Polyphosphoric acid phosphoric acid

ACIDS, INORGANIC Boric acid. Chloro-iridic acid. Hydrobromic acid. Hydrochloric acid. Hydrogen bromide. Hydrogen chloride. Hydrogen fluoride. Hydrogen fluoride-Boron trifluoride. Ion-exchange resins. Nitric acid. Periodic acid. Phosphoric acid. Polyphosphoric acid. Sulfuric acid. 

Alkylation of Aromatics. Aromatic hydrocarbons containing a replaceable hydrogen can be alkylated unless steric effects prevent introduction of the alkyl group (61,78-82). The reaction is called the Friedel-Crafts alkylation, first realized in the presence of aluminum chloride, which is the catalyst still the most frequently used and studied in Friedel-Crafts reactions. In addition, many other acid catalysts are effective (80,82-84). These include other Lewis acids (other aluminum halides, gallium chloride, boron trifluoride, ferric chloride, zinc chloride, stannous and stannic chloride, antimony chloride) and protic acids (hydrogen fluoride, concentrated sulfuric acid, phosphoric acid, polyphosphoric acid, trifluo-romethanesulfonic acid, and alkane- and arenesulfonic acids). 

A number of commercial phosphoms-containing polyols have been made by the reaction of propylene oxide and phosphoric or polyphosphoric acid. Some have seen commercial use but tend to have hydrolytic stabiHty limitations and are relatively low in phosphoms content. BASF s Pluracol 684 is a high functionahty polyol containing 4.5% P, sold for Class 11 rigid foam use. 

The synthesis of 2,4-dihydroxyacetophenone [89-84-9] (21) by acylation reactions of resorcinol has been extensively studied. The reaction is performed using acetic anhydride (104), acetyl chloride (105), or acetic acid (106). The esterification of resorcinol by acetic anhydride followed by the isomerization of the diacetate intermediate has also been described in the presence of zinc chloride (107). Alkylation of resorcinol can be carried out using ethers (108), olefins (109), or alcohols (110). The catalysts which are generally used include sulfuric acid, phosphoric and polyphosphoric acids, acidic resins, or aluminum and iron derivatives. 2-Chlororesorcinol [6201-65-1] (22) is obtained by a sulfonation—chloration—desulfonation technique (111). 1,2,4-Trihydroxybenzene [533-73-3] (23) is obtained by hydroxylation of resorcinol using hydrogen peroxide (112) or peracids (113). 

Phosphoric and polyphosphoric acid esters Perfluorinated anionics Sulfonic acid salts Strong surface tension reducers Good oil in water emulsifiers Soluble in polar organics Resistant to biodegradation High chemical stability Resistant to acid and alkaline hydrolysis... 

It is of interest to note that attachment of a basic side chain on carbon of an isomeric dibenzazepine affords a compound in which anticholinergic activity predominates, elantrine (50). Reaction of anthra-quinone (45) with the Grignard reagent from 3-chloro-N,N-dimethylaminopropane in THF in the cold results in addition to but one of the carbonyl groups to yield hydroxyketone 46. This is then converted to oxime 47 in a straightforward manner. Treatment of that intermediate with a mixture of phosphoric and polyphosphoric acids results in net dehydration of... 

Phosphoric acid (orthophosphoric acid), as well as the different phosphoric acids, can ionize to form corresponding phosphates. When phosphoric acid loses its three hydrogen ions, it becomes the phosphate or orthophosphate ion, P043. Likewise, when the polyphosphoric acids lose their hydrogen ions, the corresponding polyphosphate ion is produced. For example,... 

Pyrophosphoric Acid—Polyphosphoric Acids—Metaphosphoric Acid—Complex Metaphosphoric Acids and their Salts—Properties and Reactions of Ortho-, Meta- and Pyro-phosphates—Common and Distinctive Reactions—Estimation of the Phosphoric Acids—Phosphorus m Alloys—Perphosphoric Acids. 

A munber of nitrogen derivatives of phosphoric and polyphosphoric acid (ammonium polyphosphate, melamine pyrophosphate) are used for improving the flame retardance of polyurethanes and other polymers. In thermal decomposition these compounds produce ammonia and the corresponding phosphoric acids which catalyze dehydration and other reactions, causing polymer dehydration during combustion. The coke produced in this process is more or less foamed. Ammonium polyphosphate and melamine pyrophosphate are added to compositions of intumes-cent coatings used for fire protection of various structural elements in construction... 

Ethers are cleaved by HI faster than by HBr and HCl (Scheme 25). To prevent the undesirable reducing action of the reagent, KI and phosphoric or polyphosphoric acid are used to generate HI in situ (equation 32). The ether nd is also cleaved by trimethylsilyl iodide (equation 33). ... 

Cyclization Aluminum chloride. Phosphoric-Formic acid. Polyphosphoric acid. Sodium aluminum chloride. Sodium bistrimethylsilylamide. Stannic chloride. 

Hydrolysis Cupric sulfate. Hydrobromic acid. Ion-exchange resins. Magnesium sulfate. Morpholine. Nitrosyl chloride. Phosphoric-Acetic acid. Polyphosphoric acid. Potassium r-butoxide. Potassium persulfate. Pyruvic acid (by exchange). Rochelle salt. Silver trifluoro-acetate (gem-dihromides). 

Phosphoric and Polyphosphoric Acid Esters, R(OC2H4)xOP(0)(0 M+)2 and [R(OC2H4)xO]2P(0)0 M+ Mainly phosphated POE alcohols and phenols, some sodium alkyl phosphates (not oxyethylenated). The POE materials are available in free acid form or as sodium or amine salts. Products are mixtures of monobasic and dibasic phosphates. 

A number of protic acids have been used to catalyze acylation reactions. It is assumed that the reactions involve the generation of acylium ions. Polymeric reagents such as Nafion-H have been used for example 2-fluorobenzoyl chloride and toluene give the benzophenone derivatives with an ortho.para ratio of 4 81. ° A zeolite-catalyzed acylation (equation 6) has been reported to afford 4-dodecenoyltol-uene in 96% yield but the yields are low with short chain carboxylic acids. Early examples of the use of trifluoroacetic and perchloric acids reported good yields of products. Some more recent examples are shown in equations (7) to (9). Phosphoric and polyphosphoric acids have been used together with carboxylic acids (equation 10),anhydrides and acylureas (equation 11). °... 

Hame retardants that contain phosphorous release polyphosphoric acid and are effective in the condensed phase. These agents form a protective layer. The polyphosphoric acid also splits water out of organic plastics, resulting in formatiOTi of an additional protective carbon layer. 

Some phosphorus compounds decompose in the condensed phase to form phosphoric or polyphosphoric acids. These can act as dehydration catalysts, reacting with cellulosics for example, to form a good char. Char yield is also increased with rigid polyurethanes. The polyphosphoric acid can also form a viscous molten surface layer or surface glass. This layer can shield the polymeric substrate from the flame (heat) and oxygen. Intumescence, which requires an acid such as phosphoric acid, results in a dense carbon char on the polymer surface protecting the substrate from heat and oxygen. 

In the first step, the alcohol, phosphation reagent, and water (or its equivalent in phosphoric or polyphosphoric acid, calculated as a composite of phosphoric anhydride and water) are combined in accord with the following equation ... 

A patent review [4] showed that early intumescent formulations incorporated in polymers contained a precursor of phosphoric or polyphosphoric acid, a pentaerythritol type char source, and melamine, as typical formulations of intumescent coatings. Further developments tried to reduce the complexity of the additive system, for example by using a binary combination of the add precursor with nitrogen-containing compounds, which also act as a char source. While the add source is generally APP, typical examples of the second component are produds of condensation of formaldehyde with substituted ureas products of readions between aromatic diisocyanates and pentaerythritol or melamine polymers containing the piperazine ring in the main chain, also combined with substituted s-triazine, hydroxyalkyl isocyanurate etc. 

At equihbrium, the specific composition of a concentrated phosphoric acid is a function of its P2 s content. Phosphoric acid solutions up to a concentration equivalent of about 94% H PO (68% P2O5) contain H PO as the only phosphoric acid species present. At higher concentrations, the orthophosphoric acid undergoes condensation (polymerization by dehydration) to yield a mixture of phosphoric acid species (Table 5), often referred to genericaHy as polyphosphoric or superphosphoric acid, H20/P20 = - 3, or ultraphosphoric acid, H20/P20 = - 1. At the theoretical P2O5 concentration for orthophosphoric acid of 72.4%, the solution is actually a mixture containing 13% pyrophosphoric acid and about 1% free water. Because the pyrophosphoric acid present is the result of an equihbrium state dependent on the P2 5 content of the solution, pure orthophosphoric acid can be obtained because of a shift in equihbrium back to H PO upon crystallization. 

Commercial condensed phosphoric acids are mixtures of linear polyphosphoric acids made by the thermal process either direcdy or as a by-product of heat recovery. Wet-process acid may also be concentrated to - 70% P2O5 by evaporation. Liaear phosphoric acids are strongly hygroscopic and undergo viscosity changes and hydrolysis to less complex forms when exposed to moist air. Upon dissolution ia excess water, hydrolytic degradation to phosphoric acid occurs the hydrolysis rate is highly temperature-dependent. At 25°C, the half-life for the formation of phosphoric acid from the condensed forms is several days, whereas at 100°C the half-life is a matter of minutes. 

Pyrophosphoric (diphosphoric) acid, H4P2O2, is the only condensed phosphoric acid definitely obtainable ia crystalline form. It has a theoretical P2O5 content of 79.8%. However, Hquid polyphosphoric acid of such content shows by analysis only 42.5% the remainder is phosphoric acid and... 

Condensed Phosphoric Acid. The largest use of polyphosphoric (superphosphoric) acid is as an intermediate in the production of high quahty Hquid fertilizers. The TVA pioneered the development of electric-furnace superphosphoric acid for this appHcation. However, wet-process superphosphoric acid prepared by evaporation of water from wet-process phosphoric acid has almost completely replaced furnace-grade acid in fertilizer manufacture. 

Polyphosphoric acid supported on diatomaceous earth (p. 342) is a petrochemicals catalyst for the polymerization, alkylation, dehydrogenation, and low-temperature isomerization of hydrocarbons. Phosphoric acid is also used in the production of activated carbon (p. 274). In addition to its massive use in the fertilizer industry (p. 524) free phosphoric acid can be used as a stabilizer for clay soils small additions of H3PO4 under moist conditions gradually leach out A1 and Fe from the clay and these form polymeric phosphates which bind the clay particles together. An allied though more refined use is in the setting of dental cements. 

In 1909, Robinson demonstrated the utility of acylamidoketones as intermediates to aryl-and benzyl-substituted 1,3-oxazoles through cyclization with sulfuric acid. Extension of sulfuric acid cyclization conditions to alkyl-substituted oxazoles can give low yields, for example 10-15% for 2,5-dimethyl-l,3-oxazole. Wiegand and Rathbum found that polyphosphoric acid can provide alkyl-substituted oxazoles 4 in yields equal to or greater than those obtained with sulfuric acid. Significantly better yields are seen in the preparation of aryl- and heteroaryl-substituted oxazoles. For example, reaction of ketoamides 5 with 98% phosphoric acid in acetic anhydride gives oxazoles 6 in 90-95% yield. ... 

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