Synthesis And Process Optimization Of Gemini Quaternary Ammonium Salt Grafted On Chitosan Oligosaccharide

Gemini quaternary ammonium salt is a strong surfactant with a wide range of uses,low toxicity,stability and good bactericidal properties.Firstly,hydroxypropyl Gemini quaternary ammonium salt and Schiff base chitosan oligosaccharide were synthesized respectively.Then,they were used as substrate for synthesizing Gemini quaternary ammonium,grafted on C₆-OH of chitosan oligosaccharide,by ethylene glycol diglycidyl ether as cross-linking agent.The optimization conditions were researched.The quaternary ammonium salt and its intermediate products were characterized by means of nuclear magnetic resonance spectrum,mass spectrometry and IR.The experimental results are summarized as follows:Firstly,hydroxypropyl Gemini quaternary ammonium salt was synthesized with dodecyldimethyl tertiary amine and epichlorohydrin as substrate.The optimal synthesis conditions were as follows:molar ratio of dodecyldimethyl tertiary amine to epichlorohydrin is 1:1.8,and the reflux time is 60 min,and the reflux tempareture is105?.Finally an epoxy monoquaternary ammonium salt with 96.2%yield was obtained.Then the reaction of synthesizing hydroxypropyl Gemini quaternary ammonium salt happened with the epoxy monoquaternary ammonium and dodecyldimethyl tertiary amine as substrate,whose molar ratio is 1:2,and the reflux time is 4 h,the tempareture is 105?.Finally,a hydroxypropyl Gemini quaternary ammonium salt with 96.17%yield was obtained.Secondly,to protect C₂-NH₂,Schiff base chitosan oligosaccharides were synthesized with chitosan oligosaccharide and benzaldehyde as substrate.The optimal conditions were that molar ratio of glucosamine monomer to benzaldehyde is 1:6,pH value is equal to 5,the tempareture is 70?and heating time is 4 h.The compound have80%condensation rate.Finally,Gemini quaternary ammonium salt grafted on Schiff base chitooligosaccharide was synthesized by Schiff base chitooligosaccharide and hydroxypropyl Gemini quaternary ammonium salt as subtrate,and ethylene glycol diglycidyl ether as cross-linking agent.The reflux reaction is carried out for 4 h at105?,pH value at 10,the mass ratio of Schiff base chitooligosaccharide to ethylene glycol diglycidyl ether to hydroxypropyl Gemini quaternary ammonium salt is 1:1.3:2.4,that is the optimal synthesis conditionsGemini quaternary ammonium salt grafted on chitosan oligosaccharide was isolated by MCI resin.The peak time interval of the eluent is 101-112 min and the yield is 66.9%.