| abstract |
Prepn. of chloropyridines of formula (I) (X,Y,Z = H or Cl provided that when X = Cl, Z must be Cl and provided that when Y = C. Z must be Cl) comprises reacting alpha-picoline with chlorine in the gas phase in the presence of water and a catalyst selected from silicates and silicate clays. A prefd. silicate is pyrophyllite. Suitable silicate clays are attapulgite, sepiolite, bentonite, saponite, hectorite and kaolinite. Pref. the mole ratio of chlorine to alpha-picoline is 3 to 10:1 and the wt. ratio of alpha-picoline to water is 1:1 to 1:20. Reaction is pref. carried out at 200-500 deg. C with a residence time of 1-30 secs. |