Successive electron transfer reaction of the lithium salt of 5-methyl-5,10-dihydrophenazine anion with 4-nitrophenethyl bromide via 4-nitrostyrene

The reaction of lithium salt of 5-methyl-5,10-dihydrophenazine anion with 4-nitrophenethyl bromide in 1,2-dimethoxyethane gave unexpected compounds, 1,2-bis[5-(10-methyl-5,10-dihydrophenazinyl)]-1-(4-nitrophenyl)ethane and 1,4-bis(4-nitrophenyl)-1,4-bis[5-(10-methyl-5,10-dihydrophenazinyl)]butane, while the reaction in dimethyl sulfoxide brought about the formation of 5-methyl-10-(4-nitrophenethyl)-5,10-dihydrophenazine. The successive electron transfer mechanism is proposed for the former reaction via 4-nitrostyrene.     

Kinetics and mechanism of the thermal decomposition reaction of dihydro-3,6-diphenyl-5-benzyl-1,2,4,5-trioxazine

The thermal decomposition reactions of dihydro-3,6-diphenyl-5-benzyl-1,2,4,5-trioxazine (DHT) in the initial concentrations and temperature ranges of 0.004–0.013 M and 353–393 K, respectively, have been investigated in benzene, toluene, and methanol solutions. In these solvents the reaction follows a first-order kinetic law up to ca. 50% DHT conversions. However, at the higher temperatures and higher initial concentrations, an induced decomposition reaction of the DHT molecule is observed, which is suppresed by the addition of a free radical scavenger. The pseudo-first-order rate constant values for the reactions of the trioxazine in acetic acid solution (0.004 M) in the temperature range of 313–323 K, lead to activation parameters significantly different from those of the unimolecular thermolysis in other media. This supports a marked effect of the solvent on that reaction. The kinetics and the nature of the products observed in the DHT thermolysis favors a general stepwise mechanism of decomposition which resembles the type of reaction already postulated for other cyclic peroxides in solution. © 1996 John Wiley & Sons, Inc.     

New metallomesogenic polymers built by self-assembly of non-mesomorphic stilbazole dimers and CF3SO3Ag through coordination bonds

Supramolecular liquid-crystalline main-chain polymers have been obtained by self-assembly of non-mesomorphic bifunctional ligands and a transition metal ion. Stibazole dimers, bis[2-(2-{4-[2-(4-pyridyl)vinyl]phenoxy}ethoxy)ethyl] ether (1) and 1,2-bis[2-(2-{4-[2-(4-pyridyl)vinyl]phenoxy}ethoxy)ethoxy]benzene (2) have been synthesized and complexed with silver trifluoromethanesulfonate (CF₃SO₃Ag). The metallomesogenic polymeric complexes formed by coordination bonds between the pyridyl groups of the stilbazole dimers and the silver ion exhibit smectic phases.     

Synthesis and properties of germanium-containing poly(diphenylacetylenes)

1-Phenyl-2-[m-(trimethylgermyl)phenyl]acetylene (m-Me₃GeDPA) and 1-phenyl-2-[p-(trimethylgermyl)phenyl]acetylene (p-Me₃GeDPA) polymerized with TaCl₅–cocatalyst systems to provide in high yields new polymers having weight-average molecular weights over 1 × 10⁶. Poly(m-Me₃GeDPA) was a yellow solid, which completely dissolved in toluene, chloroform, etc., to form a tough film by solution casting. Poly(p-Me₃GeDPA) was also a yellow solid and partly insoluble in any solvents. The onset temperatures of weight loss for these polymers in the thermogravimetric analysis in air were as high as ca. 400°C. The oxygen permeability coefficient of poly(m-Me₃GeDPA) was 1100 barrers (25°C), which is about twice that of poly(dimethylsiloxane). © 1996 John Wiley & Sons, Inc.     

Periodic structure during unidirectional solidification for peritectic Cd–Sn alloys

Unidirectional solidification for the peritectic Sn–1.0, 1.5, 2.0 at% Cd alloys was carried out under temperature gradients of 2.7×10³ K/m for 4 mm diameter specimens, and 5.3×10³ K/m for 2 mm diameter specimens. A banded structure in which the two constituent phases alternatively form perpendicular to the growth direction was observed in the 2 mm diameter specimens. On the other hand, a competitive microstructure was obtained in the 4 mm diameter specimens, in which the two phases interlace and the three-phase junction fluctuated in the radial direction during unidirectional solidification. Formation of the banded structure depended on the specimen diameter, while the transition from the cellular interface to the planar interface was not affected by the specimen diameter. In the high G/V region for peritectic alloys, the growth morphology in which the phases grow side by side is unstable, even if the pulling rate and temperature profile are constant. The banded structure and the competitive structure originate through the same mechanism; this is intrinsic for peritectic alloys with two-phase composition.     

Pennelliiside D,a New Acyl Glucose from Solanum pennellii and Chemical Synthesis of Pennelliisides

Acyl glucoses are a group of specialized metabolites produced by Solanaceae. Solanum pennellii, a wild-type tomato plant, produces acyl glucoses in its hair-like epidermal structures known as trichomes. These compounds have been found to be herbicides, microbial growth inhibitors, or allelopathic compounds. However, there are a few reports regarding isolation and investigation of biological activities of acyl glucoses in its pure form due to the difficulty of isolation. Here, we report a new acyl glucose, pennelliiside D, isolated and identified from S. pennellii. Its structure was determined by 1D NMR and 2D NMR, together with FD-MS analysis. To clarify the absolute configuration of the acyl moiety of 2-methylbutyryl in the natural compound, two possible isomers were synthesized starting from β-D-glucose pentaacetate. By comparing the spectroscopic data of natural and synthesized compounds of isomers, the structure of pennelliiside D was confirmed to be 3,4-O-diisobutyryl-2-O-((S)-2-methylbutyryl)-D-glucose. Pennelliiside D and its constituent fatty acid moiety, (S)-2-methylbutanoic acid, did not show root growth-inhibitory activity. Additionally, in this study, chemical synthesis pathways toward pennelliisides A and B were adapted to give 1,6-O-dibenzylpennelliisides A and B.     

Synthesis of hyperbranched polymers via proton‐transfer polymerization of acrylate monomer containing two hydroxy groups

The hyperbranched polymer 2 was produced via triphenylphosphine initiated polymerization of the acrylate monomer 1 containing two hydroxy groups. The reaction resulting in 2 is based on a Michael‐type addition followed by a proton‐transfer process. The molecular weights evaluated by VPO measurements were vanging between 1 170–2 700 g/mol. The results of the methanolysis experiments of the polymers were used to determine the degrees of branching, that ranged between 0.45 and 0.60. In this polymerization, the hydroxy groups of the monomer and of the polymer are latent propagating species, which are converted into the corresponding anions, which are the actual propagating species active during the proton‐transfer reactions. The proton‐transfer occur frequently during this polymerization in order to afford the formation of hyperbranched polymers.     

Direct aldol reaction of trifluoroacetaldehyde ethyl hemiacetal with ketones by use of the combination of amines and acids

Trifluoroacetaldehyde ethyl hemiacetal reacts with unmodified ketones in the presence of 30-50 each mol % of amines and acids at ambient temperature, affording the corresponding β-hydroxy-β-trifluoromethylated ketones in good yields with good to excellent diastereoselectivities.