Preparation and standardization of Sodium Methoxide titrant (0.1 N) in Toluene
1. PREPARATION :
Weigh accurately about 5.402 g Sodium Methoxide powder in 1000 mL volumetric flask and add 200 mL of Methanol and make up the volume upto the mark with Toluene.
2. STANDARDISATION :
Accurately weigh about 400 mg of primary standard Benzoic acid, and dissolve in 80 mL of Dimethylformamide in a flask. Add 3 drops of a 1 in 100 solution of Thymol blue in Dimethylformamide and titrate with the Sodium methoxide to a blue endpoint. Correct for the volume of the sodium methoxide solution consumed by 80 mL of the Dimethylformamide.
Each 12.21 mg of Benzoic acid is equivalent to 1 mL of 0.1 N Sodium methoxide.
Normality = [Wt. of Benzoic acid in mg] /1[22.1 x mL of Sodium methoxide (corrected for the blank)]
(1) To eliminate any turbidity that may form following dilution with Toluene, add Methanol (25 to 30 mL) usually suffices) until the solution is clear.
(2) Restandardize the solution frequently.
Limit : 0.1 N ± 5 % (0.0950 N – 0.1050 N)
3. STORAGE CONDITION :
This solution is to be stored in suitable reagent bottle. Protect it from moisture and Carbon dioxide.