Synthetic Technology Study Of Cloquintocet-mexyl And Benoxacor

Crop safeners for herbicides are a class of compounds which can protectcrops from the injury of herbicide, cloquintocet-mexyl and benoxacor are bothdeveloped and marketed by the Swiss Ciba-Geigy Company. Since it is on themarket, it caused more and more people attention. Compared with the literature,two safeners were synthesized and studied the factors affecting the reaction. Thebest synthesis was determined in this paper. Various of intermediates and targetproducts were characterized by IR and NMR.During the synthetic of cloquintocet-mexyl reaction, a new green syntheticroute with high yield, mild reaction conditions was designed in this paper, whichaccorded with green chemical industrial production. Improved route ofcloquintocet-mexyl from8-hydroxyquinoline as raw materials by substitution,hydrolysis, chlorination, esterification. Compared with the traditional method ofusing an electrolytic chlorination process for the first time to replace the originalproduction of chlorine chlorination process, the synthesis process was not onlyfriendly to environment but also higher yield over95%. The specific researchcontents and results are as follows:1. Synthesis of8-quinolinoxy acetate: Acetone as the solvent and K2CO3asacid binding agent, when the mole ratio of8-hydroxyquinoline to acid methylester is1:1.1, the mixture is stirred and refluxing for4h, yield is97.5%.2. Synthesis of8-quinoline acetic acid: Methanol as the solvent, when themole ratio of8-quinolinoxy acetate to NaOH is1:1.3, the mixture is stirred andrefluxing for5min, yield is91.8%.3. Synthesis of5-chloro-8-quinoline acetic acid: In a single-chamberelectrolytic cell, platinum as the anode and cathode, when the volume ratio of water to hydrochloric acid is25:25, the concentration of the raw material is0.2M,current intensity is0.4A, electrolysis time is2h, yield is95.0%.4. Synthesis of cloquintocet-mexyl: Concentrated H₂SO₄as catalyst, whenthe mole ratio of5-chloro-8-quinolinoxy acid to2-heptanol is1:2.0, toluene asthe solvent, refluxing got yield of80.2%.This paper studied the synthetic method of benoxacor from o-nitrophenol byacetone bromine substitution reaction, high-pressure hydrogenation closed loop,dichloroacetyl chloride substitution reaction. And reaction conditions wereoptimized to identify the optimum conditions as follows:1. Synthesis of o-nitrophenoxyacetic acetone: Acetone as the solvent andK2CO3as acid binding agent, When the mole ratio of o-nitrophenol to bromoacetone is1:1.1, the mixture is stirred and refluxing for6h, yield is72.8%.2. Synthesis of3,4-dihydro-3-methyl-2H-1,4-benzoxazine: Methanol assolvent, When the mass ratio of Pd/C to o-nitrophenoxyacetic acetone is0.1:1,the reactor temperature is60℃, reaction pressure is2MPa, the reaction wasmaintained in this state for3h, yield is98.0%.3. Synthesis of benoxacor: Toluene as solvent and triethylamine as acidbinding agent, when the mole ratio of3,4-dihydro-3-methyl-2H-1,4-benzoxazineto dichloroacetyl chloride is1:1.2, the mixture is stirred at room temperature for4h, yield is95.5%.