Halogen Exchange in Superheated Water : Getting into hot water usually isn't thought of as desirable but a growing number of researcher are suggesting just that

Getting into hot water usually isn't thought of as desirable, but a growing number of chemist and chemical engineers are suggesting just that as away to make organic synthesis more environmentally benign. Water near or above its critical point (374C, 218 atm) is attracting increased attention as a medium for organic chemistry. Water is a unique solvent; its chemical and physical properties vary considerably at high temperatures and pressure when compared to water at ambient condition. Two bromobenzenes were prepared by reaction of the corresponding 1,2-dichlorobenzene or 1,2,4-trichlorobenzene with 48% hydrobromic acid under superheated aqueous conditions. Halogen exchange in 1,2-dichlorobenzene to 1-bromo-2-chlorobenzene and 1,2-dibromobenzene has been completed under neutral and acidic conditions, using sodium bromide or hydrogen bromide as source of bromide. The response of halogen exchange in 1,2-dichlorobenzene to the presence of iron(III) chloride (FeCl3) and nickel(II) chloride (NiCl2) as catalysts was examined.