Diethyl chloromaleate is a highly reactive α,β-unsaturated ester intermediate with wide applications in organic synthesis, pharmaceutical and agrochemical fields. Its molecular structure contains electrophilic double bond and active chlorine atom, enabling it to undergo nucleophilic substitution, addition and cyclization reactions efficiently. In pharmaceutical synthesis, it is a key building block for constructing heterocyclic skeletons such as pyrroles, furans and thiophenes, used in the preparation of anti-inflammatory, analgesic and anti-viral drug candidates. In agrochemical industry, it serves as an important intermediate for synthesizing herbicides, fungicides and plant growth regulators, contributing to the development of high-efficiency and low-toxicity pesticides. Additionally, it is widely used in fine chemical synthesis for preparing functional esters, polymer monomers and organic reagents. Its unique reactivity makes it an indispensable raw material in early-stage drug discovery and custom synthesis of fine chemicals.

GHS Classification: H315 (Causes skin irritation), H319 (Causes serious eye irritation), H335 (May cause respiratory irritation). Signal Word: Warning. Acute oral LD50 in rats is >2000 mg/kg, indicating low acute toxicity. Direct skin contact may cause redness, itching and mild dermatitis; prolonged contact should be avoided. Eye contact can lead to severe irritation, lacrimation and conjunctival inflammation, requiring immediate flushing with plenty of clean water for at least 15 minutes and medical attention if necessary. Inhalation of vapor or mist may irritate the respiratory tract, causing cough, sore throat and discomfort. No definite evidence of carcinogenicity, mutagenicity or reproductive toxicity has been found in current toxicological studies. It is slightly harmful to aquatic organisms, so it should not be discharged into water bodies or soil arbitrarily. Operations must be carried out in a well-ventilated fume hood; operators should wear nitrile gloves, splash-proof goggles and organic vapor respirators. Store separately from strong oxidants, strong bases and food chemicals; waste should be disposed of in accordance with local hazardous waste regulations.