Monograph - Metrohm

4 Apparatus and accessories used- 702, 716, 736, 751 or 785 Titrino or 726 Titroprocessor, 728 Magnetic stirrer,Metrodata TiNet software, printer and PC- 6.3014.223 Exchange Units- 6.0229.100 Solvotrode*; electrolyte a) 6.2312.000 LiCl sat. in ethanol, electrolyteb) 6.2320.000 TEA-Br 0.4 mol/L in ethylene glycol5 Titration of acidsThe titrations were carried out in the «pH range»** of the titrator in the MET mode(volume increments 0.10 mL, fixed delay period 5 s).Electrodes1) 6.0229.100 Solvotrode, electrolyte LiCl sat. in ethanol2) 6.0229.100 Solvotrode, electrolyte TEA-Br c = 0.4 mol/L in ethylene glycol(TEA-Br = tetraethyl ammonium bromide)Acids tested (0.1 mol/L in ethanol)- Benzoic acid; pK A = 4.20- Phenol; pK A = 9.95Apparatus and accessories used – Titration of acidsTitrantsa) c(TBAOH) = 0.1 mol/L in IPA (TBAOH = tetrabutyl ammonium hydroxide, IPA= isopropanol)b) c(KOH) = 0.1 mol/L in IPASolventsEthanolMethyl isobutyl ketone (MIBK)Isopropanol (IPA)Dimethyl formamide (DMF)tert. Butanol/IPA 95:5PyridineAcetoneAcetonitrile2.50 mL of the tested acid was treated with 50 mL of the corresponding solventand titrated with TBAOH or KOH.* The Solvotrode is a combined pH glass electrode developed specially for non-aqueoustitrations.** The concept of pH really applies only to purely aqueous solutions. In organic solvents thevalues are displaced. The neutral point is no longer at «pH = 7» and negative values or valuesup to 20 can occur (extension of the pH scale). This means that at «high» pH values highalkali errors must be expected with glass electrodes.Non-aqueous titration of acids and bases with potentiometric endpoint indication 9