Determination of potassium, ammonium, rubidium, and cesium.
Sodium Tetraphenylboroate is a salt that is commonly used in inorganic and organometallic chemistry as a precipitating agent. Sodium Tetraphenylboroate is also utilized for the preparation of N-acylam
monium salts and in coordination chemistry due to their favourable solubility in nonpolar sovlents and their crystallinity.
As reagent for determination of potassium, ammonium, rubidium and cesium ions: Barnard, Buechl, Chemist-Analyst 48, 44, 49 (1959); Montequi, Serrano, An. R. Acad. Farm. 26, 107 (1960).
Sodium tetraphenylborate (Ph4BNa) undergoes rhodium-catalyzed addition reactions with N-phenylsulfonyl aldimines to afford R(Ph)CHNHSO2Ph.
Dissolve the borate in dry MeOH and add dry Et2O. Collect the solid and dry it in a vacuum at 80o/2mm for 4hours. It can also be extracted (Soxhlet) using CHCl3, and it crystallises from CHCl3 as snow-white needles. It is freely soluble in H2O, Me2CO but insoluble in pet ether and Et2O. An aqueous solution has pH 5 and can be stored for days at 25 or lower, and for 5 days at 45o without deterioration. Its solubility in polar solvents increases with decrease in temperature [Wittig & Raff Justus Liebigs Ann Chem 573 204 1950]. The salt can also be recrystallised from acetone/hexane or CHCl3, or from Et2O/cyclohexane (3:2) by warming the solution to precipitate the compound. Dry it in a vacuum at 80o. It dissolves in Me2CO at 50-60o to give a clear solution. After standing at this temperature for 10minutes the mixture is filtered rapidly through a pre-heated Büchner funnel, cooled and the crystals are collected and dried in a vacuum desiccator at room temperature for 3days [Abraham et al. J Chem Soc, Faraday Trans 1 80 489 1984]. If the product gives a turbid aqueous solution, the turbidity can be removed by treating with freshly prepared alumina gel and filtering. [Beilstein 16 IV 1624.]
