Effect Of Fluoro Substituents Research Articles

Regiocontrol Using Fluoro Substituent on 3,6-Disubstituted Arynes.

The effect of fluoro substituent on the regioselectivity of several reactions of 3,6-disubstituted arynes was studied. These arynes contained another inductively electron-withdrawing substituent other than fluorine. A reasonable degree of regiocontrol was achieved in the (3 + 2) cycloaddition reaction of 3,6-disubstituted aryne containing both fluorine and bromine atoms with benzyl azide. Furthermore, the insertion reaction of aryne into Sn-F σ-bonds and the three-component coupling reaction involving the insertion of aryne into C=O π-bonds also led to the high degree of regiocontrol.

Effect of Fluoro Substituents on Polynitroarylenes: Design, Synthesis and Theoretical Studies of Fluorinated Nitrotoluenes.

The replacement of traditional polynitroarylenes by their fluorinated derivatives has attracted great attention due to the improvements on detonation performance caused by the fluorine effect. A straightforward synthesis of three novel fluorinated nitrotoluenes with different degrees of nitration was achieved under selected high temperatures. The fluorine exerted remarkable influence on the nitration process through the electron-withdrawing effect and a mechanism of the transformation was proposed according to the experimental results. Thermal decomposition behavior of the fluorinated nitrotoluenes was investigated by differential scanning calorimetry and all the compounds showed ideal low melt points for the melt-cast process. X-ray analysis of the fluorinated derivatives were carried out as well as density functional calculations to establish the electronic density and electrostatic potential on the molecular surface of the optimized structures. The good thermal and detonation properties make the newly developed fluorinated nitrotoluenes possible replacements for trinitrotoluene and dinitrotoluene in the formation of melt-cast energetic materials.

Efficient Implementation of Energy Decomposition Analysis for Second-Order Møller-Plesset Perturbation Theory and Application to Anion-π Interactions.

Energy decomposition analysis (EDA) is a widely used tool for extracting physical and chemical insights from electronic structure calculations of intermolecular interactions, as well as for the development of advanced force fields for describing those interactions. Recently, the absolutely localized molecular orbital (ALMO) EDA has been extended from the self-consistent field level to the second-order Møller-Plesset (MP2) theory level. This paper reports an efficient implementation of the MP2 ALMO-EDA that scales optimally, employs the resolution of the identity (RI) approximation for post-SCF matrix elements, and is shared-memory parallel. The algorithms necessary to achieve this implementation are described in detail. Performance tests using the aug-cc-pVTZ basis set for water clusters of up to 10 molecules are reported. The timings suggest that the MP2 ALMO-EDA is computationally feasible whenever MP2 energy calculations themselves are feasible, and the cost is dominated by the SCF itself in this size regime. The MP2 ALMO-EDA is applied to study the origin of substituent effects in anion-π interactions between chloride and benzene and mono- through hexafluorobenzene. The effect of fluoro substituents was primarily to change the frozen interaction. Detailed analysis supports the interpretation that anion-π interactions are favorable because of electrostatic interaction with the substituents.

(L)乳酸手性衍生物的含氟二苯乙炔液晶的合成

1-[(1-ethoxycarbonyl)-ethyl]-4-[4-(2,3,5,6-tetrafluoro-4-alkoxy-phenyl)ethynyl)-phenyl] terephthalates have been synthesized(n=5,6,7,8)and studied by thermal polarizing microscopy and DSC measurement.The effect of fluorosubstituent and bridge on the mesomorphic properties were discussed.These compounds exhibit enantiotropic cholesteric phase and low viscosity high birefringence and chemical stability.These compounds can be used for reflective LCDs and adaptive optics system.The target compounds were synthesized by Sonogashira cross coupling.

Electronic Effect of Fluoro Substituents on Chromium(III) Complexes bearing β-Diketiminate Ligands for Ethylene Polymerization

A series of new chromium(III) complexes bearing fluoro-substituted β-diketiminate ligands have been synthesized and characterized by IR and elemental analyses. When activated by modified methylaluminoxane (MMAO), these Cr complexes exhibited moderate or high activities for ethylene polymerization (up to 370 g.mmol-1.h-1). Various reaction parameters such as reaction temperature and Al/Cr ratio were investigated in detail. Further more, it was found for the first time that the catalytic behaviors of Cr complexes can be greatly influenced by the electronic effect of fluoro substituents. The introduction of electron-withdrawing fluoro groups to ligands can improve the catalytic performances compared with those bearing alkyl groups, but incorporation of more fluoro atoms would then decrease the catalytic activities.

Effect of lateral fluoro substituents on the chiral liquid crystal materials derived from (S)‐1‐methyl‐2‐(2′‐methylsulphanylethoxy)ethanol

Two series of chiral materials, the (R)‐1‐methyl‐2‐(2′‐methylsulphanylethoxy)ethyl 4‐(4′‐alkoxybiphenyl‐1‐carboxyloxy)‐2‐fluorobenzoates, 2F3H(m = 7–10), and the (R)‐1‐methyl‐2‐(2′‐methylsulphanylethoxy)ethyl 4‐(4′‐alkoxybiphenyl‐1‐carboxyloxy)‐3‐fluorobenzoates, 2H3F(m = 7–10), were synthesized for investigation. Polymorphism of the materials was detected primarily by polarizing microscopy and differential scanning calorimetry. The ferroelectric and antiferroelectric phases were further characterized by switching current behaviour, electro‐optical response and dielectric permittivity. The results show that the antiferroelectric phase occurred in two materials, 2F3H(m = 7) and 2H3F(m = 8). The spontaneous polarization and apparent tilt angle for the materials in the SmC* and/or phases were also measured. The effect of fluoro substituents on the physical properties of the materials is discussed.

Effect of fluoro substituents and central atom nature on chiral derivatives of bisdiphenylborates and isoelectronic structures

A DFT study of the geometrical, electronic, and energetic parameters of homo- and heterochiral complexes of fluoro derivatives of diphenylborate and isoelectronic structures where the central atom has been substituted by carbon and nitrogen has been carried out. The results have allowed correlation of the relative energies (hetero- minus homochiral complex) versus the presence of fluorine in the different positions on the aromatic rings and the presence of different central atoms. Other correlations between geometrical parameters and the relative energy have also been found. Some of the predictions have been confirmed with the calculation of new derivatives.

ChemInform Abstract: Effects of Fluoro Substituents on Excited State Properties of Conjugated Polyenes (Fluorinated Retinoids)

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Photoreactions of 3,4,5,6‐Tetrafluoro‐N‐methylphthalimide with Alkenes. Effect of Fluoro Substituents on the Photoreaction Pathway.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Skin tumor initiating activities of the 9- and 10-fluoro derivatives of 7- or 12-methylbenz[a]anthracene and the 9- and 10-trifluoromethyl derivatives of 7,12-dimethylbenz[a]anthracene in SENCAR mice.

We have determined the skin tumor initiating activity in SENCAR mice of several 9- and 10-substituted mono- and dimethylbenz[a]anthracene derivatives. 9-fluoro-7-methylbenz[a]anthracene (9-F-7-MBA) was approximately as active as 7-MBA, whereas 10-F-7-MBA was considerably more active as a skin tumor initiator than the parent compound. Initiating doses of 200 and 400 nmol per mouse of 10-F-7-MBA yielded 14.17 +/- 0.16 and 22.47 +/- 1.64 papillomas per mouse after 18 weeks of promotion with 12-O-tetradecanoylphorbol-13-acetate, whereas comparable doses of 7-MBA yield 2.13 +/- 0.12 and 4.73 +/- 0.68 papillomas per mouse respectively. The effect of fluoro substituents at positions 9 and 10 of 12-MBA, a less potent tumor-initiator than 7-MBA, was also examined. 9-F-12-MBA was only slightly more active than 12-MBA, whereas 10-F-12-MBA was again considerably more active than the parent compound. Doses of 400 and 800 nmol per mouse of 10-F-12-MBA yielded 24.97 +/- 2.18 and 22.20 +/- 6.47 versus 1.13 +/- 0.80 and 3.00 +/- 0.17 papillomas per mouse respectively for comparable initiating doses of 12-MBA. The effect of introducing a trifluoromethyl (CF3) group at the 9 and 10 positions of 7,12-dimethylbenz[a]anthracene was also examined. A CF3 group at either of these positions essentially eliminated the tumor initiating activity of DMBA at the doses tested. These results when taken together with previous results from our laboratory suggest that electron donating substituents at positions 9 and 10 of the benz[a]anthracene nucleus either have no effect or enhance skin tumor initiating activity, whereas electron withdrawing groups at these positions dramatically reduce or abolish tumor initiating activity.