Reversible photochemistry of 1-methyl-4-ethoxycarbonylpyridinium iodide

✍ Scribed by P. Markov; M. Novkirishka

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 636 KB
• Volume: 46
• Category: Article
• ISSN: 1010-6030
• DOI: 10.1016/1010-6030(89)87052-2

✦ Synopsis

The effect of UV light on a methanol-water solution of l-methyl-4ethoxycarbonylpyridinium iodide was studied by spectroscopic and potentiometric methods. The irradiation of an air-saturated solution by UV light with a wavelength shorter than 240 nm initiates the formation of species which absorb at 358 nm. The photoprocess involved is not related to any change in the concentration of iodide ion. Irradiation at 280 nm or an increase in temperature of the solution containing the newly formed particles causes a reverse process and the gradual diminution of the concentration of these particles. The molar absorptivity E, of the complex, the equilibrium constant K,, of formation of the complex and the enthalpy N and entropy AS changes were determined.

In an atmosphere of argon, the irradiation of the solution causes a different effect which is manifested by the appearance of absorption at 345 nm.

A possible mechanism of the effect is discussed.