Showing papers on "Sodium hypophosphite published in 1993"

Hydrodehalogenation of polychlorinated aromatic halides by hypophosphite with Pd/C catalyst under multiphase conditions

Abstract: Polyhalogenated benzenes in the presence of a Pd/C catalyst with sodium hypophosphite in a multiphase system consisting of a hydrocarbon solvent, concentrated aqueous alkali and a quaternary onium salt undergo reduction with rapid and progressive displacement of all their chlorine atoms. The onium salt, being insoluble in both the organic and the aqueous phases, coats, as a third liquid phase, the Pd/C catalyst. The strong alkaline medium and the phase-transfer agent are synergic. Operating at 50 °C, 1,2,4,5-tetrachlorobenzene gives after 2.5 h a 99% yield of benzene.Enhancement of the reaction rate, compared with already known methods, has been attributed to the transfer of phosphite anion from the aqueous solution to the catalyst surface, to partition of halogenated compounds between the hydrocarbon solution and the liquid phase of the phasetransfer agent and to the rapid removal of HCI adsorbed on Pd/C by the alkaline medium.The reaction is also effective with aryl bromides and deactivated p-methoxyaryl halides.

Infrared spectroscopy studies of the effects of the catalyst on the ester cross-linking of cellulose by poly(carboxylic acids)

Abstract: The esterification of cellulose by a poly(carboxylic acid) proceeds in two steps: the formation of a 5-membered cyclic anhydride intermediate by the dehydration of two carboxyls, and the reaction between cellulose and the anhydride intermediate to form an ester. Sodium hypophosphite is the most effective catalyst for the esterification. The effect of sodium hypophosphite on the esterification of cotton cellulose was studied by Fourier transform infrared spectroscopy (FTIR). It was found that sodium hypophosphite accelerates both the formation of the cyclic anhydride intermediate and the reaction between the anhydride intermediate and cellulose. The chief role of sodium hypophosphite is possibly the acceleration of the esterification of cellulose by the anhydride intermediate. © 1993 John Wiley & Sons, Inc.

Metal-coated colloidal particles

Abstract: Procedures are described for coating of submicrometre ceramic powders with copper and nickel. The process required precoating of the core particles with a palladium catalyst. A precoating procedure was developed in which palladium chloride is reduced by sodium hypophosphite or stannous chloride on the powder surface in aqueous suspensions. Commercial electroless solutions were used to deposit copper and nickel on the catalysed powders. The effect of various experimental parameters on the effectiveness of the surface conditioning of the particles was also investigated.

Spherical amorphous nickel-phosphorus alloy particles with uniform size prepared at room temperature

Abstract: A new chemical method for preparing ultrafine amorphous Ni85P15 alloy particles with uniform size and spherical shape is reported. The particles were prepared by reduction of nickel chloride with sodium hypophosphite initiated with a drop of potassium borohydride solution at room temperature. The preparation mechanism, which consists of primary nucleation of NiB followed by autocatalytic deposition of the components, is discussed. The amorphous structure of the particles was identified by X-ray diffraction and selected area electron diffraction. X-ray photoelectron spectroscopy indicated that nickel and phosphorus are present as an alloy. Transmission election microscopy revealed that the particles are uniform and spherical with a diameter of about 100 nm.

Effects of hypophosphite contents and surface treatment on electroplated Co‐Ni‐P thin films

Abstract: This article describes the effects of sodium hypophosphite (hypo) content in cobalt nickel sulfate bath, and the duration of surface treatment prior to electroplating, on the magnetic, structural, and electrical properties of Co‐Ni‐P thin films. The coercivity of the Co‐Ni‐P layer can be controlled independently either by hypo content or by surface treatment. Transmission electron microscopy microstructure indicates that the width of grain boundaries of Co‐Ni‐P films is influenced by hypo in the magnetic bath. The mechanism of the coercivity increase by hypo in the bath is thought to result from magnetostatic or exchange decoupling at phosphorus‐rich grain boundaries. Effects of these factors on media noise can be well‐explained by the microstructural change of Co‐Ni‐P layers.

Electroless nickel plating from an acidic tartrate bath

Abstract: Nickel-phosphorus coatings have been obtained by electroless plating from acidic solutions containing sodium potassium tartrate and sodium hypophosphite Allylthiourea has been used to stabilize the solution. Boric acid and sodium chloride enhance the plating process. The effect of temperature and pH on the deposition rate has been studied and a suitable rate equation is proposed

Alkali Metal Salts of Hydroxy Acids as Catalysts in Durable Press Finishing with Butanetetracarboxylic Acid

Abstract: Alkali metal salts of hydroxy acids have been investigated as catalysts for esterification cross-linking of cotton with 1,2,3,4-butanetetracarboxylic add to produce cotton fabrics with smooth drying properties. Of the sodium salts of several acids studied, the sodium citrates produce fabrics with the best appearance properties. The sodium citrates serve both as donors of citric acid for cross-linking and of sodium ions for catalysis of the esterification of cotton cellulose by the two polycarboxylic acids. Although the use of citric acid as an extender for the more expensive butanetracarboxylic acid has been reported in non-formaldehyde finishing of cotton fabrics for smooth drying properties the catalyst used was sodium hypophosphite. Comparisons are made between fabrics finished with the phosphorus-containing system and the butanetetracarboxylic acid/sodium citrate systems. Textile properties, fabric whiteness, effect of pad bath pH, and extent of esterification are discussed.

Electroless palladium plating method and electroless plating bath for the same

Abstract: PURPOSE:To provide a electroless palladium plating bath and the electroless plating method partially and selectively plating without necessitating activating a surface or forming a mask. CONSTITUTION:The palladium high speed partial plating is directly executed by using the plating bath containing palladium acetate or palladium chloride as a palladium compound and furthermore sodium hypophosphite and ethylene diamine and irradiating a material to be plated dipped in the plating bath with laser. In the case of using palladium chloride, a thallium compound is preferably added.

Electroless plating method to aluminum material

Abstract: PURPOSE:To develop an Al member having the plating layer excellent in characteristics by forming the metal substituted film consisting essentially of Zn or Sn and subjecting the metal to electroless plating after activating its surface. CONSTITUTION:After cleaning the surface of Al or an Al alloy made member, the member is immersed in the aq. soln. for forming the metal substituted film consisting essentially of Zn or Sn to form the metal substituted film consisting essentially of Zn or Sn on the surface. Then, after uniformly activating the surface by being treated with the aq. soln. containing the reductant such as sodium hypophosphite and having 4-12pH value, the member is immersed in the electroless plating liq. such as electroless Ni plating liq. to form the electroless plating Al metallic member having excellent appearence, adhesiveness, corrosion resistance and covering power, etc.

Soft magnetic material film and manufacture thereof

Abstract: PURPOSE:To provide a soft magnetic material film made of NiFeP having low coercive force and favorable characteristics as a soft magnetic material and a method to uniformly and stably manufacture the film by electroless plating. CONSTITUTION:A soft magnetic material film consisting of NIFeP, characterized in that the Ni content is 70-85 weight% and the value of the Fe/P (weight ratio) is 8-1, is obtained by treating the film in an electroless plating bath consisting of metal ions with nickel and iron as main components, as well as a water solution containing a PH adjusting agent, and containing 0.2-0.5mol/L of ammonium sulfate as a PH buffer 0.5-1mol/L of citrate as a complexing agent for the metal ions, and 0.005-0.03mol/L of sodium hypophosphite as a reducing agent for the metal ions.

Method of making hypophosphorous acid

Abstract: Disclosed is a method of making hypophosphorous acid from sodium hypophosphite by performing electrodialytic water splitting upon an aqueous solution of sodium hypophosphite. The process can be tied into an existing process for producing sodium hypophosphite wherein the product of the sodium hypophosphite process is used as a starting material in the hypophosphorous acid process and the depleted sodium hypophosphite solution from the hypophosphorous acid process, which contains some hypophosphorous acid, is used to adjust the pH in the sodium hypophosphite process.

Cross-linking agent, cross-linking method and cross-linking composition

Abstract: PURPOSE: To obtain a cross-linking agent capable of improving moisture and water resistances and free from the generation of formaldehyde, coloring and yellow discoloration when added to a water-soluble polymer containing a hydroxyl group used as eg a binder by compounding a polycarboxylic acid with a salt of an oxyacid of phosphorus CONSTITUTION: A cross-linking agent is composed of a polycarboxylic acid and a salt of an oxyacid of phosphorus 1, 2, 3, 4-Butanetetracarboxylic acid or (meth)acrylic acid having a viscosity of ≥20cps at 25°C in a 25wt% aqueous solution is used as the polycarboxylic acid The salt of the oxyacid of phosphorus is compounded in the ratio of 5-100wt% to the polycarboxylic acid and especially in the case of the above-mentioned acrylic acid, 10-30wt% Sodium hypophosphite is used as the salt of the oxyacid of phosphorus These cross- linking agent components are compounded in the ratio of 3-20wt% (the polycarboxylic acid) and 5-100wt% (the salt of the oxyacid of phosphorus) to a water-soluble polymer containing a hydroxyl group respectively As the water-soluble polymer, polyvinyl alcohol, etc, are used COPYRIGHT: (C)1995,JPO

Chlorinated polyethylene mixture

Abstract: PURPOSE:To obtain the subject composition improved in heat stability, prevented in coloring of a molded body and useful as a characteristics improver of a large-sized molded product by mixing a chlorinated polyethylene with a phosphorus based reducing agent. CONSTITUTION:The objective composition obtained by mixing (A) 100 pts.wt. chlorinated polyethylene having 15-50wt.%, preferably 20-40wt.% chlorine content with (B) 0.01-5 pts.wt., preferably 0.05-4 pts.wt. phosphorus based reducing agent (e.g. ammonium hypophosphite or sodium hypophosphite). The composition is prepared by e.g. a method by adding the component B to the component A in an aqueous solution in the production process of the component A, method by dry-mixing the powdery component B with powder of the component A using a Henshel mixer, etc., and method melting and kneading the component A with the component B using a kneader, etc. Furthermore, melting, kneading and molding of the composition are preferably carried out at <=220 deg.C.

Palladium powder and production thereof

Abstract: PURPOSE:To obtain a palladium powder having an excellent property for a paste for calcination to make an electrode, a circuit or the like for electronics. CONSTITUTION:The spherical palladium powder having 0.1-1mum of distribution range of primary particle diameter by the SEM observation, 0.1-1.5mum of distribution range of particle size by laser scattering method and =50 deg.C in a presence of a surface active agent with use of a sodium hypophosphite solution.

Electrical Contact Characteristics of Electroless Ni-Pd-P Alloy Films

Abstract: A study was been made on the effect of the addition of palladium chloride on the electrical contact properties of electroless nickel-palladium-phosphorus alloy films obtained using sodium hypophosphite as the reducing agent.The following results were obtained;1) Stable baths were obtained by adding TDG and increasing the pH.2) Film formation was controlled easily by changing the metallic ion of the baths.3) The films were subjected to non-working and working life test (100V-0.5A) and were found to exhibit good electrical contact characteristics.

Hydrodehalogenation of Polychlorinated Aromatic Halides by Hypophosphite with Pd/C Catalyst under Multiphase Conditions.

Abstract: Polyhalogenated benzenes in the presence of a Pd/C catalyst with sodium hypophosphite in a multiphase system consisting of a hydrocarbon solvent, concentrated aqueous alkali and a quaternary onium salt undergo reduction with rapid and progressive displacement of all their chlorine atoms. The onium salt, being insoluble in both the organic and the aqueous phases, coats, as a third liquid phase, the Pd/C catalyst. The strong alkaline medium and the phase-transfer agent are synergic. Operating at 50 °C, 1,2,4,5-tetrachlorobenzene gives after 2.5 h a 99% yield of benzene.Enhancement of the reaction rate, compared with already known methods, has been attributed to the transfer of phosphite anion from the aqueous solution to the catalyst surface, to partition of halogenated compounds between the hydrocarbon solution and the liquid phase of the phasetransfer agent and to the rapid removal of HCI adsorbed on Pd/C by the alkaline medium.The reaction is also effective with aryl bromides and deactivated p-methoxyaryl halides.

Vibrational Spectroscopic Study of Nickel(II) Hypophosphite, Ni(H2PO2) 2.

Abstract: The vibrational spectrum of nickel(II) hypophosphite is reported for the first time. A comparison between the solid-state Raman spectrum and that of a 0.6 M aqueous solution of nickel(II) hypophosphite with sodium hypophosphite indicates the presence of a bidentate monohypophosphito complex, Ni(H 2 PO 2 ) + , and hypophosphite ions H 2 PO − 2 in the solid state, with dissociation into hexa-aquo nickel(II) ions and hypophosphite ions in aqueous solution. This is compared with the behaviour of nickel(II) carboxylates in the solid state and in aqueous solution.

Catalytic Hydrogen‐Transfer Reduction of Polyhalofluoroalkanes Using Sodium Hypophosphite.

Abstract: The catalytic hydrogen-transfer reduction of polyhalofluoroalkanes using sodium hypophosphite in the presence of a platinum or palladium catalyst is described. A selective reduction of carbon-bromine bonds could be performed under mild conditions.