Synthesis And Properties Of Switchable Surfactants About Amidine Group

The surfactants bearing acetamidine group are new type of switchable surfactants which based on the trigger of CO2/N2 (or Ar). These surfactants are operable at room temperature. which have great importance in the field of environment remediation and industry. They will be studied well as one of hot spots for the present.Alkylamines, N.N-dimethylacetamide and dimethyl sulfate were used to synthesize five compounds of N'-alkyl-N,N-dimethylacetamidine through the direct method and indirect method. Then the target products, N'-alkyl-N,N-dimethylacetamidinium bicarbonates, were obtained by reacting with a large number of dry ice. The optimal conditions of direct method were studied as follows:POCl3 as the catalyst, chloroform as solvent, n(alkylamines): n(DMAC):n(POCl3)=1:2.5:0.35,65～70℃for 24 h. The yield of products was above 85%. The more pure products were synthesized by indirect method. A novel double-tailed surfactant, N,N'-didodecylacetamidinium bicarbonate, was synthesized by dimethyl sulfate, N,N-dimethylacetamide and dodecylamine as materials. What's more, better technology of intermediate N,N-diethylacetamiade dimethyl acetal was probed, with the yield increasing 18% compared with the reported. The optimum conditions were studied as follows: n(N,N-diethylacetamiade dimethyl acetal):n(dodecylamine)=1:2,70℃for 2h. Infrared Spectroscopy (IR). Mass Spectra (MS) and 1H Nuclear Magnetic Resonance (1HNMR) were used to confirm the structure of the synthetic products.Some physical and chemical properties of N'-alkyl-N.N-dimethylamidinium bicarbonates and N.N'-didodecylacetamidinium bicarbonate, such as surface tension, cmc. emulsification and demulsification function, foam activity and so on, were determined and proved to be good. The results indicated that with the alkyl chain's lengthen, cmc and ycmc would have varying degree reduction, and the surface activity enhance. The emulsification and demulsification function were better as the alkyl chain decreased and the N'-dodecyl-N.N-dimethylacetamidinium bicarbonate had the best emulsification and demulsification function. The cmc andγcmc of N.N'-didodecylacetamidinium bicarbonate were lower than single-tailed cationic surfactants, having better surface activity.