyl groups in rubrene molecule. Finally, we detected that these two molecules exhibit negative differential resistance behavior in the range between 1.2V and 2V.

Structures and photophysical properties of copper(I) complexes bearing diphenylphenanthroline and bis(diphenylphosphino)alkane: the effect of phenyl groups on the phenanthroline ligand.

A series of copper(I) complexes bearing 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (dmpp) and a diphosphine ligand have been prepared. The diphosphine ligands used have two, three or four methylene carbons between the two phosphorus atoms. The crystallographic study has revealed that two of the three complexes have the mononuclear structure bearing dmpp and a bidentate diphosphine ligand, and one is a diphosphine-bridged binuclear complex. The photoluminescence of the complexes in solution was studied and compared with the previously reported complexes bearing 2,9-dimethyl-1,10-phenanthroline (dmp). It was found that the two phenyl groups on the phenanthroline ligand have a marked effect on the photophysical properties of the complexes; the intensity of the emission of the complexes is greatly enhanced by the phenyl groups. The photophysics of the complexes is discussed with the results of DFT and TDDFT calculations.

Reductive Alkylation of Pentaphenylthiopyrylium Perchlorate: An Approach to Regiospecific Synthesis of Hexasubstituted 2H-Thiopyrans

Regiospecific synthesis of some new hexasubstituted 2H-thiopyrans was examined by reductive alkylation of pentaphenylthiopyrylium perchlorate and found to be in quantitative yields. Under our experimental conditions, the formation of unstable thiabenzene intermediates could be observed through detectable color changing during the addition of C-nucleophiles to thiopyrylium perchlorate. Moreover, the effect of phenyl groups on the 3,5-positions of thiopyrylium perchlorate on the regioselectivity were compared with other analogs having methyl groups on the same positions.

Effect of phenyl group on the structure and formation of transitional alumina from Al (OPh)3

The structure of freshly prepared Al(OPh)3, its decomposition product, the hydrolyzed products and their structural evolution were investigated employing 27Al MAS NMR spectroscopy, PXRD, TGA/DTA/DSC/FTIR techniques. In the 27Al MAS NMR spectrum of the aluminium phenoxide, three signals with the chemical shift at 3.78, 21 and 45 ppm were observed. The chemical shift at 3.78 and 45 ppm revealed the presence of four and sixfold coordinated aluminum. The signal at 21 ppm corresponded to fivefold coordinated aluminium. When the aluminium phenoxide was directly decomposed in air at 600 °C, it resulted in amorphous product as evidenced from the PXRD pattern. The observed signals with chemical shifts at 10.1, 42, 73.6 ppm in the 27Al MAS NMR spectrum indicated the presence of 6, 5 and 4 coordination for the aluminium atoms suggesting disordered transitional γ-alumina to be the product. The hydrolysis studies of Al(OPh)3 with excess of water at 70 °C yielded bohemite (γ-AlOOH). The alumina obtained after dehydration at 600 °C was X-ray amorphous. The dehydrated product at 600 °C showed the presence of four and six coordinated aluminium atoms in the 27Al MAS NMR spectrum confirming it to be ordered γ-Al2O3. Crystalline γ-Al2O3 was obtained on further heating at 800 °C.

Effect of phenyl group on the self assembly of N, N′- bis-(2-phenylglycinyl)pyromellitic diimide with aromatic hydrocarbons

The presence of the phenyl substituent in N, N′- bis-(2-phenylglycinyl)pyromellitic diimide ( L2) facilitate the aromatic C H⋯π interactions of the guests such as anthracene and perylene and play the crucial role in directing the hydrogen bonding motif involving the carboxylic acid groups of L2.

Synthesis, X-ray, and DFT Study of the Double-Bond Pyramidalization in 1,7,8,9-Tetraphenyl-4,10,10- trimethyl-4-aza-10-silatricyclo[5.2.1.0.2,6]deca-8-ene-3,5-dione and Its Germanium Analogue

Diels-Alder adducts of 1-sila-2, 3, 4, 5-tetraphenyl-1, 1-dimethyl-2, 4-cyclopentadiene and 1-germa-2, 3, 4, 5-tetraphenyl-1, 1-dimethyl-2, 4-cyclopentadiene with N-methylmaleimide and maleic anhydride were prepared by high pressure reactions. Their X-ray structures were determined and compared to literature data. In addition, B3LYP/6-31G* method was used to study their molecular and electronic structure. X-ray analysis revealed that extent of pyramidalization of the double bond in all studied compounds is small (molecules 1 and 2) or negligible (3). B3LYP/6-31G* calculations were found to overestimate pyramidalization by 5.3 to 9.4 degrees, presumably due to crystal packing forces. The effect of phenyl groups on geometry of the double bond is discussed.

Effect of aromatic protectors on the radiolysis of polyorganosiloxanes

The influence of phenyl and other aromatic groups on radiation crosslinking of polydimethylsiloxane and its mechanical blends and copolymers with polydiphenylsiloxane and polyphenylsilsesquioxane, radiation-induced gas evolution, and radical generation in these systems were considered. It was shown that radiation-chemical yields of crosslinking and gas evolution follow a simple exponential law over a wide concentration range of phenyl groups (at their content above 1 mol %). A similar dependence was observed for the radiation-chemical yield of hydrogen in ethylene copolymers with styrene. For the crosslinking processes, it was proved that the effect of phenyl groups is identical in the mechanical blends and copolymers of polyorganosiloxanes. The effect of retardation of radiation-chemical processes by phenyl groups was shown to be independent of whether one or two groups is linked to a silicon atom, it is their total amount that matters.

Relationship of Structure to Properties of Some Anionic Surfactants as Collectors in the Flotation Process. 2. Effect of Phenyl Group

Surface and thermodynamic properties of four synthetic anionic surfactants are studied. The properties of these surfactants are correlated with their flotation performance to upgrade a petroleum coke sample to minimize its impurities. The surfactants are isomers for dodecylbenzenesulfonate of the same molecular weight, but the benzene ring is attached to different carbon atoms along the dodecyl chain. The results show that the position of benzene ring, attached to the carbon chain, affects their surface and thermodynamic properties. The values of critical micelle concentration (cmc), minimum area per molecule (Amin), effectiveness (Πcmc), and efficiency (pC20), to reduce surface tension of water, are decreased with changing the position of benzene ring from carbon atom number 3 to 5. Increasing temperature is accompanied by an increase in each of cmc, minimum area per molecule (Amin), Gibbs energy of micellization (ΔG°mic), and adsorption (ΔG°ad). Meanwhile, the values of surface tension (γcmc) at cmc, surface excess concentration (Γmax), and effectiveness (Πcmc) to reduce surface tension of water are decreased. There is a good relationship between the structure of a surfactant and its efficiency as a collector. Changing the position of the phenyl group along the alkyl chain of a surfactant toward its central carbon atom (6φC12) improves its efficiency as a collector.

Cyclopolymerization. XIX. Effect of N‐substituents on cyclopolymerizability of N‐allylmethacrylamides

AbstractThe effect of bulky N‐substitutents of N‐t‐butyl‐ and N‐phenyl‐N‐allylmethacrylamides (BAMA and PAMA, respectively) on their cyclopolymerizability was investigated. BAMA yielded an almost completely cyclized polymer while the degree of cyclization of poly (PAMA) was about 95%. The latter value indicates that the effect of phenyl group is comparable with that of methyl group, since N‐methyl‐N‐allylmethacrylamide was reported to give a polymer with a degree of cyclization of 93%. Structural investigation on telomerization products of BAMA and PAMA permitted the assignment of the repeating cyclic units of these polymers to that of a five‐membered ring. This structural characteristic was also supported by the observation of five‐membered cyclized radicals on ESR measurements of these monomers. Rotation around amide CN bonds of these monomers and related compounds studied by 13C‐NMR was found to be strongly dependent on N‐substitutents. The mechanism of the cyclization was discussed in terms of the structure of the ring formed and rotation around amide CN bonds of these monomers. The reactivity of the methacryloyl and allyl groups involved in these monomers were compared based on the information obtained by structural investigation of polymers and telomerization products and by ESR studies. © 1993 John Wiley &amp; Sons, Inc.

Kinetics and regioselectivity of the Autoxidation of Alkylaromatic Hydrocarbons

Conclusions concerning the reactivities of alkylaromatic hydrocarbons in autoxidations are possible neither on the basis of the oxidizabilities nor on the basis of the chain propagation constants kp. In order to compare different alkylaromatic hydrocarbons, their rate constants with a definite peroxy radical, for example with the cumylperoxy radical, must be determined. Another possibility is the evaluation of relative rate constants by competitive oxidations of binary mixtures of hydrocarbons. These constants are not related to a definite peroxy radical. Nevertheless, these relative rate constants are real measures of the reactivities. If one also determines the composition of the reaction mixtures, which is especially convenient after LiAlH4 reduction, then it is possible to evaluate relative reactivities of the single C-H bonds, for example in relation to the tertiary C-H bond of cumene. This was done in our studies, and a great number of single bond reactivities is given in this survey. It is therefore possible to evaluate the activating effect of phenyl groups on different types of α-C-H bonds, and steric effects are also perceptible. In o-substituted isopropyl aromatics, a desactivation by steric hindrance of mesomerism takes place.

Effects of Phenyl Groups on Thermodynamic Parameters of Lanthanoid(III) Complexation with Aromatic Carboxylic Acids

Abstract The enthalpy changes as well as the stability constants of the complexes between a series of lanthanoid(III) cations and phenylacetate, 3-phenylpropionate, and salicylate ions have been measured using a potentiometer and an isothermal calorimeter, respectively. The data were compared with the data with benzoate ions. The enthalpy changes for formation of the heavier lanthanoid(III) complexes are larger than those for the complexation of the lighter lanthanoids. Also, the complexation heat changes by the carboxylate ions having methylene group(s) between the carboxyl and the phenyl groups are more endothermic than by the anions in which these two groups are joined directly. The results are explained in terms of the differences in the dehydration of the lighter lanthanoid(III) from that of the heavier ones upon complexation and also the different basicities of the carboxylate ions of the ligands.

Effect of phenyl groups on relaxational processes in polystyrene and polybutadiene methylstyrenes

The phenyl side groups in both polystyrene and polybutadiene are responsible for two types of relaxational transitions. The first (γ-relaxation) is related to rotational-torsional motions of free phenyl groups (fast relaxation), whereas the second (μ-relaxation) is related to the decay and recombination of physical cross-links formed as a result of the coupling of phenyl groups (slow relaxation).

A novel oxidative reaction of 2,4,5‐triphenylpyrrole

AbstractThe effect of phenyl groups on the oxidation of 2,4,5‐triphenylpyrrole (I) has been investigated. By oxidation of 2,4,5‐triphenylpyrrolemagnesium bromide (II) with oxygen and of 2,4,5‐triphenylpyrrole (I) with potassium permanganate besides 2,4,5,2′,4′,5′‐hexaphenyl‐3,3′‐bi‐pyrrole (III) another product, which has been assigned the 1,6‐dihydro‐2,3,4,5,6a‐pentaphenylbenzo[g]pyrrole[3,2‐e]indole (IV) structure, was obtained. The behaviour of IV toward further oxidation and the spectroscopic data (ir, nmr, ms) were in good agreement with the assigned structures.

Substituent Effects in 1, 3, 5-Triazine Derivatives

Substituent effects in 1, 3, 5-triazine derivatives were measured by alcoholysis of chlorotriazine derivatives and by proton NMR spectra. The effects of substituents on methoxyl C-H coupling constants were also measured. Using the substituent constants in, the Hammett equation was satisfied in several cases. However, large 'deviations were observed in the cases of phenyl and phenoxy substituted triazines. It seems that deviations are caused by the diamagnetic anisotropy -effect of phenyl group and by the inaccuracy of the substituent constant of phenoxy group.

Charge-transfer spectra of pyrylium iodides

New methods are described for the preparation of substituted pyrylium halides. Pyrylium iodides have a different colour and an additional charge-transfer absorption band in the crystalline state and in dichloromethane solution as compared with the corresponding perchlorates. The position of the CT band is intermediate between that of tropylium and pyridinium halides. The effect of phenyl groups on the CT band of pyrylium iodides, which is markedly different from the effect on the x-band from the absorption spectrum or on the polarographic half-wave potentials is tentatively explained by the symmetry properties of the lowest empty molecular orbital, thus accounting for the correlation with the y-band from the absorption spectrum.