Coagulation technology has been used since 1970 in northern Chile for removing arsenic from drinking-water. This experience suggests that coagulation is an effective technology for the removal of arsenic. It is currently possible to reduce arsenic from 400 microg/L to 10 microg/L at a rate of 500 L/sec, assuming pH, oxidizing and coagulation agents are strictly controlled. The Chilean experienc...

The reactions of sec-aminodienyl esters 3 with crotonaldehyde (4) afforded N-alkyl 3-[2-(methoxycarbonyl)ethenyl]-4-methyl-1,4-dihydropyridines 5, providing a new azaelectrocyclization reaction.

The reactions of sec-aminodienyl esters 3 with acetylacetone (4) afforded N-alkyl 3-acetyl-4-methoxycarbonylmethyl-2-methyl-1,4-dihydropyridines 5 and enamines 6, providing a new azaelectrocyclization reaction.