Phosphomolybdic acid/hydrogen peroxide

Fig. 18b.9. Example cychc voltammograms due to (a) multi-electron transfer redox reaction two-step reduction of methyl viologen MV2++e = MV++e = MV. (b) ferrocene confined as covalently attached surface-modified electroactive species—peaks show no diffusion tail, (c) follow-up chemical reaction A and C are electroactive, C is produced from B through irreversible chemical conversion of B, and (d) electrocatalysis of hydrogen peroxide decomposition by phosphomolybdic acid adsorbed on a graphite electrode.

The phosphorus content can be determined by wet oxidation of the starch with sulfuric (or nitric) acid and hydrogen peroxide followed by colorimetric estimation of the phosphomolybdate complex. A detailed procedure for gravimetric determination can be found in AACC method 40-57 (AACC, 2000). However, large sample sizes (2-5 g) are required in this method. 

Chrom Q (60-80 mesh), 170°C, 50 mL of nitrogen per min. The retention times for the perhydrophenaienol and dioxaborole are 6.4 and 15.2 min, respectively. For TLC analyses, Analtech silica gel plates bearing the material were eluted by 1 2 methylene chloride-petroleum ether, and visualized with phosphomolybdic acid perhydrophenaienol, Rf 0.4 dioxaborole, Rf 0.9. The checkers found that the reaction was essentially complete after addition of the hydrogen peroxide. Additional heating did not lower the yield of product. 

Phosphorus can serve as a benehcial adjunct or as a deleterious agent. There are several test methods for the determination of phosphorus. In addition to the three test methods described here, reference should also be made to multielement analysis methods such as inductively coupled plasma atomic emission spectroscopy (ICPAES) (ASTM D-4951, ASTM D-5185) and X-ray fluorescence (XRF) (ASTM D-4927, ASTM D-6443) described above in this guide. Phosphorus can also be determined by a photometric procedure (IP 148) or by a test method (ASTM D-1091) in which the organic material in the sample is destroyed, phosphorus in the sample is converted to phosphate ion by oxidation with sulfuric acid, nitric acid, and hydrogen peroxide, and the magnesium pyrophosphate is determined gravimetrically. Another method (ASTM D-4047, IP 149) in which the phosphorus is converted to quinoline phosphomolybdate is also available. 

The peroxidation of P,6-triketones with an ethereal solution of hydrogen peroxide promoted by phosphomolybdic acid (PMA) in the presence of acetonitrile is substrate-controlled unsubstituted triketones, or those containing aliphatic substituents, produce only tricyclic monoperoxides 32 triketones containing benzyl substituents afford tricyclic monoperoxides 32, bridged tetraoxanes 33, and stereoisomeric ozonides 34 and 35 (Scheme 85) (14CEJ10160). 

Hydrogen peroxide s. under Phosphomolybdic acid Sulfuric acid s, under KMnO ... 

---