[Synthesis]
In a 500mL three-necked flask, 55.2g of 3,4-dihydroxybenzaldehyde, 56.7g of acetaminophen, 42.6g of anhydrous sodium acetate, and 204.2g of freshly distilled acetic anhydride were added. The mixture was stirred at 80℃ for 5 hours. After cooling to room temperature, 150mL of ice water was added to the reaction solution, and the mixture was stirred until a homogeneous emulsion was formed. Upon cooling, a large amount of yellow crystals precipitated. The crystals were filtered, washed, and dried to obtain 98.0g of yellow crystals (mp 161.0℃～161.4℃), with a yield of 80.9%. 
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