Phosphate salts

If triphenylmethyl chloride in ether is treated with sodium, a yellow colour is produced due to the presence of the anionic spiecies PhsC". Alternatively, if triphenylmethyl chloride is treated with silver perchlorate in a solvent such as THF, the triphenylmethyl cation is obtained. More conveniently, triphenylmethyl salts, PhsC X", can be obtained as orange-red crystalline solids from the action of the appropriate strong acid on triphenylcarbinol in ethanoic or propanoic anhydride solution. The perchlorate, fluoroborate and hexafluoro-phosphate salts are most commonly used for hydride ion abstraction from organic compounds (e.g. cycloheptatriene gives tropylium salts). The salts are rather easily hydrolysed to triphenylcarbinol. 

Manufacture. Phosphoric acid, H PO, is the second largest volume mineral acid produced sulfuric acid is the first. The greatest consumption of phosphoric acid is in the manufacture of phosphate salts, as opposed to direct use as acid. Markets are differentiated according to the purity of the acid. Phosphoric acid is produced commercially by either the wet process or the thermal (furnace) process. Thermal acid, manufactured from elemental... 

The purified acid is recovered from the loaded organic stream by contacting with water in another countercurrent extraction step. In place of water, an aqueous alkafl can be used to recover a purified phosphate salt solution. A small portion of the purified acid is typically used in a backwashing operation to contact the loaded organic phase and to improve the purity of the extract phase prior to recovery of the purified acid. Depending on the miscibility of the solvent with the acid, the purified acid and the raffinate may be stripped of residual solvent which is recycled to the extraction loop. The purified acid can be treated for removal of residual organic impurities, stripped of fluoride to low (10 ppm) levels, and concentrated to the desired P2 s Many variations of this basic scheme have been developed to improve the extraction of phosphate and rejection of impurities to the raffinate stream, and numerous patents have been granted on solvent extraction processes. 

Orthophosphate salts are generally prepared by the partial or total neutralization of orthophosphoric acid. Phase equiUbrium diagrams are particularly usehil in identifying conditions for the preparation of particular phosphate salts. The solution properties of orthophosphate salts of monovalent cations are distincdy different from those of the polyvalent cations, the latter exhibiting incongment solubiUty in most cases. The commercial phosphates include alkah metal, alkaline-earth, heavy metal, mixed metal, and ammonium salts of phosphoric acid. Sodium phosphates are the most important, followed by calcium, ammonium, and potassium salts. 

Potassium Phosphates. The K2O—P20 —H2O system parallels the sodium system in many respects. In addition to the three simple phosphate salts obtained by successive replacement of the protons of phosphoric acid by potassium ions, the system contains a number of crystalline hydrates and double salts (Table 7). Monopotassium phosphate (MKP), known only as the anhydrous salt, is the least soluble of the potassium orthophosphates. Monopotassium phosphate has been studied extensively owing to its piezoelectric and ferroelectric properties (see Ferroelectrics). At ordinary temperatures, KH2PO4 is so far above its Curie point as to give piezoelectric effects in which the emf is proportional to the distorting force. There is virtually no hysteresis. 

Zinc phosphate, Zn2(P0 2> forms the basis of a group of dental cements. Chromium and zinc phosphates are utilized in some metal-treating appHcations to provide corrosion protection and improved paint adhesion. Cobalt(II) phosphate octahydrate [10294-50-5] Co2(P0 2 8H20, is a lavender-colored substance used as a pigment in certain paints and ceramics. Copper phosphates exhibit bioactivity and are used as insecticides and fungicides. Zinc, lead, and silver phosphates are utilized in the production of specialty glasses. The phosphate salts of heavy metals such as Pb, Cr, and Cu, are extremely water insoluble. 

The general manufacturing scheme for phosphate salts is shown in Figure 11. Condensed phosphates are prepared from the appropriate orthophosphate or mixture of orthophosphates, so the preparation of orthophosphates must be considered first for the manufacture of any phosphate salt. Phosphoric acid is neutralized to form a solution or slurry with a carefully adjusted acid/base ratio according to the desired orthophosphate product. The orthophosphate may be recovered either by crystallization from solution, or the entire solution or slurry may be evaporated to dryness. The dewatering (qv) method is determined by the solubihty properties of the product and by its desired physical properties such as crystal size and shape, bulk density, and surface area. Acid orthophosphate salts may be converted to condensed phosphates by thermal dehydration (calcination). 

Alkali Meta.IPhospha.tes, A significant proportion of the phosphoric acid consumed in the manufacture of industrial, food, and pharmaceutical phosphates in the United States is used for the production of sodium salts. Alkali metal orthophosphates generally exhibit congment solubility and are therefore usually manufactured by either crystallisation from solution or drying of the entire reaction mass. Alkaline-earth and other phosphate salts of polyvalent cations typically exhibit incongment solubility and are prepared either by precipitation from solution having a metal oxide/P20 ratio considerably lower than that of the product, or by drying a solution or slurry with the proper metal oxide/P20 ratio. 

Potassium Phosphates. Potassium phosphate salts are analogous to the sodium salts and share many of the same functional properties. The higher cost of potassium hydroxide has restricted these salts to appHcations where high solubiUty or nutrient value is important. Potassium salts are manufactured like their sodium analogues, often on the same equipment. Many of the potassium phosphates are more deflquescent than their sodium analogues and may require special storage and moistureproof containers. 

Table 12. U.S. Consumption of Industrial-Grade Phosphoric Acid and Phosphate Salts in 1989 ...

Inorganic phosphates present htde ha2ard to humans and are mineral nutrients essential to life processes. Attention must be given to the acidity of phosphoric acid, the alkalinity of the bases with which it reacts and the heat released upon neutralization. Appropriate protective gear should be worn when in close contact. Some phosphate salts are reasonably acidic or basic. 

Silver Phosphates. Silver phosphate [7784-09-0], or silver orthophosphate, Ag3P04, is a bright yellow material formed by treating silver nitrate with a soluble phosphate salt or phosphoric acid. Silver pyrophosphate [13465-97-9], is a white salt prepared by the addition of a soluble... 

Oil Repellent. Fluorochemicals are the only class of material that can provide oil repeUency without altering the porosity of the paper or paperboard. Physical barriers to oil penetration are used primarily for their moisture- or gas-barrier properties, with retarded oil penetration as a secondary benefit. The most common od-repeUent additives are long-chain perfluoroalkyl phosphate salts of ammonia or diethanol amine. Commercial sources include Scotchban (3M), Zonyl (DuPont), and Lodyne (Ciba Specialties). There are also a fluorochemical carboxylate salt, Lodyne (Ciba Specialties), and fluorochemical copolymers, eg, Scotchban (3M). The widest range of oily fluid holdout is provided by the fluorochemical copolymers. 

Iron pentacarbonyl and l-methoxy-l,4-cyclohexadiene react as shown by Birch and oo-workera, but in dibutyl ether this solvent has been found superior. The tricarbonyl(methoxy-l,3-cyclohexadiene)iron isomers undergo hydride abstraction with triphenylmethyl tetrafluoro-borate to form the dienyl salt mixture of which the 1-methoxy isomer is hydrolyzed by water to the cyclohexadienone complex. The 2-methoxy isomer can be recovered by precipitation as the hexafluoro-phosphate salt. By this method the 3-methyl-substituted dienone complex has also been prepared from l-methoxy-3-methylbenzene. The use of the conjugated 1-methoxy-1,3-cyclohexadiene in Part B led to no increase in yield or rate and resulted chiefly in another product of higher molecular weight. An alternative procedure for the dienone is to react tricarbonyl(l,4-dimethoxycyclohexadiene)iron with sulfuric acid. ... 

Alkalinity An expression of the total basic anions (hydroxyl groups) present in a solution. It also represents, particularly in water analysis, the bicarbonate, carbonate, and occasionally, the borate, silicate, and phosphate salts which will react with water to produce the hydroxyl groups. 

Phosphaies are used in an astonishing variety of donicsiic and industrial applications but their ubiquitous presence and their substantial impact on everyday life is frequently overlo(4ted. It will be convenient first lo indicate the specihc uses of individual compounds and the properties on which ihey are based, then to conclude with a brief summary of many diffcreni types of application and their interrelation. TTie most widely used compounds are the various phosphate salts of Na, K. NH4 and Ca. TTie uses of di-. iri- and poly-phosphaie.s are mentioned on pp. 527-29. 

Urinary pH. The solubility of phosphate salts increases at lower pH values, while pH scarcely affects the solubility of Ca(C204) over a pH range of 5.7 to 7.5. Bacteria that metabolize urea contribute to an alkaline medium, thus decreasing the solubility of phosphates. 

Write the formula for the phosphate salt (if the complex ion is a cation) or the aluminum salt (if the complex ion is an anion) for the ions in Question 5. 

Hydrolysis 10 mmol of the phosphate salt are dissolved by swirling with Dowex AG50W-X8 (H ) in 200 mL of water. After filtration, the pH is adjusted to 6.0, acid phosphatase (150 U EC 3.1.3.2) is added and the mixture is incubated at 25 CC until complete conversion, as monitored by TLC (48 h). The solution is desalted by ion exchange, concentrated in vacuo, and the residue is crystallized from ethanol to give colorless crystals of D-sorbosc yield 1.6g (89%). 

Phosphate salts formed in the boiler section include ... 

Congruent phosphate programs are modifications of coordinated phosphate programs that operate at a Na P04 ratio lower than the normal 2.8 or 2.85 1. Experience has demonstrated that (contrary to theory) diminished phosphate salt solubility (phosphate hideout) takes place under high-load conditions. This is in addition to the recognized problems of high-temperature crystallization of TSP at the higher ratio of 3 1 (with the formation of some DSP and free caustic). 

The development of monoalkyl phosphate as a low-skin-irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste- and liquid-type skin cleansers, and also on phosphorylation reactions from the viewpoint of industrial production [26]. The preparation and industrial applications of phosphate esters as anionic surfactants were discussed [27]. 

---