13476-68-1Relevant academic research and scientific papers
Two efficient routes to m-terphenyls from 1,3-dichlorobenzenes
Saednya, Akbar,Hart, Harold
, p. 1455 - 1458 (1996)
In the first route 2,6-dichlorophenyllithium (5), prepared by direct lithiation of 1,3-dichlorobenzene, reacted with aryl Grignard reagents to give m-terphenyls in 57-93% yields; the methodology was extended to substituted 1,3-dichlorobenzenes (i.e. 8 → 10). Also, reaction of 5 with MgCl2 gave 2,6-dichlorophenyl-magnesium chloride which, on warming, produced the self-capture product tetrachloro-m-terphenyl 7 in moderate yield. In the second route, reaction of 1,3-dichlorobenzene with excess of aryllithium in diethyl ether at room temperature gave the corresponding m-terphenyls in 59-94% yields. Examples are given in which the aryllithium was prepared by three different routes (ArX + Li, ArX + t-BuLi, ArH + BuLi).
Javelin-, hockey stick-, and boomerang-shaped liquid crystals. Structural variations on p-quinquephenyl
Dingemans, Theo J.,Murthy, N. Sanjeeva,Samulski, Edward T.
, p. 8845 - 8860 (2007/10/03)
The ramifications of changing molecular geometry in a series of all-aromatic liquid crystals derived from p-quinquephenyl are reported. Substituting heterocyclic rings such as thiophene, oxadiazole, oxazole, or 1,3-phenylene into the p-quinquephenylene core affects molecular shape changes via the substituent's exocyclic bond angle. In general, we found that introducing nonlinearity into molecules depresses the melting transition temperature. The symmetric (boomerang-shaped) molecules, 2,5-bisbiphenyl-4-yl-1,3,4-oxadiazole, 2,5-bisbiphenyl-4-yl-oxazole, and 1,3-bisbiphenyl-4-yl-benzene, melt into isotropic phases showing small monotropic mesophases. By contrast, the asymmetric (hockey stick-shaped) mesogens, 2-terphenyl-4-yl-5-phenyl thiophene and 2-terphenyl-4-yl-5-phenyl-1,3,4-oxadiazole, exhibit more stable enantiotropic liquid crystalline phases. The hockey stick-shaped mesogens exhibit a smectic phase as well as a nematic phase. High-temperature X-ray determination of the smectic layer spacing gives an unambiguous picture of interdigitated, bilayerlike supramolecular architecture in the smectic phase. There are associated changes in the mesogen's electrostatic profile when a heterocycle is introduced into the quinquiphenylene framework (e.g., conjugation is perturbed). Our findings suggest that steric packing considerations dominate the phase preferences (nematic versus smectic phases). However, electronic considerations (conjugation) appear to control the range of mesomorphism in this new family of nonlinear liquid crystals.
A One-Pot Synthesis of m-Terphenyls via a Two-Aryne Sequence
Du, Chi-Jen Frank,Hart, Harold,Ng, Kwok-Keung Daniel
, p. 3162 - 3165 (2007/10/02)
Aryl-Grignards (3+ equiv) react with 2,6-dibromoiodobenzene or other 1,2,3-trihalobenzenes to give 2,6-diarylphenylmagnesium halides.The mechanism involves Grignard exchange at the central halogen, followed by two cycles of magnesium halide loss and regioselective capture of the resulting aryne by the aryl-Grignard reagent (Scheme I).Typical examples are shown in Table I.The method is especially applicable to m-terphenyls in which the "outer" rings are identical and/or in which substitution at the 2' or other positions of the "central" ring is desired.
Syntheses and Spectral Properties of Several Branched-chain Polyphenyls containing 1,3,5-Trisubstituted Ring(s)
Ozasa, Shigeru,Fujioka, Yasuhiro,Hashino, Hiromi,Kimura, Naoko,Ibuki, Eiichi
, p. 2313 - 2320 (2007/10/02)
Six polyphenyls, including four new compounds, 5',5''-di(2-biphenylyl)-2,2'''-diphenyl-m-quaterphenyl (3), 2,5',2''-triphenyl-m-terphenyl (4), 3,5-di(2-biphenylyl)-o-terphenyl (5), and 5''-(3-biphenylyl)-m-quinquephenyl (6), were synthesized by the Ullmann coupling reaction of iodo compounds.Proton magnetic resonance spectral studies indicated that the characteristic spectral features of the polyphenyls containing 1,3,5-trisubstituted ring system(s) were fully compatible with their conformational aspects deduced from stereomodels.Ultraviolet spectral data indicated that the dihedral angle of the pivot bond of the branched ring in the polyphenyls in solution is very similar to that of biphenyl.Keywords - Ullmann reaction; quinquephenyl; sexiphenyl; septiphenyl; decaphenyl; polyphenyl; IR; UV; 1H-NMR
Studies of Polyphenyls and Polyphenylenes. II. The Synthesis and Physical Properties of Polyphenyls Containing Para Linkage
Ozasa, Shigeru,Hatada, Noriko,Fujioka, Yasuhiro,Ibuki, Eiichi
, p. 2610 - 2617 (2007/10/02)
Twelwe linear polyphenyls, including quinque- to octiphenyl, were synthesized by the Ullmann cross-coupling reaction of iodobiphenyl with diiodobenzene or iodoterphenyl.Ultraviolet spectral studies of the polyphenyls indicated that the positions of the K-bands above ca.260 nm, regardless of the presence of o- or m-phenylene unit(s), may be considered to be an indication of the approximate number of consecutive p-phenylene units.Infrared studies also showed that the locations of strong or medium bands in the 815-850 cm-1 region may give the same information.The HMO calculations of the longest wavelength absorption bands of twenty-four polyphenyls were carried out.A comparison between the calculated and observed wavelengths gave rather good agreement, except in the cases of two compounds.The signals of the proton magnetic resonanse spectra of eighteen polyphenyls were assigned tentatively.The correlations between the arrangement of the benzene rings and the spectral patterns are discussed.
