Photodecomposition of an acaricide, fenazaquin, in aqueous alcoholic solution.
Fenazaquin (I) is a new acaricide of the quinazoline class. The photodecomposition of I was studied in aqueous methanolic and 2-propanolic solution under UV light (30 h) and sunlight (70 h) separately. The photolytic half-lives in aqueous methanolic solution were found to be 17.1 h (UV) and 38.1 h (sunlight), whereas these were 12.9 h (UV) and 29.2 h (sunlight) for aqueous 2-propanolic solution; all followed a first-order reaction kinetics. Six photoproducts were obtained: beta-phenyl (p-tert-butyl) ethyl alcohol (II), 4-hydroxyquinazoline (III), p-tert-butyl vinyl benzene (IV), 2,4-dihydroxyquinazoline (V), phenyl (p-tert-butyl) acetic acid (VI), and 2-methyl-2-[4'-(2' '-hydroxyethyl)phenyl]propanoic acid (VII). Compounds VI and VII could be isolated only from aqueous 2-propanolic solution under sunlight irradiation. The major degradation products are formed as a result of cleavage of the ether bridge linking the quinazoline and phenyl ring systems of the molecule, oxidation of the tert-butyl substituent, and oxidation of the heterocyclic portion of the quinazoline ring. A probable mechanism of formation of the photoproducts is also suggested.
Bhattacharyya
Jayati
J
Pesticide Residue Laboratory, Department of Agricultural Chemicals, Faculty of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur 741 252, West Bengal, India.
Banerjee
Hemanta
H
Bhattacharyya
Anjan
A
D019840:2-Propanol; D000818:Animals; D006207:Half-Life; D007306:Insecticides / Q000737:chemistry; D007700:Kinetics; D000432:Methanol; D008925:Mites; D010777:Photochemistry; D010782:Photolysis; D011799:Quinazolines / Q000737:chemistry*; D012996:Solutions; D013472:Sunlight; D014466:Ultraviolet Rays; D014867:Water
D007306:Insecticides; D011799:Quinazolines; D012996:Solutions; D014867:Water; C087876:fenazaquin; D019840:2-Propanol; D000432:Methanol