The Studies On Synthesis And Characters Of A Gemini Surfactant

Unlike traditional surfactants, Gemini surfactants are a novel class of surfactants which have two hydrophobic chains, two hydrophilic groups and a spacer. In recent years, many researchers pay attention to this surfactant. In this thesis, a amineoxide Gemini surfactant whose CMC(critical micelle concentration) is lower has been synthesized. First, because it can not be purified by recrystallization, the N-ethoxyl dodecylamine can be defined by coloumn chromatography. The coloumn chromatography adopts 160g silicagel whose screen mesh is 100-200 as adsorbent and the silicagel is mixed with 400g eluent and packed into the coloumn. The eluent includes 62% ethyl acetate, 28% acetone and 10% ammonia water(14 mol/L). The sample quantity is 2.5g and the eluent rate is ldrop/s(100g/h eluent). After IR, TLC and melting point testing, the sample No. 13-19 is pure N- ethoxyl dodecylamine. The thin layer chromatography adopts silicagel G which contains little sodium carboxymethyl cellulose as adsorbent and 62% ethyl acetate, 28% acetone and 10% ammonia water(14 mol/L) as developping agent. The developing distance is 12cm and the developing time is 90min. The chromogenic agent is iodine vapor and the sample is diluted to 1-2% by acetone. Then N- ethoxyl dodecylamine in normal propyl alcohol is bridged with chloroepoxy propane at 90-95℃ and the proportion is 2:1. After reaction , the normal propyl alcohol is vaporized below 80℃ and a yellow gel is obtained. The yellow gel is tested by IR and react 4h at 70-75℃ with 1.5g 27.5% hydrogen peroxide which is added at 50℃ in 15min. Then, the yellow gel is cooled to 45℃ and 4 drops fresh 25% sodium sulfite solution is added in to decompose extra hydrogen peroxide. A new yellow gel solid is obtained after 1h stirring. A pale yellow solid is obtained after defined with ethanol . There is a weak absorption in 968cm^-1 in IR spectrum of this solid and it according with amineoxide. So, this solid is regularized as amineoxide Gemini surfactant and its surface tension is tested. The CMC of this product is 0.37 mmol/L and its foam height is 185mm determined in hard water by Ross-Miles foamer. The foam height of N,N-diethoxyl dodecylamine oxide is 170mm. So, we confirm that this product has good foam ability in hard water. The freezing point has been determined out 478.