Hypophosphites


Hypophosphite, see under Phosphinate Ice, see Hydrogen oxide (solid)  [c.274]

Cm ORINE OXYGEN ACIDS AND SALTS - DICm ORINE MONOXIDE, HYPOCm OROUS ACID, AND HYPOCm ORITES] (Vol 5) Barium hypophosphite [14871-79-5]  [c.89]

Sodium hypophosphite monohydrate [10039-56-2]  [c.906]

Reductions. Hydrazine is a very strong reducing agent. In the presence of oxygen and peroxides, it yields primarily nitrogen and water with more or less ammonia and hydrazoic acid [7782-79-8]. Based on standard electrode potentials, hydrazine in alkaline solution is a stronger reductant than sulfite but weaker than hypophosphite in acid solution, it falls between and Ti ( 7).  [c.277]

In electroless deposition, the substrate, prepared in the same manner as in electroplating (qv), is immersed in a solution containing the desired film components (see Electroless plating). The solutions generally used contain soluble nickel salts, hypophosphite, and organic compounds, and plating occurs by a spontaneous reduction of the metal ions by the hypophosphite at the substrate surface, which is presumed to catalyze the oxidation—reduction reaction.  [c.391]

Uses. The principal use for nickel sulfate is as an electrolyte for the metal-finishing appHcation of nickel electroplating (qv). Nickel sulfate also is used as the electrolyte for nickel electrorefining. High purity nickel sulfate is used in electroless plating (qv) (42), where nickel sulfate and a reducing agent, eg, sodium hypophosphite, are brought together in hot water in the presence of the workpiece to be plated (43). Another appHcation for nickel sulfate is as a nickel strike solution, which is used for replacement coatings (qv) or nickel flashing on steel that is to be porcelain-enameled (see Enamels, porcelain and vitreous). Nickel sulfate is also used as an intermediate in the manufacture of other nickel chemicals and as a catalyst intermediate.  [c.10]

However, hydrogen is formed in two side reactions, ie, by the decomposition of some sodium hypophosphite (eq. 2) and by the direct reaction of phosphoms with sodium hydroxide (eq. 3).  [c.317]

Elemental phosphoms reacts with oxidizing acids such as nitric or strong sulfuric. It also reacts with alkali, forming a combination of phosphine, hypophosphite, and phosphite at increasing rates as the pH increases. In reactions related to electric furnace operation, P is not reactive with carbon monoxide over a wide range of temperatures as shown by its compatibiUty in furnace gases. However, at high temperatures over 1000°C, P reacts with steam to generate 2 5 hydrogen (8).  [c.348]

In addition, a small amount of decomposition of hypophosphite by alkaU occurs.  [c.375]

Excess calcium hydroxide is precipitated by usiag carbon dioxide and the calcium carbonate, calcium hydroxide, and calcium phosphite are removed by filtration. The filtered solution is treated with an equivalent amount of sodium sulfate or sodium carbonate to precipitate calcium sulfate or carbonate. Sodium hypophosphite monohydrate [10039-56-2] is recovered upon concentration of the solution. Phosphinic acid is produced from the sodium salt by ion exchange (qv). The acid is sold as a 50 wt %, 30—32 wt %, or 10 wt % solution. The 30—32 wt % solution is sold as USP grade (Table 12) (63). Phosphinic acid and its salts are strong reduciag agents, especially ia alkaline solution (65).  [c.375]

A principal commercial appHcation of the hypophosphites is ia the electroless plating (qv) process. Nickel salts are chemically reduced by hypophosphites to form a smooth adherent nickel plating to protect the iateriors of large vessels and tank cars. The coating, which can be hardened by heat treatment, usually contains 8—10 wt % phosphoms and is highly impervious.  [c.375]

Phosphine is also made as a by-product of the commercial calcium hypophosphite [7789-79-9]. Calcium phosphite [21056-98-4] is also produced.  [c.377]

Phosphides have varying degrees of metaUic, covalent, and ionic characters to the bonding. Strongly electropositive metals, eg, alkaU metals, alkaline-earths, and lanthanides, yield ionic phosphides that react readily with water to generate phosphine. The metal usually remains as hypophosphite or hydroxide. The phosphine generated from hydrolysis of the phosphides is usually contaminated with pyrophoric diphosphine, which renders the evolved gas spontaneously flammable at a high enough concentration.  [c.377]

Important bath constituents in electroless plating are metal ion concentration, catalyst, reducing agent(s), complexing agent(s), and bath stabilizer(s), along with pH adjusters. Important deposition parameters are temperature, pH, metal ion and reducer concentrations, stabilizer concentration, and trace impurities that can catalyze the decomposition of the solution. Typical reducing agents are sodium hypophosphite (for Ni and Co), formaldehyde, hydrazine and sodium borohydride (for Ni and Au).  [c.528]

Electroplating. Cobalt is plated from chloride, sulfate, duoborate, sulfamate, and mixed anionic baths (57). Cobalt alloyed with nickel, tungsten, iron, molybdenum, chromium, zinc, and precious metals are plated from mixed metal baths (58,59). A cobalt phosphoms alloy is commonly plated from electroless baths. Cobalt tungsten and cobalt molybdenum alloys are produced for their excellent high temperature hardness. Magnetic recording materials are produced by electroplating cobalt from sulfamate baths (60) and phosphoms-containing baths or by electroless plating of cobalt from baths containing sodium hypophosphite as the reducing agent. Cobalt is added to nickel electroplating baths to enhance hardness and brightness or for the production of record and compact discs (61).  [c.382]

Modem electroless plating began in 1944 with the rediscovery that hypophosphite could bring about nickel deposition (7,8). Subsequent work led to the first patents on commercially usable electroless nickel solutions. Although these solutions were very useful for coating metals, they could not be used on most plastics because the operating temperature was 90—100°C. The first electroless nickel solution capable of wide use on plastics was introduced in 1966 (9). This solution was usable at room temperature and was extremely stable (see Nickel and nickel alloys).  [c.106]

Of the large number of potential reducing agents, the principal commercial materials ate formaldehyde (qv) [50-0-0] for copper and silver, hypophosphite for nickel and palladium, and organoboron compounds for gold, nickel, palladium, and copper. The latter two reducing agents produce phosphoms- or boron-containing alloys. The detailed theory of electroless plating has been discussed thoroughly in a number of works (3,10,12—16).  [c.106]

Deposition reactions for some reducing agents are given in Table 1 hydrogen is a principal by-product of each reduction. Elemental phosphoms or boron is codeposited with the reduced metal from hypophosphite, borohydride, or organoborane baths (15). Other minor reactions can also occur (18). All of these reductions can be viewed as dehydrogenation reactions (16,19).  [c.107]

Electroless nickel—boron baths use sodium borohydride or dimethylamine borane [74-94-2] in place of sodium hypophosphite (see Boron compounds). The nickel—boron aHoy is brittle, highly stressed, and much more expensive than nickel—phosphoms aHoys. Nickel—boron is mainly used to replace gold in printed circuit board plating.  [c.108]

Other Metal Processes. The only other types of electroless processes commonly used on metals are electroless gold and palladium. These are restricted to specialized uses because of extremely high cost. The properties of these coatings are not significantly different from electroplated coatings. Organoboron, hypophosphite, and other reduciag agents are used ia proprietary baths. Electroless coatings are used where noncontinuous metal base materials make electrolytic coating impossible. Electroless gold baths ia particular have suffered from iastabiUty and short bath life, but newly developed solutions have overcome this problem (31). Typical appHcations iaclude solder mask-coated priated circuit boards, iasertioa tabs, and surface mount devices. New electroless silver and lead processes are available for specialized uses.  [c.109]

Sodium borohydride or dimethylarnine borane have found limited use as reduciag agents because of expense. In addition, bath stabiHty, plating rate, and deposit properties are inferior to those of formaldehyde-reduced baths. The deposit is a copper—boron alloy. Copper—hypophosphite baths have been iavestigated, but these are poorly autocatalytic, and deposit only very thin coatings.  [c.112]

Emerging Printed Circuit Technologies. Much research has been devoted to developing safer, cheaper, and more reHable alternatives to formaldehyde-reduced electroless coppers, and many processes are in the advanced stages of development (45). These include hypophosphite-reduced electroless coppers substitution of conductive graphite coUoids for electroless coppers direct electroplating over catalyzed or catalyzed and sulfide treated substrates and non-noble metal catalysts. Three-dimensional printed circuit boards, usually on engineering quaHty plastics, are becoming more common (see Engineering plastics). High performance boards of novel types continue to be developed with controUed impedance layers ultrathin and narrow copper conductors ceramic substrates high temperature plastic laminates and Invar or Kovar inner layers in place of copper or dielectric.  [c.112]

Nickel—Phosphorus. Interest in electrodeposited nickel—phosphoms came with realization of the benefits of the electroless nickel-plated ahoy. The properties of the ahoys appear to be the same from either process and are related to the phosphoms content (124). Deposits using 2—15% phosphoms and higher can be electroplated lower phosphoms deposits are dull and higher phosphoms deposits are bright. Phosphite ion provides the phosphoms the more expensive hypophosphite used in electroless nickel is not requited. Low (2%) phosphoms deposits, can be obtained simply using phosphoms acid additions to a Watts bath and operating the bath at 0—2 pH with a temperature of 75—95°C and current of 500—4000 A/m. Higher phosphoms alloys requite higher phosphite in solution. To obtain this without making the bath too acidic, part of the nickel content is added as the reaction product of nickel carbonate and phosphoms acid. Some nickel phosphoms ahoy is being electroplated on large shafts that used to be electrolessly plated.  [c.162]

Ammonium hypophosphite [7803-65-8] M 83.0. Crystd from hot EtOH.  [c.393]

Hydrazoic acid Hydrides, volatile Hydrogen cyanide (unstabilized) Hydrogen (low pressure) Hydrogen peroxide (> 35% water) Magnesium peroxide Mercurous azide Methyl acetylene Methyl lactate Nickel hypophosphite Nitriles > ethyl Nitrogen bromide  [c.1027]

Triethylammonium formate is another reducing agent for q, /3-unsaturated carbonyl compounds. Pd on carbon is better catalyst than Pd-phosphine complex, and citral (49) is reduced to citronellal (50) smoothly[55]. However, the trisubstituted butenolide 60 is reduced to the saturated lactone with potassium formate using Pd(OAc)2. Triethylammonium formate is not effective. Enones are also reduced with potassium formate[56]. Sodium hypophosphite (61) is used for the reduction of double bonds catalyzed by Pd on charcoal[57].  [c.520]

Perchloric acid Acetic acid, acetic anhydride, alcohols, antimony compounds, azo pigments, bismuth and its alloys, methanol, carbonaceous materials, carbon tetrachloride, cellulose, dehydrating agents, diethyl ether, glycols and glycolethers, HCl, HI, hypophosphites, ketones, nitric acid, pyridine, steel, sulfoxides, sulfuric acid  [c.1211]

The analysis of ores of germanium is usuaHy done with an emission spectrograph but can be done in the field using the phenylfluorone method (44). Analysis of germanium refinery samples is usuaHy done after fusion of the sample with KOH or NaOH in nickel cmcibles. FoHowing distiHation of the GeCl from HCl solution of the fusion, the Ge can be determined gravimetricaHy, usuaHy by precipitation of GeS2 from acid solution and by ignition to Ge02 titrimetrically, usuaHy by reduction with sodium hypophosphite and titration with KIO solution or spectraHy, using an atomic absorption spectrophotometer. The last procedure is not considered as accurate as either of the first two. ExceHent reviews of the analytical chemistry of germanium have been pubHshed (45,46).  [c.280]

Gold in a medium of ammonium citrate and chelating agents is suitable for electrochemical displacement (130). Eor electroless plating by reduction, a variety of complexing agents for gold have been formulated such as imides (131), amines, thiourea, and citrates (132), and reducing agents such as hypophosphite, hydrazine, borohydrides, amine boranes, and formaldehyde. The process is autocatalytic. The initial formation of metallic gold on the surface accelerates the rate of subsequent reduction. Therefore, preplating with gold, eg, by electrochemical displacement, is beneficial. In the case of nonconducting substrates, the surfaces are first rendered catalytic by applying a small amount of palladium solution which reacts with a layer of predeposited stannous chloride. In some cases other catalytic agents are employed, eg, cobaltous chloride (133). Spray appHcations, in which a gold solution is sprayed onto the substrate simultaneously with a reducing solution, also have been developed.  [c.385]

Electroless Plating. The metaUi2ing process known as electroless plating (qv) is mainly used for deposition of copper on plastics and for nickel—phosphoms aHoy on plastics and metals. A smaller amount of nickel—boron, nickel—copper—phosphoms, paHadium—boron, paHadium—phosphoms, silver, gold, and gold—boron aHoys are deposited. Formaldehyde (qv) is the most common copper reducing agent, giving pure coatings. Sodium hypophosphite is the agent mainly used for electroless nickel. An unusual nickel—phosphoms aHoy or soHd solution is formed. Unlike electroplating, electroless plating can be used on almost any substrate, metallic or nonmetallic. Often electroless plating is used as the first coating to make glass (qv), ceramic, or plastic conductive, foHowed by conventional electrolytic plating (10,31—34).  [c.133]

The remaining 15% of the elemental P is used in P -dependent apphcations which require the element as a direct reactant. The principal products include P2S5, PCl and POCl, 2 5 hypophosphite, with much smaller amounts leading to PH, red P, phosphonates, and various other phosphoms derivatives. Pinal apphcations include flame retardants (qv), lubricant additives, insecticides, herbicides, water treatment, cleaning compounds, plastici2ers, and semiconductors (14).  [c.354]

The reaction proceeds quantitatively and the hydroiodic acid can be removed by repeated distillation at 5.3 kPa (40 mm Hg), leaving pure H2PO2 as the product. Phosphinic acid may also be prepared by the treatment of barium hypophosphite [14871-79-5] with a stoichiometric quantity of sulfuric acid to precipitate barium sulfate.  [c.375]

Commercially, phosphinic acid and its salts are manufactured by treatment of white phosphoms with a boiling slurry of lime. The desired product, calcium phosphinite [7789-79-9], remains ia solution andiasoluble calcium phosphite [21056-98-4] is precipitated. Hydrogen and phosphine are also formed, the latter containing sufficient diphosphine to make it spontaneously flammable. The details of this compHcated reaction, however, are imperfectly understood. Under some conditions, equal amounts of phosphoms appear as phosphine and phosphite, and the volume of the hydrogen Hberated is nearly proportional to the hypophosphite that forms.  [c.375]

Approximately 4500 tons of sodium hypophosphite [7681-53-0] NaH2P02, was produced in 1990. This material is used principally in electroless nickel plating of plastic objects. Of the secondary products made from primary phosphoms compounds, phosphoms oxychloride is manufactured in the largest volume. Phosphoms pentachloride and phosphoms sulfochloride are made from phosphoms trichloride.  [c.383]

These polyaldol—condensation reactions lead to a system of conjugated double bonds that, when the number of bonds is sufficient, can account for absorption at visible wavelengths, ie, yeUow color. However, the color chromophores can also be formed via further reaction of these species, such as continued oxidation, cyclization, etc. Primarily because of the tendency of nylons to yeUow and because of long-term strength loss, antioxidants are commonly used in commercial polymers. The copper haUde system, the combination of a soluble copper(II) salt with sodium or potassium iodide, is probably the most frequendy used antioxidant in polyamides (98). The mechanism for stabilization by copper haUdes has been reviewed and a new function for the metal ion as a peroxide decomposer has been postulated (99), as well as its accepted role as a radical scavenger (100). What is particulady attractive about this mechanism is that it offers an explanation as to why the copper haUde system works so well in polyamides, whereas copper ions promote severe thermooxidation in polyolefins. In polyamides there is always a carbonyl oxygen available to coordinate the copper in a stable, six-membered ring when the hydroperoxide is formed in its most probable position, alpha to the amide nitrogen. In polyolefins, the possibiUty of coordination seldom occurs, and the copper ion is free to act in its usual role as an oxidation catalyst. Other antioxidants are also used in polyamides, eg, phenols, hypophosphites, and phosphites. However, the high processing temperatures, presence of moisture, and the acid—base functionaUty associated with polyamides significantly limit the number and type of stabilizers that can be used in polyamides. For example, most hindered amines, which have been used with great success when combined with other antioxidants for the thermo- and photostabilization of polypropylene, are thermally unstable above 200°C (101), and therefore caimot be used in a melt process for most polyamides.  [c.229]

Hand in hand with this research on finding a suitable carboxyUc acid chemical for cross-linker has been the search for an economical catalyst system. The catalyst found to be most effective for the esterification reaction was sodium hypophosphite (NaH2P02). This material was also costiy and out of range for the textile industry. Because weak bases function as catalyst, a range of bases has been explored, including the sodium salts of acids such as malic acid.  [c.447]

The reductant of equation 3 can also be hypophosphite. Mixed organocarbonyl compounds of Cr(0) and other oxidation states are also possible. These mixed compounds make the preparation of highly unstable chromium hydrides, eg, tricarbonyl(Tj -2,4-cyclopentadien-l-yl)hydrochromium [36495-37-17, C H Cr(CO)2H, possible (25). Equation 2 represents a typical preparation for organ ochromium (I) compounds. The orange—yellow dibenzene chromium (I) cation forms sparingly soluble salts with large anions, eg, B(CgH5).  [c.134]

Electroless Nickel. The first large-scale electroless process was the Kanigen electroless nickel process from General American Transportation Corp. This hot nickel process uses a hypophosphite reducing agent. Properties of electroless nickel deposits vary greatly depending on the reducing agent hydra2ine [302-01-2] gives a practicaHy pure nickel [7440-02-0], the organoboron reducing agents give very hard nickel—boron aHoys and the most widely used hypophosphite deposit a range (from 1—15 wt % P) of nickel—phosphoms aHoys having unique properties. Acidic (pH 4.0—5.5) baths ate preferred, but alkaline (pH 8—10) baths are also used. Operating temperatures are 70—95°C. Typical formulations use sodium hypophosphite [7681-53-0] as the reducing agent, nickel sulfate [7786-81-4] or nickel chloride [7718-54-9], and ammonium or organic salts as buffers. MHd complexing agents such as citrate or glycolate, and trace quantities of proprietary stabili2ers including heavy metals or sulfur compounds, are used. A large number of commercial baths are available (7,26,27).  [c.108]

The market size for electroless nickel solutions is not known with certaiaty. An estimate for 1990 is 1200 t of nickel, of which 85% may be for plating on metals, and 15% for plating on nonconductors. This estimate is based on hypophosphite production, because virtually all hypophosphite is used for electroless nickels. The corresponding market value of the materials used for plating on metals was 35—40 million. Plating of nonconductors is at least 10 times as great ia terms of area plated owiag to the much lower thicknesses used as compared to metal plating.  [c.109]

Pd-C, R0H,.HC02NH4J hydrazine or sodium hypophosphite, 42-91% yield. 2-Benzylaminopyridine and benzyladenine were stable to these reaction conditions. Lower yields occurred because of the water solubility of the product, thus hampering isolation.  [c.365]

Barium hypophosphite (H2O) [14871-79-5] M 285.4. Ppted from aq soln (3mL/g) by adding EtOH.  [c.398]

Pd-C, ROH, HCO2NH4, hydrazine or sodium hypophosphite, 42-91% yield. 2-Benzylaminopyridine and benzyladenine were stable to these reaction conditions. Lower yields occurred because of the water solubility of the product, thus hampering isolation. Cyclohexene can be used as a hydrogen source in the transfer hydrogenation.  [c.579]


See pages that mention the term Hypophosphites : [c.228]    [c.618]    [c.906]    [c.433]    [c.207]    [c.295]    [c.177]    [c.154]   
Chemistry of the elements (1998) -- [ c.513 , c.516 ]