A Pesticide Intermediate Clean Process Verified in China

Recently a clean process for pesticide intermediate 3,5,6 trichloropyridin-2-ol sodium, which is an important intermediate for production of organophosphate pesticide chlorpyrifos, chlorpyrifos methyl and herbicide triclopyr, passed the verification organized by China Petroleum and Chemical Industry Federation.
 
According to the developer of the technique based in Shandong province, conventional process consumes higher energy and causes serious pollution while the new process uses a bi-directional synthesis method, which is of lower energy consumption and less discharge of wastes, offering a high conversion rate, high selectivity and a purity as high as above 99%.
 
The new process introduced a novel photochlorination reactor to raise the pyridine conversion rate to above 99%, with reaction product being chloropyridine and dichloropyridine, of which 2,6-dichloropyridine is proportioned to be above 60%.
 
Furthermore, the new process adopts a catalytic solvent, which quantitatively converts 2,6-dichloro pyridine into 6-chloropyridin-2-ol sodium under moderate reactions and simple separation flow sheet with yield of above 99%. Meanwhile sodium hypochlorite is used as the electrophile for the β-orientation substitution of 6-chloropyridin-2-ol sodium, which directly generates the 3,5,6 - trichloropyridn-2–ol sodium with a yield of 80%.
 
It has come to the attention of the on-site verification expert team that the process developers’ 10,000-ton demonstrative production line adopting the new process has been running stably for 2 years; the whole process operates under atmospheric reaction with simple flow sheet, which is significantly energy saving; the process water is of closed cycle, well in compliance with environmental regulation. A user’s report shows that the quality of product based upon the new process is obviously better than that of conventional process.