The Application Of Hantzsch Reaction In Hygienic Analytical Chemistry

Hantzsch reaction is a famous reaction commonly used to synthesize chemicals containing pyridine cycle. In this study the application of Hantzsch reaction in hygienic analytical chemistry was studied:1. According to the method mentioned in literature, we synthesized the chemical which can be used to analyze formaldehyde in acetyl acetate method. The chemical was studied with MS and NMR method and proved to be 2,6-Dimethyl-3,5-Diacetyl-1,4-Di- hydropyridine. The solution of the chemical was studied with ultraviolet spectrophotometry and the result showed the molar absorption coefficient of the chemical was 6.639x103 Lmol-1 cm-1 at 413nm. In practical determining process the maximum absorption wavelength of the chemical was at 415nm. This result corrected the inaccurate description about the determination of formaldehyde by spectrophotometry with acetyl acetate in Chinese publications.2. Acetylacetate ester can react with formaldehyde and ammonia to form a colored compound under weak acidic buffer of ammonium acetate. Using this reaction we established a new method to determine trace formaldehyde in food and environmental water, the maximum absorption of the product under chosen condition was at 375nm and molar absorption coefficient based on formaldehyde was 5.533x103 Lmol-1 cm-1; The measurement of formaldehyde obeyed Beer's law at the range of its concentration from 0.008mg/L to 0.40mg/L.3. The product formed by this method was proved to be 2,6-Ddimethyl -3,5-bis(ethoxycarbonyl) -1,4-dihydropyridine with MS analysis, demonstrating that the reaction in aqueous solution still followed the mechanism of Hantzsch' method for synthesizing pyridine. In comparison with acetyl acetate method we found that in the reaction process the concentration of enol-like compound had some effect on the reaction rate. The more the conctntration of enol-like compound, the lower the reaction temperature.4. A new method to indirectly determine Detrimine was established based on the mechanism of Hantzsch reaction. In acidic solution Detrimine was hydrolyzed in the presence of sulfuric acid, then the formaldehyde decomposed from Detrimine reacted with acetyl acetate in ammonium acetate buffer. The content of Detrimine was calculated from the concentration of formaldehyde. The linear range for determining Detrimine was between 5-40mg/Kg...