The percent concentration of acid is frequently given as a percentage of P2O5, e.g., 75% phosphoric acid contains 54% P2O5, 58% phosphoric acid contains 42% P2O5.
Phosphorus pentoxide, formula P2O5, absorbs moisture to form phosphoric acid H3PO4.
Viscosity: At ambient temperatures, viscosity varies from thin at the 50 and 75% strengths to a syrupy liquid at the 85% strength, to crystals at 100% phosphoric acid.
The unique thermal process developed by Febex allows a reduction of the impurity content to a concentration on the level of the ppb. Combustion of phosphorus is the first phase of the process. Depending on the desired quality, several purification steps follow, enabling the elimination of impurities according to the specific requests of our customers. One of these steps eliminates Arsenic, a critical element for most industries. The concentration of the solution is then adjusted to the desired level. A crystallization step generates a 99% phosphoric acid in crystal form.
Febex’s industrial and analytical equipment enables us to produce phosphoric acid according to individual specifications, conformity guaranteed.
The electronics phosphoric acid is then conditioned in a clean room. This excludes all forms of contamination and guarantees the level of particles during filling. The Certificate of Analysis is issued based on tests performed on a sample collected just before conditioning.
AB - A simple method of wide scope for the synthesis of substituted indolium, quinolinium, isoquinolinium, and benzoazepinium salts has been developed from readily available starting materials. Quaternary ammonium compounds possessing a β-alkenyl substituent and an arylmethyl group readily cyclized in the presence of 115% polyphosphoric acid (PPA) at 300°C for 1 h to furnish the substituted isoquinolinium and benzoazepinium salts in respectable yields (55-67%). On the other hand, alkenylanilinium salts cyclized at 130-140°C for 1 h to give indolium and quinolinium salts in modest yields (18-38%). However, workup simply involved addition of the reaction mixture to ice-water to produce a homogeneous solution followed by the treatment with saturated aqueous KPF6 and extraction of the salt formed with HCCl3 or CH2Cl2. Spectral and elemental analyses supported the structures of the heterocyclic derivatives. A plausible mechanism involving the alkylation of a cation intermediate by the arene in a typical electrophilic substitution process is suggested for the salts carrying an arylmethyl group. In the case of the alkenylanilinium salts, the mechanism is not clear but rearrangements of the Claisen type appear to be operative.
There are various kinds of phosphoric acids and phosphates. Of the many , the constitute the largest and most diverse group. The simplest phosphoric acid series begins with monophosphoric (orthophosphoric) acid, continues with many oligophosphoric acids such as diphosphoric (pyrophosphoric) acid and concludes in the polyphosphoric acids. But, phosphoric acid units can bind together into rings or cyclic structures, chains (catenas), or branched structures, with various combinations possible. Each of these can form ( or of phosphoric acids).
The simplest of a series of phosphoric acids is sometimes called by its common name, , but more often called by its name, simply phosphoric acid, by both non-technical people and even many . It has also been called monophosphoric acid. The of orthophosphoric acid is H3PO4 and its is shown in the illustration below. Two or more orthophosphoric acid can be joined by into larger molecules by elimination of . This way, a series of polyphosphoric acids can be obtained.
Orthophosphoric acid has three to atoms in its structure. All three hydrogens are to varying degrees and can be lost from the as H+ ions (alternatively referred to as protons). When all three H+ ions are lost from orthophosphoric acid, an orthophosphate ion (PO43−) is formed. Orthophosphate is the simplest in a series of phosphates, and is usually just called phosphate by both non-technical people and many alike; see a separate article on for details.
Because orthophosphoric acid can undergo as many as three dissociations or ionizations (losses of H+ ions), it has three called Ka1, Ka2, and Ka3. Another way to provide acid dissociation constant data is to list pKa1, pKa2, and pKa3 instead. Orthophosphate is in a sense the triple of phosphoric acid and has three related , Kb1, Kb2, and Kb3, which likewise have corresponding pKb1, pKb2, and pKb3 values.
When two orthophosphoric acid molecules are condensed into one molecule, (H4P2O7) is obtained as follows:
The chemical structure of pyrophosphoric acid is also shown in the illustration. Three orthophosphoric acid molecules can condense in a row to obtain tripolyphosphoric acid (H5P3O10), which is also shown in the illustration. This condensation process can continue with additional orthophosphoric acid units to obtain tetrapolyphosphoric acid (H6P4O13, pictured) and so on. Note that each extra phosphoric unit adds 1 extra H () atom, 1 extra P () atom, and 3 extra O () atoms. The "backbone" chain of these types of molecules consists of alternating P and O atoms together. Polyphosphoric acid molecules can have dozens of such phosphoric units bonded in a row. A general formula for such poly-acid compounds is HO(PO2OH)xH, where x = number of phosphoric units in the molecule. The four oxygen atoms bonded to each phosphorus atom are in a tetrahedral configuration with the phosphorus in the center of the and the oxygens in each of the four corners.
Polyphosphoric acids are used in organic synthesis for cyclizations and acylations.