Disodium hydrogenphosphate

Buffer solution. Dissolve 4.5 g of disodium hydrogenphosphate in 1 L of distilled water and carefully add 0.1M sodium hydroxide solution to give a pH of 10.2-10.4 (pH meter). 

The pigments are obtained by preparing an aqueous solution of disodium hydrogenphosphate and adding a sodium molybdate solution (containing molybdenum trioxide and aqueous sodium hydroxide). Acidified with hydrochloric acid or with sulfuric acid, the reaction mixture is then added to an aqueous solution of the... 

Dipotassium hydrogen phosphate trihydrate (15.9 g), potassium dihydrogen phosphate (4.0g), disodium hydrogenphosphate dodecahydrate (7 g), ammonium sulfate... 

In this system the weak acid is sodium dihydrogenphosphate (NaH2P04) and the weak base is disodium hydrogenphosphate (Na2HP04). The action of the buffer system is similar to that of the hydrogencarbonate system. 

The reduction of the p-acyloxy sulfone is most often carried out with sodium amalgam, as the examples below indicate. The reductive elimination can be buffered with disodium hydrogenphosphate for sensitive substrates. In certain applications it has proven advantageous to utilize lithium or sodium in ammonia. For example, Keck s synthesis of pseudomonic acid C made use of the lithium/ammonia reductive elimination to simultaneously form an alkene and deprotect a benzyl ether.In studies directed toward the same target, Williams made use of a reductive elimination procedure developed by Lythgoe, involving the formation of the xanthate ester followed by reduction with tri-n-butyltin hydride. ... 

A mixture of sodium dihydrogenphosphate, Na+H2PO and disodium hydrogenphosphate, (Na+)2HP04, will function as a buffer and control the pH to a value of approximately 7.0. In this example, the species with the greater number of available hydrogen atoms functions as the acid,... 

HBA and PhBA-Na were dissolved in pH 12 disodium hydrogenphosphate-NaOH buffer solution and in water, respectively. The drug concentration in injections was 215.3 ijmol/10 ml. The stability constants of drug-3-CD systems, and pH and osmotic pressure values of injections are listed in Table I. 

Several hydrates of disodium hydrogenphosphate have been reported. Wendrow and Kobe (4) stated that the transition temperatures of the dodecahydrate to the heptahydrate and of the heptahydrate to the dlhydrate were 308.7 and 321.2 K, respectively. A more precise determination of these values (6) gives transition temperatures of 308.55 and 321.55 K, respectively. There is also a report of the existence of two forms of the dodecahydrate with a transition temperature of 302.8 K (2), but this has not been confirmed by any other investigators. The transition temperature of the dihydrate to the anhydrous salt was said to be 368.2 K (4). 

COMPONENTS (1) Disodium hydrogenphosphate Na HPO [7558-79-4] (2) Water H O [7732-18-5] EVALUATOR J. Eysseltova Charles University Prague, Czechoslovakia May 1985 ... 

---