Diphosphate Manganese Pyrophosphate

Submitted by B. DURAND and J. M. PARIS Checked by E. KOSTINERt and M. H. RAPPOSCHt 

Owing to its stability, manganese diphosphate is very convenient as a calibrant for magnetic susceptibility measurements. Its magnetic susceptibility follows the Curie-Weiss law between -80 and +485°. 

Sodium diphosphate is prepared by the following procedure. Disodium hydrogen phosphate dihydrate, Na2HP04 2H20, (7.12 g, 40 mmole) is placed in a 60-mL platinum crucible and heated in air at 400° for 12 hours (Product Merck for analysis K 6580). According to Porthault,2 this method leads to a tetrasodium diphosphate, Na4P207, the purity of which is better than 99.5%. No impurities can be found by chromatographic or potentiometric analysis. 

The eutectic MnCl2 2.03KCl and the phosphate Na4P207 are quickly mixed by milling in air in an agate mortar so as to avoid as much as possible the hydratation of the salt. To get a rapid and complete reaction an excess of eutectic is used 5.32 g Na4P207 (2 X 10 2 mole) for 22.17 g of eutectic (8 X 10 2 mole). 

The reaction mixture is placed in a 60-mL platinum crucible, heated in a nonoxidizing atmosphere at 500° in a regulated furnace (temperature rise 150°/hr), and held there for 24 hours. The nonoxidizing atmosphere is produced by a stream of pure nitrogen that has been dried by passage over P2Os. 

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Pyrolusite, see Manganese(IV) oxide Pyrophanite, see Manganese titanate(IV)(2—) Pyrophosphate, see Diphosphate(V)... 

This enzyme [EC 2.5.1.17], also referred to as cob(I)-alamin adenosyltransferase or aquacob(I)alamin adeno-syltransferase, catalyzes the reaction of cob(I)alamin with ATP and water to produce adenosylcobalamin, orthophosphate, and pyrophosphate (or, diphosphate). A cofactor for this enzyme is manganese ion. 

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