Hydrogen Transfer Polymerization Mechanism of Acrylamide Induced by Propagating Polyacrolein Anion

In order to investigate the interaction between acrolein (AL) and acrylamide (AAm) on anionic copolymerization, the homopolymer-izabilities of AL in the presence of several p-substituted phenyl-acetamides such as p-nitroacetanilide, p-chloroacetanilide, acet-anilide, and p-methylacetanilide were investigated in tetrahydro-furan at 0°C using imidazole as an anionic catalyst. A linear co-relation was obtained by Hammett′ s equation as described by log R /R = 0.28σ. This result suggests that the homopolymeriz- P Po ability of AL is influenced by the structure of the amide compound. An increase of the additive propionamide (PAm) on the homopolym-erization of AL induced by the pyridine-water initiation system increased the polymerization rate R; however, it decreased the intrinsic viscosity [η] of poly-AL. From the measurement of infrared spectroscopy and elementary analysis, the presence of a chain transfer reaction between the poly-AL anion and PAm was found. These results support the presence of interaction between AL and AAm derivatives in the copolymerization system.     

Two polymorphs of N1,N4‐bis(5‐hydroxypenta‐1,3‐diynyl)‐N1,N4‐diphenylbenzene‐1,4‐diamine

The title compound, C₂₈H₂₀N₂O₂, forms two conformational polymorphs, (I) and (II), where the molecular structures are similar except for the orientation of the two hydroxy groups. In (I), which was obtained by slow evaporation from chloroform, the two hydroxy groups have an anti conformation. The molecules form a sheet structure within the ac plane, where the hydroxy groups form zigzag hydrogen bonds. In (II), which was obtained by slow evaporation from acetonitrile, the two hydroxy groups have a syn conformation. The molecules form a double‐sheet structure within the ab plane, where the hydroxy groups form 4‐helix hydrogen bonds.     

Total Synthesis of (+)-Sch 725680: Inhibitor of Mammalian A-, B-, and Y-Family DNA Polymerases

The total synthesis of (+)-Sch 725680, a member of the hydrogenated azaphilone family, has been accomplished. The synthesis confirmed the absolute configuration and biological activities of the natural product. A key reaction to construct a hydrogenated azaphilone core skeleton is a Ti-mediated aldol reaction.     

Dynamics of photo-induced terahertz optical activity in metal chiral gratings

We investigated the dynamics of photo-induced optical activity of metal chiral gratings on an Si substrate for terahertz (THz) waves. We employed a new technique that enables optical-pump and THz-probe measurements via broadband THz spectroscopy at the microsecond time scale using a low-repetition-rate pump and a high-repetition-rate probe. We revealed that the THz optical activity decays as a result of the carrier diffusion effect because this optical activity is because of the presence of three-dimensional chiral structures of photo-carriers in the Si substrate.     

Additive effect of polyacrylamide on the anionic polymerization of acrolein

The anionic polymerizations of acrolein (AL) in the presence of polyacrylamide (poly-AAm) induced by imidazole (Im), pyridine (Py)–water, and sodium hydorxide as the anionic initiator were carried out kinetically in an ethanol-water mixture at 0°C. The rate of polymerization R_p in the presence of poly-AAm increased markedly in the Im and Py-water systems, whereas the polymerizability of AL is little changed in the potassium persulfate and silver nitrate (redox systems). These results suggest and the interaction between the amide groups in poly-AAm, the initiator, and the AL monomer is intramolecular. It also indicates the presence of interaction between the carbonyl group of the amide compound and the group of Im. On the other hand, the chemical shifts of the proton of Im in the presence of several amide compounds such as acetamide, propionamide, and N,N-dimethylacetamide were observed in CDCl₃ by nuclear magnetic resonance (NMR) spectroscopy. These results were discussed by assuming a conformational change in poly-AAm in the ethanol–water mixture.     

A generalized stochastic liouville equation. Non-Markovian versus memoryless master equations

The interrelation between the well-known non-Markovian master equation and the new memoryless one used in the previous paper is clarified on the basis of damping theory. The latter equation is generalized to include cases in which the Hamiltonian or the Liouvillian is a random function of time, and is written in a form feasible for perturbational analysis. Thus, the existing stochastic theory in which those cases mentioned above are discussed is equipped with a more tractable basic equation. Two problems discussed in the previous paper, i.e., the random frequency modulation of a quantal oscillator and the Brownian motion of a spin, are treated from the viewpoint of the stochastic theory without such explicit consideration of external reservoirs as was taken in the previous paper.     

Aqueous two-phase extraction of nickel dimethylglyoximato complex and its application to spectrophotometric determination of nickel in stainless steel

A polyethylene glycol (PEG)-based aqueous two-phase system has been established for the extraction of Ni-dimethylglyoximato complex. Appropriate amounts of PEG solution and solid (NH₄)₂SO₄ were added to the Ni-dimethylglyoximato complex which had been formed in the presence of sodium tartrate and K₂S₂O₈ at pH 12 in a separatory funnel and shaken vigorously for about 1 min. The mixture was allowed to stand for 10 min and then the absorbance of the extracted complex in the upper PEG-rich phase was measured at 470 nm. Beer's law was obeyed over the range of 0.26-2.1 ppm Ni. The proposed extraction method has been applied to the determination of Ni in steel. A steel sample was decomposed with an appropriate acid mixture. An aliquot of the sample solution was taken, treated with H₃PO₄ and most of the iron and copper were removed by hydroxide precipitation using solid BaCO₃ to control the pH of the sample solution in advance of the extraction of Ni. The analytical results obtained for Ni in steel certified reference material JSS 650-10 (The Japan Iron and Steel Federation), BCS 323 (Bureau of Analysed Samples Ltd.) and NIST SRM 361 and 362 (National Institute of Standards and Technology) were in good agreement with certified values.     

Development of chiral stationary phases consisting of low-molecular-weight cellulose derivatives covalently bonded to silica gel

We prepared chiral supports whose chiral stationary phase (CSP), consisting of a low-molecular-weight cellulose derivative (degree ofpolymerization: 15), is covalently bonded to silica gel. The cellulose used asthe base material of the CSP was pre-hydrolysed with phosphoric acid before thecoupling reaction to unite a reducing terminal in the cellulose and anaminopropyl group on the surface of silanized silica. After substitutinghydroxyl groups in cellulose by using 3,5-dichlorophenyl isocyanate or phenylisocyanate, we tested the CSP thus obtained for its performance in chiralrecognition and found a wide range of chiral discrimination ability. We alsoconfirmed that an elution using strong solvents as a mobile phasecould be achieved, which is difficult for the coated-type CSPs because themobile phase may dissolve the CSP. However, more enantiomeric mixtures showedlarger selectivity factors () when eluted on the coated-type CSPs thanonthe covalently bonded CSPs. A coated-type CSP consisting of thelow-molecular-weight cellulose phenylcarbamate, prepared as a control CSPsample, showed comparable performance with the commercial coated-type column(CHIRALCEL® OC), so the slightly poorer performance ofthe chemically bonded CSPs may be explained by the difficulty of the polymerconsisting of the CSPs in taking an optimal supermolecular structure requiredfor chiral recognition due to the fixation to the silica gel. The lowdegreeof polymerization may have an additional effect.     

Polymerization of acrolein and methyl vinyl ketone induced by amine–water and pyridine–phenol systems

It was reported that acrolein (AL) in tetrahydrofuran (THF) polymerizes at temperatures below 0°C in the presence of pyridine (Py) and water. To clarify this polymerization mechanism the polymerization of AL and methyl vinyl ketone (MVK) by an initiation system such as Py–water, triethylamine (Et₃N)–water, or Py–phenol(Ph) was carried out. The polymerization rate (R_p) of MVK in the Et₃N–water system was expressed by the same equation, R_p = k [Et₃N] [H₂O] [MVK]², used for AL in the Py–water system. Meanwhile, β-hydroxypropionaldehyde, β-phenoxypropionaldehyde, γ-ketobutanol, and β-phenoxy-1-methylpropionketone were obtained as the initial addition products. The polymer of AL obtained was composed of polymer units of vinyl and aldehyde polymerization, but the structure of MVK polymer obtained by the Py–water system was composed of only vinyl polymerization units. The polymerization of MVK by the Py–Ph system did not occur, however. These results were discussed in terms of the initiation and propagation mechanisms.