Synthesis of amphiphilic particles in the presence of inert solvents and their application to lipase immobilization

To develop monodisperse amphiphilic polymer particles on which a large amount of lipase could be immobilized, we performed seed polymerizations of glycidyl methacrylate and allyl methacrylate in the presence of nonpolar inert and polar inert solvents. The amphiphilic porous polymer particles, which had both hydrophilic guanidino groups and hydrophobic stearoyl groups, were synthesized in the presence of n‐decane and had a large amount of macropores with diameters of 50–1000 nm. The amount of lipase immobilized on the amphiphilic particles synthesized in the presence of n‐decane was 3.85 times that of the lipase immobilized on the amphiphilic particles synthesized in the absence of a solvent. The immobilized lipase prepared with the amphiphilic particles synthesized in the presence of n‐decane exhibited a high transesterification activity in n‐hexane and could be used repeatedly without a considerable activity loss. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 874–884, 2002; DOI 10.1002/pola.10178     

Thermodynamics of surfactant-dye complex formation in aqueous solutions. Sodium alkyl sulfates and azo oil dye systems

Thermodynamics of surfactant-dye complex formation have been studied, in terms of equilibrium coefficient, using a spectrophotometer. The systems are 6 sodium alkyl sulfates, which have different alkyl chain lengths, and 4-phenylazo-1-naphthylamine. A pronounced spectral change in the dye solution occurs on addition of the surfactant; the change has a definite isosbestic point and a new absorption band at 535 nm because of surfactant-dye complex formation, which is caused by hydrophilic-hydrophilic interaction. As the alkyl chain length in the surfactant increases, the values of free energy change (negative) increase, while the value of enthalpy change (negative) increases and the value of entropy change (positive) decreases. The longer the alkyl chain length in surfactant increase, the more stable the surfactant-dye complex becomes.Surfactant-dye complex will form due to hydrophilic-hydrophilic interaction and will become more stable due to hydrophobic-hydrophobic interaction.     

Cobalt schiff base complex catalysed solvolytic ring opening of epoxy compounds

Co(salen) catalyzes solvolytic ring opening of epoxy compounds in methanol to give glycol monomethyl ether derivatives. Active species is Co(salen) (OH) which is formed in situ, and its catalytic activity depends on the pKa of the conjugated acid of X in Co(salen) (X) (X=OAc, OCH₂CF₃, OH).

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() , . ()(OH), in situ X () (X) ( X=OAc, OCH₂CF₃, OH).

     

Separation of copolymers using high-performance liquid chromatography with polymeric stationary phase and liquefied carbon dioxide as adsorption promoting solvent

Chromatographic separation of copolymers depending on the chemical composition was studied by a solvent gradient method using liquefied carbon dioxide (CO2) as an adsorption promoting solvent. As the high polar stationary phase, non-bonded silica gel, crosslinked acrylamide (AA) gel and crosslinked acrylonitrile (AN) gel were utilized. All columns showed the typical normal phase type of adsorption. Polymeric stationary phases showed the higher sample recovery for styrene-methyl methacrylate (St-MMAs) copolymers, indicating suitability for quantitative analyses. The separations of butyl methacrylate (BMA)-methyl methacrylate, and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (FBMA)-methy methacrylate copolymers were also carried out, and the latter copolymers were separated based on the CO2-philicity with acrylonitrile column.     

Synthesis and characterization of highly fluorescent polythiophene derivatives containing polystyrene sidearms

In this study, macroinitiators with different content of atom‐transfer radical polymerization (ATRP) functional group on polythiophene backbone were first prepared by the copolymerization of 3‐[1‐ethyl‐2‐(2‐bromopropionate)]thiophene and 3‐hexylthiophene with various feed ratio. Then poly [3‐hexyl‐2,5‐thienylene‐co‐3‐[1‐ ethyl‐2‐(2‐[poly(styrene)]propionate)]‐2,5‐thienylene] (PTTBr‐PS) with different graft density were obtained by ATRP of styrene from these macroinitiators in anisole. The degree of polymerization of PS sidearm (DP_PS) was controlled by polymerization time. The structures of obtained graft copolymers were characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (¹H NMR) and differential scanning calorimetry (DSC). Introduction of the PS sidearms onto the backbone of polythiophene was an attempt to trap the polythiophene backbone in a “solution‐like” conformation, thus inhibit the packing of polythiophene backbone and result in the improvement of fluorescent property in solid state. This was verified by the UV–vis and fluorescence analyses. Besides, it was also found that the optical property of PTTBr‐PS graft copolymer was dominated by its graft density and independent on the degree of polymerization of its PS sidearm. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1003–1013, 2008     

A novel direct N-alkenylation of nitrogen-containing heterocycles with magnesium alkylidene carbenoids

Treatment of magnesium alkylidene carbenoids, which were generated from 1-chlorovinyl p-tolyl sulfoxides with isopropylmagnesium chloride at −78 °C in toluene, with N-lithio nitrogen-containing heterocycles (e.g., indole, indazole, phenothiazine, and phenoxazine) gave N-alkenylated products in moderate to good yields. The intermediate of this reaction was found to be the alkenyl anion, which could be trapped with iodoalkanes using CuI as a catalyst to give the heterocycles having fully substituted alkenes on the nitrogen. The alkenyl anion intermediate could be trapped also with benzoyl chloride and phenyl isocyanate. This reaction offers a quite novel and direct N-alkenylation of nitrogen-containing heterocycles.     

Studies on the nematic-isotropic phase transitions in liquid crystals

Compressibility-pressure relations in the region of nematic-isotropic phase transitions under constant temperature were studied, and the value of critical exponent was estimated.     

Study of the energy and charged multiplicity dependence of inclusiveπ− production in π−p interactions up to fermilab energies

Using new data from 100 $\text{GeV}\text{c π}{}^{\mathrm{?}}$ interactions, we find the energy dependence of the invariant cross-section in the target fragmentation (central) region to be consistent with an $\text{A + Bs}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}\text{(C + Ds}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>4</mtext>}}\text{)}$ behavior. The leading particle peak near x = + 1 exhibits a width in x which becomes smaller with increasing energy and an integrated cross section which is approximately energy independent.