Mahmoud Mohamed Sidky

ORGANOPHOSPHORUS CHEMISTRY, 11.1 THE 1:2 ADDITION OF ALKYL PHOSPHITES TO 3-METHYLENE-OXINDOLES. A NEW TYPE OF ATTACK BY TERVALENT PHOSPHITE ESTERS ON α,β-UNSATURATED CARBONYL COMPOUNDS

Abstract The addition of trialkyl phosphites 2a,b to 3-methylene-oxindoles, &,b proceeded according to the 1:2 pattern to give 13a-d as major products. Compounds 14s-d (<10%) were also isolated and identified from the same reactions. Compounds 14 were exclusively obtained when controlled amounts of water were present in the reaction medium or when &,b were reacted with the appropriate dialkyl phosphite (15). Analytical and spectroscopic (IR, 1H, 31P, 13C NMR and MS) measurements are compatible with the proposed structures.

Photochemical reactions of bianthrone and related substances

Abstract Photocleavage reactions of a wide range of ethylene compounds were investigated. Photosensitized oxygenation resulted in formation of their corresponding ketones. On the other hand, photoreaction of these substrates with elemental sulfur yielded the corresponding thioketones. Furthermore, photobehaviour of some ethylene episulfides also was studied. It could be concluded that UV-irradiation provides a rapid and effective desactivation pathway for this class of compounds.

ORGANOPHOSPHORUS CHEMISTRY 10. THE BEHAVIOUR OF β-AROYLACRYLIC ACIDS TOWARD NUCLEOPHILIC PHOSPHORUS COMPOUNDS

Abstract The reaction of alkyl phosphites and thiolphosphoric acids with β-aroylacrylic acids 1a,b has been investigated. Dialkyl phosphites (DAP) attacked 1 at the β-carbon atom with respect to the aroyl-carbonyl function, to give phosphonate 1:1 adducts assigned structure 2A. Thiolphosphoric acids (7) attacked 1 at the same centre to give adducts 8. On the other hand, trialkyl phosphites (TAP) converted 1 into the respective esters 5, almost exclusively. Structures of the new products were assigned according to consistent analytical and spectroscopic measurements.

THE REACTION OF ALKYL PHOSPHITES WITH 3,5-DI-TERT-BUTYL-1,2-BENZOQUINONE. VARIABLE TEMPERATURE NMR STUDIES ON NEW PENTAOXYPHOSPHORANES

Abstract 3,5-Di-tert-butyl-1,2-benzoquinone (5) reacts with trialkyl phosphites (6) to give the respective penta-oxyphosphoranes 7. On the other hand, the reaction of quinone 5 with dialkyl phosphites affords the phosphonate adducts 13. Analytical and spectroscopic (1H, 31P. 19F and 13C NMR) results are in accord with the given structures. The ground state structure of pentaoxyphosphoranes 7 was also studied in the light of NMR time scale spectroscopic results.

Organophosphorus compounds—XIX : The reaction of trialkyl phosphites with extended p-quinones

Abstract Trimethyl and triethyl phosphites react with diphenoquinone 3, yielding 4,4′-dihydroxydiphenyl 10; 4′-alkoxy-4-biphenylyl dialkyl phosphates 5, 4,4′-biphenylylene tetraalkyl bis(phosphates), 6, and 4′-hydroxy-4-biphenylyl dialkyl phosphates 9 are also isolated in minor yields. The effect of temperature on the reaction is studied. A mechanism for the reaction is presented which accounts for the experimental results. The reaction of trimethyl and triethyl phosphites with quinoneimines 12 gives the corresponding phosphoramidates 13, in quantitative yields.

PHOTOCHEMISTRY OF PESTICIDES, 13.1 SOME PHOTOREACTIONS OF O,O-DIETHYL-O-(4-METHYL-2-OXO-2H-1-BENZOPYRAN-7-YL)-PHOSPHOROTHIOATE (POTASAN®)

Abstract UV-irradiation (δ > 313nm) of O,O-diethyl-O-(4-methyl-2-oxo-2H-1-benzopyran-7-yl)-phosphoro-thioate (Potasan®) la in chloroform and/or methanol with and without singlet oxygen results in the formation of the 2-oxo-2H-1-benzopyran-phosphate 2 the 3,3′-bipotasan dehydrodimer 3, and 7-ethoxy-4-methyl-2-oxo-2H-1-benzopyran 4: the mechanisms of formation, especially for 4 are discussed.

PHOTOCHEMISTRY OF PESTICIDES, 71. REGIOSELECTIVE PHOTODIMERIZATION OF o,o-DIETHYL-o-(3-CHLORO-4-METHYLCOUMARIN-7-YL)-THIOPHOSPHATE (COUMAPHOS)

Abstract UV-irradiation (λ > 313 nm) of o,o-diethyl-o-(3-chloro-4-methyl-coumarin-7-yl)-thiophosphate (Coumaphos; 1) in chloroform results in an regioselective dimerization reaction to afford the head-to-tail anti-dimer 2. The structure of 2 is established by single crystal x-ray diffraction. Singlet oxygen does not affect the formation of 2.

Photochemistry of Pesticides, 10 [1] Photodegradation of O,O-Diethyl-S(3,4-dihydro-4-oxobenzo[d][1,2,3]triazin- 3-yl-methyl)phosphorodithioate (Azinphos-ethyl)

Abstract The photodegradation of Azinphos-ethyl (1) in chloroform and methanol solution has been studied. 3,4-Dihydro-3-methyl-4-oxobenzo[d][1,2,3]triazine (3), 3,4-dihydro-4-oxo-benzo[d]- [1,2,3]triazine (5), O,O-diethyl-O(3-methylbenzo[d][1,2,3]triazine-4-yl)p hosph ate (8), N-methylanthranilic acid (11) (in methanol: methyl ester 12), and sulfur have been isolated and characterized as photoproducts. The decay mechanism is discussed.

Zum Photoabbau von l-(4-Chlorphenyl)-4,4-dimethyl-3-(1H-1,2,4-triazoll- ylmethyl)-pentan-3-ol (Folicur®) [1] / On the Photodegration of l-(4-Chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-triazol-l-ylmethyl)-pentan-3-ol (Folicur®) [1]

The photodegradation of the 1,2,4-triazole fungicide Folicur 1 in different organic solvents (benzene, ether, methylene chloride, methanol) and water, in absence and in presence of a singlet oxygen sensitizer (methylene blue) has been studied. The photometabolites formed in organic solvents, have been separated by column chromatography (with isolation of 4 -7 , 13 and 14) and in the case of benzene as solvent as well with the aid of HPLC (isolated: 4 -7 , and five additional products 8-12). Photodegradation of 1 in water leads to the formation of only two photoproducts: 4 and 17 (separated only by HPLC). Identification has been achieved by spectroscopic methods and comparison (of retention times, UV and mass spectra) with authentic samples. Furthermore, the kinetics of the photodegradation of 1 in benzene and water (also after addition of titanium dioxide) has been established by HPLC-UV/VIS-technique. The interpretation of the kinetics allows conclusions towards the photodegradationmechanism, which is discussed in the paper. As expected, the addition of the photocatalyst titanium dioxide leads to a significant acceleration of the photodegradation.