Phosphoric acid metal complexes

Aromatic amines form addition compounds and complexes with many inorganic substances, such as ziac chloride, copper chloride, uranium tetrachloride, or boron trifluoride. Various metals react with the amino group to form metal anilides and hydrochloric, sulfuric, or phosphoric acid salts of aniline are important intermediates in the dye industry. 

A method suitable for analysis of sulfur dioxide in ambient air and sensitive to 0.003—5 ppm involves aspirating a measured air sample through a solution of potassium or sodium tetrachloromercurate, with the resultant formation of a dichlorosulfitomercurate. Ethylenediaminetetraacetic acid (EDTA) disodium salt is added to this solution to complex heavy metals which can interfere by oxidation of the sulfur dioxide. The sample is also treated with 0.6 wt % sulfamic acid to destroy any nitrite anions. Then the sample is treated with formaldehyde and specially purified acid-bleached rosaniline containing phosphoric acid to control pH. This reacts with the dichlorosulfitomercurate to form an intensely colored rosaniline—methanesulfonic acid. The pH of the solution is adjusted to 1.6 0.1 with phosphoric acid, and the absorbance is read spectrophotometricaHy at 548 nm (273). 

The reactions which take place when the mixed etch primer is applied to a metal are complex. Part of the phosphoric acid reacts with the zinc tetroxychromate pigment to form chromic acid, zinc phospliates and zinc chromates of lower basicity. The phosphoric acid also attacks the metal surface and forms on it a thin chromate-sealed phosphate film. Chromic acid is reduced by the alcohols in the presence of phosphoric acid to form chromium phosphate and aldehydes. It is believed that part of the chromium phosphate then reacts with the resin to form an insoluble complex. Excess zinc tetroxy chromate, and perhaps some more soluble less basic zinc chromes, remain to function as normal chromate pigments, i.e. to impart chromate to water penetrating the film during exposure. Although the primer film is hard... 

Levelling acid dyes and particularly 1 1 metal-complex types generally require an exceptionally low pH in order to promote exhaustion and levelling up to 3% o.w.f. sulphuric acid is most commonly used for levelling acid dyes, although hydrochloric, formic and phosphoric acids are also effective. In the case of conventional 1 1 metal-complex dyes it is essential to use a sufficient excess of acid over and above the typical 4% o.w.f. sulphuric acid normally absorbed by the wool, otherwise there may be a tendency towards tippy dyeings and lower wet fastness. The actual excess required depends on applied depth and liquor ratio [2] typical recommendations are given in Table 12.2. 

Diselenophosphates have been much less investigated than the analogous dithiophosphates, but some interesting chemistry was revealed. The reactions of phosphorus(V) selenide, P2Se5, with alcohols and phenols produce diseleno-phosphoric acid diesters, (RO)2P(Se)SeH, the parent compounds of di-selenophosphato anionic ligands. The free acids are not stable and should be immediately converted to metal salts or complexes. 

Adex A process for removing heavy metals from phosphoric acid by precipitation of their complexes with 2-ethylhexyl dithiophosphate. Developed by Hoechst, Germany. 

Phosphate (or, Orthophosphate) or PO/ . The conjugate base of HP04 , one of the 0x0 anions of phosphoric acid (the values of H3PO4 are, at 25°C, 2.15, 7.20, and 12.33). The structure of the resonance-stabi-hzed P04 is tetrahedral and can form complexes with metal ions and other cations. 

A number of compounds containing phosphorus-metal bonds exhibit an interesting reactivity. In platinum (II) complexes, coordinated PC13 undergoes solvolysis reactions with water and alcohols to form stable orthophosphite esters or phosphorous acid (Equation 32) (66, 67). 

---