Reaction of 2,5-diisopropyl- and 2,5-di-sec-butylpyrazine 1-oxide. Derivatives with phosphoryl chloride and acetic anhydride

In order to examine the α-substitution of side chains, various derivatives of 2,5-diisopropyl- and 2,5-disec-butylpyrazine 1-oxides were subjected to the reaction with phosphoryl chloride and acetic anhydride. Chlorination and acetoxylation were recognized to take place on the pyrazine ring in almost all cases.     

The preparation of polysiloxane–vinyl monomer graft and block copolymers

In another paper the radical polymerization of styrene in the presence of various chlorosilanes was investigated, and polystyrenes having chlorosilyl groups as endgroups were obtained. In the present work attempts were made to obtain polysiloxane styrene graft and block copolymers from chlorosilyl polystyrenes. Block copolymers were obtained with dichlorosilane and graft copolymers with tri- and tetrachlorosilanes. In the latter case the insoluble fractions increased, if a suitable stopper, such as butanol or trimethylchlorosilane [(CH₃)₃SiCl], was not used in the condensation reaction. Methyldichlorosilane was used for the preparation of the graft copolymer, because the Si? H bond was more effective than the Si? Cl bond for the chain transfer reaction.     

Peculiar temperature dependence of the binding of methyl orange and its homologs by 2-diethylaminoethyl methacrylate-N-vinyl-2-pyrrolidone copolymers

2-Diethylaminoethyl methacrylate (DEAEMA)–N-vinyl-2-pyrrolidone (VPy) copolymers of various compositions have been synthesized. The resultant copolymers were examined for their ability to bind methyl orange and its homologs, in particular butyl orange, at 5, 15, 25, and 35°C in aqueous solutions. The amount of binding of butyl orange is much higher with the copolymers than with polyvinylpyrrolidone or with 2-hydroxyethyl methacrylate–N-vinyl-2-pyrrolidone copolymers. Introduction of only 3% of the hydrophobic DEAEMA residue increases markedly the binding affinity toward the cosolute. Maximal binding is obtained at 15°C in the temperature range measured. This peculiar temperature dependence of the extent of binding is explicable on the basis of hydrophobic effects involved in this binding. The peculiar temperature dependence disappeared in aqueous solution of NaSCN which acts as a water-structure breaker: the extent of binding changes regularly with temperature. This is interpretable only in terms of reduction of hydrophobic contribution to the binding. With propyl orange, which is a less hydrophobic cosolute than butyl orange, the peculiarity of the binding was not detected.     

Protein separation by nonsynchronous coil planet centrifuge with aqueous-aqueous polymer phase systems

Counter-current chromatographic separation of proteins was performed using a rotary-seal-free nonsynchronous coil planet centrifuge (CPC) fabricated in our laboratory. This apparatus has a unique feature that allows a freely adjustable rotational rate of the coiled separation column at a given revolution speed. The separation was performed using a set of stable proteins including cytochrome c, myoglobin and lysozyme with two different types of aqueous-aqueous polymer phase systems, i.e., PEG (polyethylene glycol) 1000-dibasic potassium phosphate, and PEG 8000-dextran T500 in 5 mM potassium phosphate buffer. Using a set of multilayer coiled columns prepared from 0.8 mm I.D. PTFE tubing with different volumes (11, 24, 39 ml), the effect of the column capacity on the partition efficiency was investigated under a given set of experimental conditions. Among these experiments, the best separation of proteins was attained using the 39 ml capacity column with a 12.5% (w/w) PEG 1000-12.5% (w/w) dibasic potassium phosphate system at 10 rpm of coil rotation under 800 rpm. With lower phase mobile at 0.2 ml/min in the head-to-tail elution, the resolution between cytochrome c and myoglobin was 1.6 and that between myoglobin and lysozyme, 1.9. With upper phase mobile in the head-to-tail elution, the resolution between lysozyme and myoglobin peaks was 1.5. In these two separations, the stationary phase retention was 35.0 and 33.3%, respectively. Further studies were carried out using a pair of eccentric coil assemblies with 0.8 mm I.D. PTFE tubing at a total capacity of 20 ml. A comparable resolution was obtained using both lower and upper phases as a mobile phase in a head-to-tail elution. The results of our studies demonstrate that the nonsynchronous CPC is useful for protein separation with aqueous-aqueous polymer phase systems.     

The synthesis of benzofuroquinolines. IV. Some halobenzofuro[2,3-B]- and [3,2-C]quinoline derivatives

Some 8- or 9-halobenzofuro[2,3-b]quinolines ( 1a , 8-F, 8-C1, 9-F, 9-Cl) and 9-halobenzofuro[2,3-b]quinoline-11-carboxylic acid ( 1b , F, Cl) were synthesized from 6- or 7-halo-3-(2-methoxyphenyl)-2-oxo-1,2-dihydroquino-line-4-carboxylic acids ( 3 ). And, some 9-halo-11(6H)-benzofuro[2,3-b]quinolinone ( 8 , F, Cl, Br) and 2-halo-6(5H)-benzofuro[3,2-c]quinolinone ( 9 , F, Cl, Br) were synthesized from 6-halo-4-hydroxy-3-(2-methoxyphenyl)-2(1H)-quinolinone ( 7 ), and they were converted to the corresponding chlorohalobenzofuroquinolines ( 1c , 9-F, 9-C1, 9-Br, and 2 , F, Cl, Br).     

Dispersity of stratum corneum in the mixed aqueous solutions of binary mixtures between N,N-dimethyldodecylamine oxide and sodium dodecyl sulfate or two terpenes

Solubilization of cholesterol, differential scanning calorimetric (DSC), nuclear magnetic resonance (NMR) and dynamic light scattering (DLS) measurements were performed in order to reveal the dispersion mechanisms of stratum corneum (SC) into each intact corneocytes in the following systems: (1) in the aqueous mixed solutions of sodium dodecyl sulfate (SDS) and N,N-dimethyldodecylamine oxide (C₁₂DMAO); (2) in the aqueous micellar solutions of C₁₂DMAO containing solubilized α-terpineol (α-T); and (3) in the aqueous micellar solutions of C₁₂DMAO containing solubilized limonene. The intercellular lamellar structure of SC was revealed to be disrupted and/or removed in all these solutions. However, considering the micellar sizes and the interaction among molecules in micelle, the dispersion mechanisms in these three systems were different each other. The three dispersion mechanisms of SC were estimated and discussed on the basis of the results of solubilization, DSC, NMR and DLS, respectively.     

Synthesis and polymerization of optically active N-α-methylbenzylmaleimide

Optically active N-α-methylbenzylmaleimide (MBZMI) was prepared with maleic anhydride and d-(+)-α-methylbenzylamine. The polymerizations of MBZMI were carried out with α,α′-azobisisobutyronitrile (AIBN) and n-butyllithium (n-BuLi) in tetrahydrofuran (THF). The specific rotations of the polymers obtained by AIBN and n-BuLi initiator were +11.1° to +13.0° and ?57.0° to ?89.2°, respectively. The weight-average molecular weights (M_w) for the polymers were between 4200 and 8000. Furthermore, MBZMI was copolymerized with styrene (ST) and methyl methacrylate (MMA) with AIBN in THF at 50°C to obtain optically active copolymers. The monomer reactivity ratios of MBZMI (M₁) with ST (M₂) were obtained as r₁ = 0.027, r₂ = 0.094 in the MBZMI–ST and r₁ = 0.15, r₂ = 1.54 in the MBZMI–MMA system. The Q-e values for MBZMI were Q₁ = 0.78, e₁ = 1.62. All the polymers and copolymers were found to show a weakly negative circular dichroism (CD) peak at about 250 nm and a strongly positive CD peak at about 220 nm.     

Polymerization initiated by an electron donor–acceptor complex. Part I. Polymerization of methyl methacrylate initiated by liquid sulfur dioxide–pyridine complex in the presence of carbon tetrachloride

The polymerization of methyl methacrylate can be initiated by a charge-transfer complex of liquid sulfur dioxide and pyridine in the presence of carbon tetrachloride. The molar ratio of sulfur dioxide and pyridine which participated in the complex was found from a spectrophotometric study to be 2:1. The polymerization proceeds through free-radical intermediates. The overall rate of polymerization is proportional to the square root of the concentration of the complex, and the values of k_p/k_t^1/2 under the various polymerization conditions were satisfactorily consistent with the literature value. For the activation energy of the overall reaction, 8.2 kcal./mole was obtained, and for initiation, 9.7 kcal./mole was evaluated from the values of k_p/k_t^1/2. It was deduced from a kinetic mechanism for the initiation that a primary radical may be produced from the reduction of carbon tetrachloride by an associated complex consisting of liquid sulfur dioxide–pyridine complex and the monomer.     

Synthesis and polymerization of N-[4-N′- (α-methylbenzyl)aminocarbonylphenyl]maleimide

A novel type of optically active N-[4-N′-(α-methylbenzyl)aminocarbonylphenyl]maleimide [(R)-MBCP] was synthesized from maleic anhydride, p-aminobenzoic acid, and (R)-methylbenzylamine. Radical homopolymerization of (R)-MBCP was performed in tetrahydrofuran (THF) at 50 and 70°C for 24 h to give optically active polymers having [α]²⁵_D = -141° and -129°, respectively. Anionic polymerization of (R)-MBCP with n-butyllithium in THF and N,N-dimethylformamide gave an optically active polymer having ?78 to ?81° of [α]²⁵_D. Radical copolymerizations of (R)-MBCP (M₁) were performed with styrene (ST, M₂) and methyl methacrylate (MMA, M₂) in THF at 50°C. The monomer reactivity ratios (r₁, r₂) and the Alfrey-Price Q-e values were determined as follows: r₁ = 0.009, r₂ = 0.091, Q₁ = 1.30, e₁ = 1.87 in the (R)-MBCP-ST; r₁ = 0.27, r₂ = 1.21, Q₁ = 0.93, e₁ = 1.46 in the (R)-MBCP-MMA system. Chiroptical properties of the polymers were also investigated. © 1992 John Wiley & Sons, Inc.     

Tensile strength of boric oxide glass in vacuum and at very low humidities

The tensile strength of a glass fiber of pure boric oxide was measured at low humidities and in vacuum. The strength increased from 60 kg/mm² in a relative humidity (RH) range of 7% to 120 kg/mm² at 0.4% RH, levelling off to 0.02% RH which was the lower limit of humidity in this experiment. At relative humidities higher than 0.4% weathering and stress corrosion were observed, while at relative humidities lower than 0.4%, weathering was not observed but the decrease of the strength with a dynamic loading duration was observed, although the behavior was somewhat different from the typical stress corrosion. The strength measured in vacuum was almost equal to that measured at relative humidities lower than 0.4%, although the data were more scattered. The strength of boric oxide glass was much lower than that of silica glass, even when weathering and stress corrosion were depressed to the extreme. This weakness of boric oxide glass may be attributed to its layer structure.