Tetrabutylammonium Hydroxide VS

Tetrabutylammonium Hydroxide VS C₁₆H₃₇NO = 259.5

For a 0.1m solution Dissolve 40 g of tetrabutylammonium iodide in 90 mL of anhydrous methanol, add 20 g of finely powdered silver oxide and shake vigorously for 1 hour. Centrifuge a few mL of the mixture and test the supernatant liquid for iodides. If a positive reaction is obtained, add a further 2 g of silver oxide and shake for 30 minutes. Repeat this procedure until the mixture is free from iodides, filter through a fine sintered-glass filter and wash the reaction vessel and filter with three 50-mL quantities of toluene. Add the washings to the filtrate and add sufficient toluene to produce 1000 mL. Pass dry carbon dioxide-free nitrogen through the solution for 5 minutes.

Ascertain its exact concentration immediately before use in the following manner. To 10 mL of dimethylformamide add 0.05 mL of a 0.3% w/v solution of thymol blue in methanol and titrate with the tetrabutylammonium hydroxide solution until a pure blue colour is produced. Immediately add 0.2 g of benzoic acid, stir to effect solution and titrate with the tetrabutylammonium hydroxide solution until the pure blue colour is restored. Protect the solution from atmospheric carbon dioxide throughout the titration. The volume of titrant used in the second titration represents the amount of tetrabutylammonium hydroxide required. Each mL of 0.1m tetrabutylammonium hydroxide VS is equivalent to 12.21 mg of C₇H₆O₂.