Preparation and standardization of Sodium Methoxide titrant (0.1 N) in Toluene


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.


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.

Calculation :

Normality = [Wt. of Benzoic acid in mg] /1[22.1  x  mL of Sodium methoxide (corrected for the blank)]

Note :  

(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)


This solution is to be stored in suitable reagent bottle. Protect it from moisture and Carbon dioxide.

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