ABSTRACT
Paracetamol is a medication used to treat pain and fever (ASHSP, 2016). Various methods can be used in the analysis of paracetamol including ultra violet (UV) spectrophotometer, high profile liquid chromatography (Usifoh et al., 2002). A lot of these processes depend on the hydrolysis of paracetamol, leading to the formation of Schiff bases (a chromogen) with a substituted benzaldehyde. This study was carried out to synthesize and characterize (p-chlorobenzylidene-amino)-phenol and (p-methoxy-benzylidene-amino)-phenol and to determine their usefulness in the colorimetric determination of paracetamol.
p-Aminophenol (0.01 mol) was dissolved in 25 ml of methanol in a round bottom flask, heated for 10 minutes and thereafter, the p-chlorobenzaldehyde (0.01 mol) was added. The mixture refluxed for 4 hours. The process was repeated using p-methoxy-benzaldehyde (0.01 mol) as the aldehyde. The products: (p-chlorobenzylidene-amino)-phenol and (p-methoxybenzylidene-amino)-phenol were characterised spectroscopically (IR, NMR, MS). The resulting coloured solutions of both chromogens were scanned individually between the wavelength range of 370 nm to 750 nm to obtain the wavelength of maximum absorption after a baseline correction was done using the reagent blank.
The spectrum from the IR spectroscopy of the (p-chlorobenzylidene-amino)-phenol confirmed the presence of various functional groups such as double bond (1620.73 cm-1. The spectrum of the infrared spectroscopy of the (p-methoxybenzylidene-amino)-phenol revealed the presence of double bond (1622.01cm -1), aromatic ring (1504.15cm -1) and hydrocarbons (3059.50cm-1). Nuclear magnetic resonance images of both chromogens revealed the same number of hydrogens and carbons as identified by elemental analysis and also, the relationship between the functional groups were confirmed. (p-Chlorobenzylidene-amino)-phenol and (p-methoxybenzylidene-amino)-phenol had maximum absorption wavelengths of 377 nm and 374 nm respectively. The calibration curve for both chromogens obeyed the Beer-Lambert’s law, having a regression coefficient of 0.998 and 0.997 respectively. The percentage yield for the (p-chlorobenzylidene-amino)-phenol and (p-methoxybenzylidene-amino)-phenol 69.5% and 78.1% respectively.(p-Chlorobenzylidene-amino)-phenol and (p-methoxybenzylidene-amino)-phenol have been synthesized and characterized and their possible utilization in the colorimetric determination of paracetamol has been established as they have been found to obey the Beer-Lambert’s law for absorption of light.
