Pyrophosphoric acid catalyst

The condensation of cyclohexanol or cyclohexene is generally carried out in the presence of phosphoric acid, pyrophosphoric acid, or HY 2eohtes the aromatization of intermediate cyclohexyUiydroquinone [4197-75-5] (19) is realized in the presence of a dehydrogenation catalyst. 

Orthophosphoric acid and pyrophosphoric acid are preferred catalysts. Phosphorus pentoxide is catalytically active but no conclusive evidence has been described to show whether or not its activity depends on the presence of traces of water as promoter. Copper pyrophosphate and acid phosphates of cadmium are also good catalysts that the former probably owes its activity to partial conversion to acid or acidic salt under the polymerization conditions seems to be shown by the fact that there is an induction period. A composite prepared by calcining kiesel-guhr impregnated with orthophosphoric acid (the so-called solid phosphoric acid ) has found wide commercial use. 

Hydrogen ion (H ) and hydroxyl ion OH ) are common catalysts in aquatic systems. The effect of their catalysis is manifested by changes in reaction rate that occur with changes in pH. For example, one of the major constituents of household synthetic detergents is the salt of condensed phosphoric acid such as pyrophosphoric acid, H4P2O7, and tripo-lyphosphoric acid, H5P3OKJ, These compounds react with water in a reaction known as hydrolysis to form orthophosphoric acid thus ... 

Methyl cis-2-methoxycinnamate stirred into pyrophosphoric acid with initial cooling to maintain room temp., and allowed to stand 3 hrs. with occasional stirring coumarin. Y 79%.—Gleavage of the methoxyl group occurs with remarkable ease. The trans-isomer remains unchanged under the above conditions. F. e., limitations, and catalyst specificity, s. M. Narayana, J. F. Dash, and P. D. Gardner, J. Org. Ghem. 27, 4704 (1962). 

So-called 100% acid is a mixture comprising 88% orthophosphoric acid, 6% pyrophosphporic acid and 6% water. The optimum catalyst for the alkylation reaction contains 102%> phosphoric acid and therefore contains an even higher concentration of pyrophosphoric acid. 

Nucleotide derivatives. Dry adenosine-5 -phosphoric acid stirred with -carb-ethoxy-a-ethoxyvinyl diethyl phosphate and tri-n-butylamine in abs. dimethyl-formamide until dissolved after 2-3 days, dil. with acetone and the product precipitated with a soln. of anhydrous Nal in acetone Na P -(5 -adenosyl) P -diethyl diphosphate (Y 87 % as the monohydrate) warmed 3 hrs. at 50° in abs. methanol-pyridine, and the product isolated as the NH4-salt NH4 5 -adenosine methyl phosphate (Y 79.2% as the monohydrate).—Pyrophosphoric acid esters react with alcohols, amines, and acids so that the monoester part appears in the product. The adenosine-5 -phosphoric acid group in the intermediate triester is activated and can be easily combined with various nucleophiles. F. e. without isolation of the intermediate s. F. Cramer and R. Witt-mann. B. 9A, 328 (1961) s. a. B. 94, 322 dimethylformamide as phosphorylation catalyst s. B, 94, 989. 

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