Recent advances in the synthesis of N-alkenyl carbazoles

N-Alkenyl carbazoles are important building blocks of poly(vinylcarbazole), which is used in photosensitive materials, semiconductors, electroluminescent devices, and non-linear optical materials. Recently, a CN bond formation reaction using transition-metal-catalyzed amination and transition-metal-catalyzed vinylation was successfully extended to the synthesis of N-alkenyl carbazoles. In this paper, I discuss recent examples of the synthesis of N-alkenyl carbazoles, including palladium and copper-catalyzed cross-coupling reactions of carbazoles with alkenes/alkenyl halides, and iridium-catalyzed vinylation of carbazole using vinyl acetate.     

Synthesis and some properties of binuclear ruthenocenes bridged by oligoynes: formation of bis(cyclopentadienylidene)cumulene diruthenium complexes in the two-electron oxidation

The monoynes [Rc*C[triple bond]CRc*] and [Rc'C[triple bond]CRc'] were obtained in improved yields using [Mo(CO)6]/2-FC6H5OH as a catalyst in the alkyne metathesis of [Rc*C[triple bond]CMe] and [Rc'C[triple bond]CMe], respectively (Rc = ruthenocenyl, Rc* = 1',2',3',4',5'-pentamethylruthenocenyl, and Rc' = 2',3',4',5'-tetramethylruthenocenyl groups). The diynes [Rc*(C[triple bond]C)2Rc*] and [Rc'(C[triple bond]C)2Rc'] were synthesized by the oxidative coupling of the corresponding terminal ethynes in good yields. The triyne [Rc*(C[triple bond]C)3Rc*] and the tetrayne [Rc*(C[triple bond]C)4Rc*] were prepared by the hetero- and homocoupling of [Rc*C[triple bond]CC[triple bond]CH], which was obtained from the reaction of [Rc*C[triple bond]CCHO] with Li[N2CSiMe3], respectively. Although the oxidation waves did not always exhibit a clear two-electron oxidation process, the oxidation potentials shifted to a lower potential with an increase in the number of methyl substituents on the ruthenocenyl ring, and shifted to a higher potential with the increase in the number of C[triple bond]C units; this result is in contrast to that found in the [Rc(CH=CH)(n)Rc] series. The chemical oxidation of [Rc'C[triple bond]CRc'] yielded a stable two-electron-oxidized species, the structure of which was confirmed by X-ray crystallography to be [Ru2(mu2-eta(6):eta(6)-C5Me4C=CC5Me4)(eta-C5H5)2](BF4)2. Changing the substituents (Rc, Rc*, and Rc') had no effect on the chemical oxidation, but in the case of the Rc' series the Me substituent increased the stability of the two-electron-oxidized species in solution. The diyne [Rc*(C[triple bond]C)2Rc*] and the triyne [Rc*(C[triple bond]C)3Rc*] also gave a similar but unstable two-electron-oxidized species. In acetone or acetonitrile, the two-electron-oxidized species of [Rc*C[triple bond]CRc*] and [Rc*(C[triple bond]C)2Rc*] gradually formed the corresponding bis(fulvene)-type complexes. This implies that the two-electron-oxidized species of [Rc*(C[triple bond]C)(n)Rc*] are destabilized with the increasing n.     

One-dimensional Kalman filter in a robot system for total analysis of solid dosage formulations

A one-dimensional Kalman filter for peak resolution is applied to a totally automated robot system for liquid chromatographic analysis of solid dosage formulations. Sample solutions were prepared from four tablets of clemastine fumarate (1 mg/tablet) and injected automatically at regular, short intervals onto the column by the robot system. The overlapped peaks in the resulting complicated chromatogram were resolved and evaluated quantitatively by the one-dimensional filter. The peak-resolving powers are shown to be reliable by comparison with a multidimensional Kalman filter. The applicability of the whole analytical system with the linear Kalman filter is discussed.     

Synthesis of spiro bis(1,2,3-triazolium) salts as chiral ionic liquids

Unique chiral spiro ionic liquids based on 1,2,3-triazolium salts were synthesized via an intramolecular double Huisgen reaction. The optical resolution of the liquid precursors and subsequent dialkylations leads to chiral spiro triazolium salts on a gram scale.     

Nickel-catalyzed carboxylation of aryl and vinyl chlorides employing carbon dioxide

Nickel-catalyzed carboxylation of aryl and vinyl chlorides employing carbon dioxide has been developed. The reactions proceeded under a CO(2) pressure of 1 atm at room temperature in the presence of nickel catalysts and Mn powder as a reducing agent. Various aryl chlorides could be converted to the corresponding carboxylic acid in good to high yields. Furthermore, vinyl chlorides were successfully carboxylated with CO(2). Mechanistic study suggests that Ni(I) species is involved in the catalytic cycle.     

Visualization of transient interfacial waves induced by spin-up of two immiscible fluid layers

Abstract  

Interfacial waves of two immiscible layers in a spin-up container were investigated using experimental visualization. While the interface near the central part rose up, instability waves propagated in an azimuthal direction on the interface. These waves were mainly caused by Kelvin–Helmholtz instability for the velocity difference between two layers during spin-up, but had complicated transient characteristics owing to the rotation in a closed system. We visualized the structure of the interfacial waves by the use of three types of optical characteristics of the interface. Image processing provided the detailed factors of the interfacial waves that were classified in four life stages from their generation to disappearance. The initial generation process involved many frequency modes due to a large velocity difference, and then a low mode stood out during the growth, and disappeared with an ellipsoidal sloshing mode to achieve the rigid rotation in both layers.     

Electronic structure of (Nd, Ce)2(Ba, Nd)2Cu3Oy

The dependence of T_c on oxygen content was determined for (Nd_0.67Ce_0.33)₂(Ba_0.67Nd_0.33)₂Cu_3.01O_y. It was found that superconduction appears in a range of y=9.10−9.16 and that T_c is enhanced remarkably by the increase of oxygen content. In an oxygen content range where superconduction appeared, the Ce valence was nearly +4 and the Cu valence changed from 2.31 to 2.33. The conductivity was measured in a wide temperature range between T_c and 1200 K as a function of oxygen partial pressure. The high-temperature conductivity increased with increasing oxygen content. It was found that both carrier concentration and mobility are increased with oxygen content. The conduction at low temperatures was semiconductor-like, and increased with increasing oxygen content, where the energy gap E_A-E_V between acceptor level and top of filled band approached zero.     

On generalized energy equality of the Navier-Stokes equations

We show that for every initial dataa εL ²(Ω) there exists a weak solutionu of the Navier-Stokes equations satisfying the generalized energy inequality introduced by Caffarelli-Kohn-Nirenberg forn=3. We also show that if a weak solutionu εL ^s (0,T;L ^q (Ω)) with 2/q + 2/s ≤ 1 and 3/q + 1/s ≤ 1 forn=3, or 2/q + 2/s ≤ 1 andq ≥ 4 forn ≥ 4, thenu satisfies both the generalized and the usual energy equalities. Moreover we show that the generalized energy equality holds only under the local hypothesis thatu εL ^s (ε, T; L ^q (K)) for all compact setsK ⊂ ⊂ Ω and all 0 <ε <T with the same (q, s) as above when 3 ≤n ≤ 10.