Karl Fischer & Potentiometric Titration Application Library
Ketones, Cyclohexanone – KF Coulometry, Cooled direct injection, Azeotropic distillation | Karl Fischer titrator AQ-300/MOICO-A19/EV-2000L
Water content of cyclohexanone is determined by Karl Fischer coulometric titrator. In coulometric titration, iodine of Karl Fischer reagent is generated by electrolysis and generated iodine quantitatively reacts with water. Reaction formula is described below.
H₂O ＋ I₂ ＋ SO₂ ＋ 3RN ＋ CH₃OH → 2RN・HI ＋ RN・HSO₄CH₃
2RN・HI → I₂ ＋ 2RN ＋ 2H⁺ ＋ 2e⁻
Ketones and aldehydes would interfere the Karl Fischer reaction by side-reaction with methanol (formula (1)).
R₂CO + 2CH₃OH → R₂C(OCH₃)₂ + H₂O ・・・(1)
Therefore it is necessary to use methanol-free anode and cathode solution. There are commercially available reagents with a special composition for ketones and aldehydes. However, cyclohexanone has particularly a strong side reaction activity, so it is difficult to measure by direct injection method at room temperature. In the measurement of cyclohexanone, it is effective to lower the activity of side reaction by cooling or to separate cyclohexanone and water by distillation.
This application introduces an example for the water determination in cyclohexanone with cooled direct injection method and azeotropic distillation method
H₂O ＋ I₂ ＋ SO₂ ＋ 3RN ＋ CH₃OH → 2RN・HI ＋ RN・HSO₄CH₃
2RN・HI → I₂ ＋ 2RN ＋ 2H⁺ ＋ 2e⁻
Ketones and aldehydes would interfere the Karl Fischer reaction by side-reaction with methanol (formula (1)).
R₂CO + 2CH₃OH → R₂C(OCH₃)₂ + H₂O ・・・(1)
Therefore it is necessary to use methanol-free anode and cathode solution. There are commercially available reagents with a special composition for ketones and aldehydes. However, cyclohexanone has particularly a strong side reaction activity, so it is difficult to measure by direct injection method at room temperature. In the measurement of cyclohexanone, it is effective to lower the activity of side reaction by cooling or to separate cyclohexanone and water by distillation.
This application introduces an example for the water determination in cyclohexanone with cooled direct injection method and azeotropic distillation method
Water Content in Oil Products by Karl Fischer Titration | ASTM D6304
Learn how Karl Fischer coulometric titration accurately determines trace moisture in petroleum products, lubricants, diesel fuel and oils using ASTM D6304 methods.
