Synthesis of Piperazines. VI

Synthesis of 1,4-Diazabicyclo [2,2,2] Octane with Alkaline Earth Phosphate Catalysts

“…This and other early Houdry-Air Products patents 15−21 do not show dramatic or very impressive catalyst performance, with claimed DABCO weight yields from total feed ranging from about 8% to near 40%, a significant improvement over prior art. For example, in 1942 O. Hromatka 22,23 reported DABCO yields of around 2−3% and in the mid-1950s J. Ishigura and co-workers report "acceptable yields", 24,25 which considering the state of the art at that time was believed to be somewhere less than the 8−10% range. 13 More recent work by M. Selvaraj et al 26 claim DABCO yields in the high 80% range over mesoporous solid acids (MCM-41 derivatives) from ethanolamine and similars, while J. Armour et al 27,28 claim combined DABCO plus piperazine yields of 81− 89% from ethylenediamine over surface modified pentasil style zeolites.…”