Syntheses Of Isothiazole And Their Intermediate Derivatives

Isotianil（3,4-dichloro-N-（2-cyanophenyl）-5-isothiazolecarboxamide）is firstlyknown bactericide that is low-used,environmental friendly and inducible,mainly for the prevention and control of the rice blast.However,the production process of isotianil has problems in lower yield along with lower purity.For this reason,syntheses of isothiazoles and the synthetic route of isothiazide-type products and their intermediate derivatives are systemtically summarized and practically reveived in this thesis.And designed syntheses and structural analyses of isothiazoles and their intermediate derivatives are reported for the first time.The effects of reactive factors such as recrystallization of raw materials,the ratio of raw materials,temperature,time and recrystallization solvents on the yield of isotianil have been investigated in the thesis,optimistacally the recrystallized3,4-dichloroisothiazol-5-carbonitrile was directly chosen as a starting materials,and them by using of the hydrolysis reaction,chloride acetylation,Friedel-Crafts reaction,eliminatoin reaction and crystallization,the isothiafen product with stable properties along with high purity and high yield could be repeatedly synthesized.The obtained product was characterized by¹H NMR,¹³C NMR,FT-IR spectroscopies along with the HPLC testing.The molecular structure of isotianil was established by single-crystal X-ray diffraction,and the aggreatration and arrangement of inert drug molecules in the unit cell were analyzed in detail.The final product yield may reach 86%and the purity is as high as 98%.The amide group in the structure of isotianil is a pharmacophore.Based upon the experimental conditions,a series of 3,4-dichloroisothiazole carboxamides derivatives and 3,5-dichlorobenzamide derivatives were synthesized.All of the synthesized compounds were characterized by ¹H NMR,FT-IR and UV-Vis spectroscopic.Molecular structures of 3,5-dichloro-N-（4-chlorophenyl）-5-benzoylamide（B1）and3,5-dichloro-N-（2-chlorophenyl）-5-benzoylamide（B3）were determined by single-crystal X-ray diffraction.Hydrogen-bonding interactions in the molecules were further discussed.