Vanadous pyrophosphate

Vanadous Pyrophosphate, V4(P2O7)2.30H2O, is obtained as a green, floceulent predpitate when vanadium ammonium alum is added to a solution of an alkaline pyrophosphate.3... 

Gresser et al. [39] observed formation of mixed anhydrides of vanadate with phosphate and pyrophosphate in aqueous solutions by NMR, which may be... 

Weak complexes form between vanadate and phosphate, 9,99 pyrophosphate,59 arsenate,59 and chromate.106 The formation constant for the simple phosphovanadate is about 20 M 1." Structural characterization has been reported for interesting cluster structures of vanadium with organophosphonates107 and with sulfate.108 Divanadium(V) complexes with either monodentate or bidentate nitrate (N03 ) groups have been reported.109... 

The work was strongly inspired by Union Carbide s Ethoxene process, a route for manufacturing ethylene from ethane and oxygen by oxidative dehydrogenation. The first catalysts consisted of molybdenum, vanadium, and niobium oxides. The selectivity for ethylene was very high but, unfortunately, the conversion of ethane was low ( 10%). Therefore, scientists at the time focused on the co-production of ethylene and acetic acid. A catalyst consisting of molybdenum, vanadium, niobium, calcium, and antimony supported on a molecular sieve was developed (63% selectivity to acetic acid, 14% selectivity to ethylene, and 3% conversion of ethane). In addition, Rhone-Poulenc (catalyst vanadium oxide or vanadyl pyrophosphate) and BP (catalyst combination of rhenium and tungsten) patented processes for the production of acetic acid from ethane. Very efficient catalysts were also disclosed by Hoechst (molybdenum vanadate, promoted with Nb, Sb, Ca, and Pd, 250-280 °C, 15 bar, 86% selectivity to acetic add at 11% conversion of ethane per pass) and Sabic (phosphorus-modified molybdenum-niobium vanadate, 260 °C, 14 bar, 50% selectivity to acetic acid at 53% conversion of ethane). 

A chemico-enzymatic approach has been used for the synthesis of Coenzyme A analogues, modified in the thioethanolamine unit, using ATP as one starting material. Pyrophosphate bond formation from a nucleoside 5 -phosphorimidazolide catalysed by divalent metal ions (Mn2+, Cd + or Mg2+) has been used to make dinucleoside di- and tri-phosphates such as CppC and GpppG. A vanadate analogue of NADP is mentioned in Chapter 16, in connection with its ability to function as a redox cofactor. 

---