Thermal rearrangement of sulfated tallow alkanolamides

A study of reaction variables in the sulfation of tallow alkanolamides revealed that a molecular rearrangement to aminoester occurs as a result of prolonged heating in the unneutralized state. Heating sulfated isopropanolamide for 4 hr at 60 C resulted in a 60% loss of active ingredient. The sulfated diglycolamide heated at 60 C for 12 hr suffered a loss of 22% active ingredient. A 50:50 mixture of these sulfated alkanolamides heated for 12 hr at 40 C incurred no loss of active ingredient content, whereas at 60 C a 40% loss of active ingredient was observed. Thus, careful temperature control and rapid neutralization after sulfation are required to obtain sulfated alkanolamides with a high percentage of active ingredient.