Study On The Synthesis Of Gemini Surfactants And The Surfactants Application In Aldol Condensation Reactions

In this paper, the condensations between a series of nitrogen aromatic hetrocyclic compounds and the corresponding ketones in micellar media based on various surfactants were studied. The use of water as the reaction medium makes the process environmentally benign.18-4-18and18-3(OH)-18were synthesized with the N,N-Dimethyl-n-octadecylamine. The CMCs were respectively9.68×10-5mol/L,3.76×10-5mol/L, less than conventional surfactants.4-(3-indole)-3-olefin-2-butanone (A) was prepared from3-indole formaldehyde and acetone;1-(2-pyridyl)-3-phenyl-2-propylene (B) was prepared from2-acetyl pyridine and benzaldehyde;1-(2-pyrrole)-3-phenyl-2-propylene (C) was prepared from2-acetyl pyrrole and benzaldehyde;1-(3-pyridyl)-3-phenyl-2-propylene (D) was prepared from3-acetyl pyridine and benzaldehyde. It was found that18-4-18can significantly improve the yields of compounds A, B and C. Under the optimized conditions, the yields of the compounds above were41.3%,83.3%,97.4%. Nevertheless, in the presence of18-4-18or18-3(OH)-18, yields of compound D were reduced to18.4%,50.0%.The reactions of2-acetyl pyridine and2-acetyl pyrrole based on the18-4-18was particularly efficient in giving the highest yields. It’s attributed to the solubilization and OH--carrying capability of the cationic surfactants. The addition of18-4-18has better effects on the reaction of2-acetyl pyrrole than that of2-acetyl pyridine. It is due to that the electron donating aromatic rings elevate the catalytic performance; The different effect of18-4-18on2-acetyl pyridine and3-acetyl pyridine is because of the higher electrone-gativity of meta-position, which prominently activates the target product and facilitates its concentration in the micelle, and then gives rise to the dimerization reaction; In contrast with the effects of18-4-18and18-3(OH)-18, the hydroxyl in18-3(OH)-18inhibits the OH--carrying capability, which is beneficial for the condensation of3-acetyl pyridine while reducing the catalytic performance in the condensation of2-acetyl pyridine.