Silver nitrate reaction with NaOH

Self-Test 9.2A Write the equilibrium constant for the reaction of silver nitrate with I sodium hydroxide 2 AgN03(aq) + 2 NaOH(aq) Ag20(s) + 2 NaN03(aq) + i H20(1). Remember to use the net ionic equation. 

Add N-acetyl homocysteine thiolactone (Aldrich) to the bicarbonate reaction mixture to obtain a concentration representing a 10- to 20-fold excess over the amount of amines present. For protein thiolation, add the same molar excess of thiolactone reagent to the water reaction medium, and then slowly add an equivalent molar quantity of silver nitrate (AgNO j). Maintain the pH at 7.0-7.5 with periodic addition of NaOH. 

Ammonium was tested for in preliminary test 6 (Section V.2). By heating the original substance with NaOH solution, NH3 will be evolved from ammonium salts. The NH3 gas may be identified by its odour, by its action upon red litmus paper or upon filter paper moistened with mercury(I) nitrate solution, or by the tannic a cid-silver nitrate test (Section III.38, reaction 7). The insertion of a loose plug of cotton wool in the upper part of the tube will eliminate the danger of NaOH solution spray affecting the reagent paper. 

To a stirred solution of heteroarene (2 0.4 mmol) in dichloromethane (1.5 mL) at ambient temperature under open-flask was added TFA (0.32 mL) and triazene (1 0.6 mmol), the mixture was then stirred vigorously for 5 min. Then water (1.5 mL) and silver nitrate solution (20 mol % in 1.0 mL water) and potassium persulfate (0.32 g) was added successively, and the stirring was continued up to 24 h (TLC monitored). Upon completion of the reaction, 2N NaOH was added to quench excess TFA, extracted with dichlorometahne (5 x 20 mL), and dried over anhydrous sodium sulfate. Solvent was evaporated under reduced pressure and the crude residue was purified by silica gel flash chromatography (10% MeOH in CH2CI2) to furnish pure substituted het-eroaren 3, characterized by means of spectral studies. 

---