2-chloro-5-pyridylaldehyde production method

The present invention discloses a 2-chloro-5-pyridylaldehyde production method. The method is characterized in that 2-chloro-5-chloromethyl pyridine, chlorine gas and inorganic acid are used as raw materials, and the method comprises the following process steps: step one, carrying out a chlorination reaction of 2-chloro-5-chloromethyl pyridine and chlorine gas, using gas chromatography to control the chlorination level, and carrying out rectification to obtain 2-chloro-5-dichloromethyl pyridine; step two, enabling 2-chloro-5-dichloromethyl pyridine obtained in the step one and inorganic acid to react, wherein the reaction temperature is 50-140 DEG C and the reaction time is 1-4 hours; and step three, enabling reaction liquor obtained in the step two and water to react to obtain a product, namely 2-chloro-5-pyridylaldehyde, wherein the reaction temperature is 0-80 DEG C. The 2-chloro-5-pyridylaldehyde production method disclosed by the present invention does not have side reactions, and the product purity is high and is 99.5% or above.