Thermodynamic, kinetic, and Spectrophotometric
Determination of Anti-hypertension Drug in Bulk and
Pharmaceutical Preparation by Oxidative Coupling Reaction
الباحث الأول:
م.م وسن نجم عبدالله
الباحثين الآخرين:
أ.د مثنى صالح مشكور
أ.م.د هناء كاظم كزار
المجلة:
https://sites.google.com/view/alharafmagazin
تاريخ النشر:
24 ديسمبر، 2024
مختصر البحث:
A simple and sensitive spectrophotometric process has been developed to detect the anti-
hypertensive medication clonidine hydrochloride (CH). The process is based on the oxidative
coupling reaction of CH in an alkaline medium with 2,4-dinitroph…
A simple and sensitive spectrophotometric process has been developed to detect the anti-
hypertensive medication clonidine hydrochloride (CH). The process is based on the oxidative
coupling reaction of CH in an alkaline medium with 2,4-dinitrophenylhydrazine (2,4-DNPH)
and potassium iodate (KIO3). The reaction produces a bright light orange product that is water-
soluble, with maximum absorption at 450 nm and a molar absorptivity Ԑmax of 1.3×103 mol.L-1
.cm-
1
. A linear relationship was observed between the concentration and absorbance in the range of)
25-250( μg. mL-1
. It was determined that the colored product has a 1:1 stoichiometry between CH
and 2,4-DNPH. At 25°C, the stability constant, and degree of association were found to be )
0.765 × 108
( and )0.0185( respectively. The proposed method was successfully applied to detect
CH in )100( μg.mL-1 pharmaceutical tablet formulations. The kinetic study of the reaction
revealed a pseudo-zero order reaction, the rate constant was determined at different temperatures.
The heat of formation (∆H0), free energy (∆G0) and entropy (∆S0) of the reaction product were
determined to be )16.22( kJmol-1
,) 54.2(kJmol-1
and) -127.7( J.mol-1 K-1
respectivily.
Keywords: Clonidine hydrochloride , 2,4-dinitrophenylhydrazine, oxidative coupling reaction,
spectrophotometric detection , kinetic and thermodynamic.
