Showing papers on "Phosphotungstic acid published in 1984"

A Proposed Model of Glycogen Particle

Abstract: The size of glycogen particles was decreased by treatment with trichloroacetic acid (TCA), phosphotungstic acid or hot 30% potassium hydroxide, but was not changed by treatment with 0.1 M or 0.5 M sodium hydroxide. Treatment with 2-mercaptoethanol did not disrupt large glycogen particles. Chymotrypsin, alkaline protease, and β-amylase did not affect the size of glycogen particles. Large glycogen particles were partially split by treatment with a-amylase. A large glycogen particle appears to be composed of several fundamental particles 20 -30 nm in diameter linked by α-1, 4-glucan chains. A model of the glycogen particle was proposed.

Production of cyclic ether

Abstract: PURPOSE: To obtain a cyclic ether such as THF, oxetane, etc. under a relative mild condition, by using a heteropolyacid as a catalyst, and cyclizing an alcohol containing two hydroxyl groups in the molecule or its acetic acid ester. CONSTITUTION: A novel catalyst consisting of a heteropolyacid such as phosphomolybdic acid, phosphotungstic acid or its salts, having low corrosive properties, low deterioration in activity, and stability for a long period, is used, a dihydric alcohol (e.g., 1,3-propanediol, etc.) or a dihydric alcohol acid ester (monoacetic ester, or diacetic acid ester) is reacted and cyclized at 70W250°C, preferably at 100W200°C to give a cyclic ether. The reaction product is readily separated from both the catalyst and a raw material by distillation. COPYRIGHT: (C)1986,JPO&Japio

Cation exchange properties of crown ether-phosphotungstic acid precipitates

Abstract: Precipitate formation between phosphotungstic acid and crown ethers is a general phenomenon, producing solids with selective ion exchange behavior for the alkali metal ions. Distribution coefficients for Li+, Na+, K+, and Cs+ were measured for a series of these precipitates with different crown ethers. The sorption data are more complicated than for the corresponding phosphomolybdates and indicate a variability in the number of exchangeable sites with H+ and M+ concentration. The crown ether used markedly affects the cation selectivity of the phosphotungstate precipitates.

Separation and recovery of heteropolyacid from polyoxytetramethylene glycol

Abstract: PURPOSE: To recover the titled compound in a form reusable without neutralizing the catalyst, economically in high efficiency, by adding a specific (halogenated) hydrocarbon to a polymer having polyoxytetramethylene group, thereby precipitating and separating the heteropolyacid used as a catalyst. CONSTITUTION: A heteropolyacid (e.g. phosphotungstic acid, etc.) used as a polymerization catalyst and existing in a polymer having polyoxy-tetramethylene group in the molecule (e.g. polyoxytetramethylene glycol) or a mixture of the polymer with an organic solvent, is separated from the polymer by adding a solvent or a solvent mixture comprising a 3W15C hydrocarbon (e.g. n-octane) or a 1W15C halogenated hydrocarbon, etc. to the polymer mixture, thereby separating the heteropolyacid or a phase composed mainly of th-e heteropolyacid from the polymer mixture. COPYRIGHT: (C)1986,JPO&Japio

Preparation of tertiary olefin

Abstract: PURPOSE:To prepare a tertiary olefin, keeping the excellent catalytic activity for a long period, without losing the high long-term reactivity and selectivity even at a low temperature, by decomposing a tertiary ether in the presence of steam using a heteropolyacid supported on a neutral or acidic carrier as a catalyst. CONSTITUTION:A hetropolyacid of formula (X is center element such as P, Si, B, etc.; M is legand element such as Mo, W, V, etc.; l is >1; m is 0.1-10; n is 6-18; p is 10-70; q is 0-40), e.g. silicomolybdic acid, phosphotungstic acid, etc. is supported on a neutral or acidic carrier (e.g. silica, alumina, carbon black, etc.) in an amount of 1-70wt%, preferably 5-50wt% to obtain a catalyst. A tertiary ether is made to contact with the catalyst in the presence of steam at 80-350 deg.C, preferably 100-250 deg.C to obtain the objective compound. The amount of steam is preferably 0.5-5mol per 1mol of the raw material.

Production of polyether polyol copolymer

Abstract: PURPOSE: To provide the titled copolymer having a group other than oxytetramethylene group in the molecule, by reacting a polyhydric alcohol with tetrahydrofuran in the presence of a water-coordinated or water-containing heteropolyacid as a catalyst. CONSTITUTION: A heteropolyacid containing or coordinated with ≤15mol of water per 1mol of the acid, and obtained by condensing one or more oxides of Mo, W and V with the oxyacid of P, Si, As, B, etc., wherein the atomic ratio of the former component to the latter component is 2.5W12, e.g. phosphomolybdic acid, phosphotungstic acid, etc. is used as a catalyst. The objective copolymer can be produced by reacting an alcohol having ≥2 hydroxyl groups in one molecule, e.g. ethylene glycol, propylene glycol, etc. with tetrahydrofuran in the presence of the above catalyst, preferably at 0W150°C. COPYRIGHT: (C)1985,JPO&Japio

Fibrillar structure of alpha-elastin methylester complexes with glycoproteins and proteoglycans.

Abstract: α-Elastin methylester forms with proteoglycan subunits and structural glycoproteins water-insoluble complexes which after staining with phosphotungstic acid (pH 7.0), reveal at large magnification bundles of slender smooth fibrils with a diameter from 4 to 5 nm. Similar fibrils can be observed after interaction of α-elastin methylester with chondroitin sulfate, but only if fixation with glutaraldehyde is used prior to staining. Phosphotungstic acid alters the organization of the complexes, in particular those formed with ligands of low molecular weight. The possible biological significance of the interactions studied is discussed.