Chlorantraniliprole intermediate impurity and preparation method thereof

The invention relates to the technical field of chemical synthesis, and particularly discloses a chlorantraniliprole intermediate impurity and a preparation method thereof. The structure of the impurity is shown as a formula (I) or a formula (II). The preparation method comprises the following steps: by taking ethyl 3-bromo-1-(3-chloropyridine-2-yl)-1H-pyrazole-5-formate and N, N-dimethylformamide as main raw materials, carrying out Vilsmeier-Haack formylation reaction, and then carrying out oxidation and hydrolysis reaction to obtain a new impurity as shown in a formula (I); and hydrolyzing and acidifying the new impurity as shown in the formula (I) under an alkaline condition to obtain the new impurity as shown in the formula (II). The brand-new chlorantraniliprole intermediate impurity provided by the invention can be used for contrast qualitative or quantitative use of the chlorantraniliprole intermediate impurity, and provides a research basis for monitoring the production quality of the chlorantranilipr