Asymmetric synthesis of highly substituted beta-nitro alcohols and enantiomerically enriched 4,4,5-trisubstituted oxazolidinones

It is demonstrated that alpha,alpha-disubstituted-alpha-nitroketones are reduced to the corresponding trisubstituted nitro alcohols in good to excellent yield and enantiomeric excess by borane-dimethyl sulfide in the presence of a chiral oxazaborolidine catalyst. Reduction of the nitro alcohols to the corresponding amino alcohols and their subsequent conversion to enantiomerically enriched 4,4,5-trisubstituted oxazoldinones is also reported.     

Synthesis and photo-induced dissolution of polymers bearing imino sulfonate groups

Novel photosensitive polymers were synthesized by the copolymerization of methyl methacrylate and 1,2,3,4-tetrahydro-1-naphthylideneimino p-styrenesulfonate (NISS) and by the ternary polymerization of methyl methacrylate, methacrylic acid, and 9-fluorenylideneiminop-styrene-sulfonate (FISS). NISS and FISS units showed good sensitivity to light of wavelengths below 300 nm and below 366 nm, respectively. Although the polymers were insoluble in aqueous alkaline solutions, on irradiation with UV light they became soluble in aqueous alkaline solutions. A remarkable decrease in molecular weight of the polymers was observed during the photolysis of imino sulfonate groups incorporated into the polymers, which assisted the dissolution of the irradiated polymers.     

Depletion flocculation of latex dispersion in ionic micellar systems

The flocculation behavior of anionic and cationic latex dispersions induced by addition of ionic surfactants with different polarities (SDS and cetyltrimethylammonium bromide (CTAB)) have been evaluated by rheological measurements. It was found that in identical polar surfactant systems with particle surfaces of SDS + anionic lattices and CTAB + cationic lattices, a weak and reversible flocculation has been observed in a limited concentration region of surfactant, which was analyzed as a repletion flocculation induced by the volume-restriction effect of the surfactant micelles. On the other hand, in oppositely charged surfactant systems (SDS + cationic lattices and CTAB + anionic lattices), the particles were flocculated strongly in a low surfactant concentration region, which will be based on the charge neutralization and hydrophobic effects from the adsorbed surfactant molecules. After the particles stabilized by the electrostatic repulsion of adsorbed surfactant layers, the system viscosity shows a weak maximum again in a limited concentration region. This weak maximum was influenced by the shear rate and has a complete reversible character, which means that this weak flocculation will be due to the depletion effect from the free micelles after saturated adsorption.     

Interaction between dyes and polyelectrolytes. XIII. Effect of dye aggregation on the excitation energy transfer between bound dyes

Effect of polyanions on the aggregation of methylene blue (MB) was investigated spectrophotometrically. The following polyanions were used: potassium poly(vinyl sulfate), potassium poly(styrenesulfonate), sodium poly(methacrylate), and sodium poly(acrylate). The state of aggregation was largely dependent on the kind of polyanion and polyanion-MB ratio. MB-photo-sensitized isomerization of cis-p-(phenylazo)phenyltrimethylammonium iodide(cis-PTA) to the transisomer was used advantageously to investigate the effect of dye aggregation on the triplet excitation energy transfer between cationic dyes bound to polyanions. Although the efficiency of the excitation energy transfer between MB and cis-PTA was enhanced by the addition of polyanions, the formation of highly aggregated MB reduced the efficiency of the excitation energy transfer. Correlation with the dye aggregation induced by polyanions and the efficiency of excitation energy transfer between dyes was discussed.     

A convenient stereoselective synthesis of β-lactams from β-hydroxy-α-thioalkylesters prepared from Michael/aldol tandem reaction or stereoselective addition of thiols to the Baylis-Hillman adducts

A convenient stereoselective synthesis of β-lactams from thio-Michael/aldol tandem adduct is described. syn-Selective tandem reaction followed by amidation and intramolecular S_N2 reaction provided β-lactams in diastereomerically pure form. The tandem reaction with aliphatic aldehydes, on the other hand, afforded a mixture of diastereomers of corresponding tandem adducts in about 3:1 ratio so that the conversion to β-lactams afforded a diastereomeric mixture. As an alternative approach to prepare the tandem adducts, the stereoselective Michael addition of aliphatic thiols to Baylis-Hillman adduct was developed. The stereoselectivity was sensitive to the protective group at the hydroxyl group and TBS protection brought the most successful syn-selective formation of the tandem adducts. The procedure could be applied to the ketone derivatives of the Baylis-Hillman adduct but no selectivity was observed for the nitrile-Baylis-Hillman adducts. A similar conversion of the adduct provided desired β-lactams stereoselectively.     

Determination of pheophytinatonickel(II) by reversed-phase highperformance liquid chromatography

Summary HPLC determination of pheophytinatonicke(II) (Pheo-Ni) prepared by the replacement of magnesium(II) in chlorophyll with nicke(II) is described. The good separation of PheoNi was obtained by using chemically bonded C₁₈ as the stationary phase and acetone-methanol (50∶50, vol/vol) as the mobile phase. Conventional spectrophotometric method was also used for the determination of PheoNi. For the synthetic samples prepared by mixing (pheophytinato a) nicke(II) [(Pheo-a) Ni] and (pheophytinato b) nicke(II) [(Pheo-b) Ni], analytical values obtained by the spectrophotometric method were very high compared to those obtained by HPLC. In the proposed HPLC method, (Pheo-a) Ni and (Pheo-b). Ni could be determined in the concentration range of 0.028–30μg/ml and 0.038–30μg/ml with relative standard deviations (n=10) of 3.1% and 0.8%, respectively.     

Amperometric biosensor based on reductive H2O2 detection using pentacyanoferrate-bound polymer for creatinine determination

Pentacyanoferrate-bound poly(1-vinylimidazole) (PVI[Fe(CN)₅]) was selected as a mediator for amperometric creatinine determination based on the reductive H₂O₂ detection. Creatinine amidohydrolase (CNH), creatine amidohydrolase (CRH), sarcosine oxidase (SOD), peroxidase (POD), and PVI[Fe(CN)₅] were crosslinked with poly(ethylene glycol) diglycidyl ether (PEGDGE) on a glassy carbon (GC) electrode for a creatinine biosensor fabrication. Reduction current was monitored at −0.1 V in the presence of creatinine and O₂. It is revealed that PVI[Fe(CN)₅] is suitable as a mediator for a bioelectrocatalytic reaction of POD, since PVI[Fe(CN)₅] neither reacts with reactants nor works as an electron acceptor of SOD. The amounts of PVI[Fe(CN)₅], PEGDGE, and enzymes were optimized toward creatinine detection. Nafion as a protecting film successfully prevented the enzyme layer from interferences. The detection limit and linear range in creatinine determination were 12 μM and 12–500 μM (R² = 0.993), respectively, and the sensitivity was 11 mA cm⁻² M⁻¹, which is applicable for urine creatinine tests. The results of the creatinine determination for four urine samples measured with this proposed method were compared with Jaffe method, and a good correlation was obtained between the results.     

Surface modification for nano‐lignocellulose fiber through vapor‐phase‐assisted surface polymerization

This study addresses the inherent issues surrounding surface modification methods of nanofibers and proposes an environmentally friendly and less toxic strategy for the surface modification of hydrophilic nanofiber. From the continuation of our previous work, which discussed the easy production of nanofiber (average size: 127 nm) from oil palm mesocarp fiber (OPMF), in this work, the surface of nanofibers (M‐IL‐OPMF) were modified through vapor‐phase‐assisted surface polymerization (VASP) to improve the affinity of interface between the polymer grafted M‐IL‐OPMF and non‐polar matrix. VASP of ε‐caprolactone was successfully proceeded from the [M‐IL‐OPMF] at 70 °C for 24 h and 72 h, and compositions were estimated to be 35.7% fiber/64.3% polymer and 27.8% fiber/72.2% polymer. To confirm the grafting of PCL, size‐exclusion chromatography (SEC) and Fourier transform infrared (FT‐IR) spectroscopy, thermogravimetry (TG), and dispersibility test in hydrophobic solvent were carried out. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2575–2580     

Synthesis of Substituted Phenyl Esters of Amino Acids and Polycondensation in Langmuirblodgett Films

Long-alkyl-chain phenyl esters of β-alanine, glycine, and L-valine were prepared, and their monolayer properties were correlated with their molecular structures. These compounds formed stable monolayers on acidic subphases. In particular, the p-hexadecylphenyl esters of β-alanine and glycine were remarkably stable, and their monolayers could be deposited on calcium fluoride plates as Y-type film by Blodgett's technique. The polycondensation of multilayers under an atmosphere saturated with triethylamine was investigated by changes in the IR spectra. It was determined that the polycondensation proceeded by a first-order reaction mechanism in the initial stage and that the rate in multilayers was faster than that in the bulk crystalline powder. These results suggest that the polycondensation is accelerated by a regular arrangement of the monomer in the multilayers, where the active sites are concentrated and located better for the polycondensation. In the case of the polycondensation in multilayers of the glycine ester, two kinds of condensation proceeded to afford poly(glycine) and 2,5-piperazinedione.     

Synthesis of L-Lysine and L-Glutamic Acid Derivatives with Long Alkyl Chains and Polycondensation of Langmuir-Blodgett Films

Two esters of L-lysine and L-glutamic acid containing long alkyl groups were synthesized and their polycondensation in monolayers and multilayers was investigated. The pressure-area isotherms of the ester of L-lysine depend markedly on the time of residence at the air-water interface. The change of FT-IR spectra of the deposited film, which can be lifted as a Z-type film, indicates that polycondensation can occur in the monolayer at 10°C without any treatment. The spectrum of the film cast from chloroform hardly changed with time. These results lead to the conclusion that a regular arrangement of monomer molecules in the monolayer, where the amino and ester carbonyl groups are concentrated, is more suitable for the polycondensation. The ester of L-glutamic acid can also form stable monolayers which can be easily deposited on a hydrophobic plate as a Y-type film by the Blodgett technique. The polycondensation of multilayers under an atmosphere of triethylamine was investigated by IR spectroscopy. It indicates that the condensation in multilayers proceeds via intermolecular and intramolecular reactions, by which poly(L-glutamate) derivatives and 2-pyrrolidone derivatives are formed, respectively. The condensation in the bulk crystalline powder gives exclusively the 2-pyrrolidone derivative by intramolecular reaction. These results suggest that the monomer molecules in the multilayers are favorably aligned for the intermolecular reaction, in contrast to the situation in the bulk crystalline powder.