A groundbreaking green chemistry approach has emerged for synthesizing chloroethyne, an essential ingredient in high-efficiency pyrethroid insecticides widely used in household products like fly coils to combat mosquitoes, flies, and cockroaches. Traditional manufacturing methods face significant challenges, such as uncontrolled exothermic reactions during chlorination that generate excessive isomers and high-boiling impurities. This necessitates costly repeated distillations and produces acidic wastewater laden with metal ions (e.g., from Lewis acids), which contaminates ecosystems and often leaves residues in the final product, compromising quality and safety. The need for sustainable, cost-effective solutions in agrochemical industries is urgent, as global demand for low-toxicity pesticides surges amidst tightening environmental regulations—this innovation addresses that gap by redefining the synthesis pathway to eliminate harmful byproducts.

The novel synthesis centers on a recyclable immobilized catalyst system, dramatically simplifying production. Key materials include a catalyst like tin tetrachloride immobilized onto coconut-shell activated carbon support, with ethanol as the preferred low-boiling-point solvent. The process unfolds in two main stages: first, catalyst preparation involves blending catalyst, support, and solvent in specific proportions (e.g., 1:4:6), followed by a 2-hour ethanol reflux at 105°C for activation; second, the catalyzed substitution reaction occurs under optimized conditions. Here, 6,6-dimethyl-4-yn-2-heptenyl methyl ether reacts with acetyl chloride at near-freezing temperatures (0–5°C) for 3–6 hours, leading to efficient conversion without the harsh side reactions plaguing conventional approaches. This design leverages temperature control and solid-phase catalysis to suppress unwanted isomer formation, achieving purities as high as 97.2% with minimal trans-isomer content under 0.7%.

Operational enhancements make this process exceptionally efficient and environmentally benign. After substitution, the mixture undergoes straightforward filtration to separate the catalyst—retrieved and reactivated for up to three reuse cycles—before washing with a 20% sodium bicarbonate solution to ensure phase separation. Oil–water partitioning is optimized to yield a transparent organic layer free of suspensions, which then enters a low-energy distillation step at 40°C under -0.085 MPa vacuum, recovering both the target intermediate and the co-product, ethyl acetate. This integrated workflow drastically reduces the need for energy-intensive purifications and trims waste volumes. For instance, pilot runs demonstrate raw yields up to 91% with catalyst reuse, versus older methods plagued by poor selectivity and recurring effluent treatments. Moreover, the catalyst immobilization prevents leaching into products or wastewater, cutting metal ion pollution that once rendered outputs unsuitable for insecticide formulations—a win for both manufacturing economics and planetary health as industries shift toward circular processes.

Performance data from validated implementations underscore the advantages. In one example setup (analyzed via gas chromatography), the immobilized system achieved product purities consistently above 96% with yields over 90%, while the reused catalyst maintained effectiveness through three batches, showing only a marginal efficiency dip by the third cycle (e.g., yield falling to 89% from an initial 91%). Such repeated activations at 105°C not only lower costs by conserving expensive inputs but also demonstrate robust stability against degradation. Crucially, the environmental footprint shrinks: by eliminating acidic waste sludge and minimizing hydrolytic contaminants, production residues fall well within discharge standards. This contrasts starkly with legacy techniques that relied on hazardous Lewis acids like aluminum chloride, which often required complex neutralizations and generated stubborn effluent, leading to higher operational burdens and regulatory risks. Overall, the innovation delivers a commercially scalable route that enhances process safety, as reactions proceed predictably without runaway thermal risks, and paves the way for greener insecticide manufacturing worldwide.

Adoption of this green synthesis process promises to reshape the insecticide supply chain, offering producers a tangible route to sustainability targets without sacrificing output quality. By enabling high-selectivity, low-waste outputs at ambient pressures and temperatures—key for scaling—the technology accelerates the transition toward bio-sourced chemicals, aligning with circular economy principles. Industries can now integrate these advances to slash production expenses by up to 20%, per economic forecasts, while meeting eco-certifications and lowering risks of soil and water contamination. Looking ahead, this method serves as a benchmark for other fine-chemical syntheses needing catalyst recyclability and waste reduction, highlighting the broader shift where advanced immobilization techniques become central to eco-friendly industrial chemistry in the pesticide and pharmaceutical sectors.