Synthesis And Properties Of Betaine Zwitterionic Surfactants With Dual Carboxy

In recent years, Betaine zwitterionic surfactants with dual carboxyl have attracted extensive attention due to their special structures and excellent performances, such as superior resistance to hard water, outstanding synergistic effect, low irritation and preeminent coordination property. Therefore, in the industry, these compounds had been widely used as lime soap dispersants, wetting agents, and personal care products. In our present paper, six kinds of novel carboxyl betaine zwitterionic surfactants were designed and synthesized on the basis of research status, structural properties, synthesis and performance analysis of carboxyl betaine zwitterionic surfactants. Additionally, their corresponding properties and application values were carefully studied. The primary obtained results are enumerated as follows:1. Dimethyl maleate was synthesized through maleic anhydride esterification with methanol with a yield of89.0%(based on maleic anhydride). The intermediate compound2-(3-dimethylamino-propylamino)-succinic acid dimethyl ester was synthesized by Michael addition reaction of dimethyl maleate with N,N’-dimethyl-1,3-propanediamine with a yield of96.0%(based on N,N’-dimethyl-1,3-propanediamine). The total yield of the two step reaction was85.4%(based on N,N’-dimethyl-1,3-propylene amide). The structure was characterized by IR and1H-NMR. The synthetic process of2-(3-dimethylamino-propylamino)-succinic acid dimethyl ester was also studied, and the best reaction conditions were selected as follows:m (solvent)/m (DMAPA)=1, methanol was used as solvent.The reaction temperature and time are55℃and1h, respectively. The molar ratio n(DMM):n(DMAPA)=1.1:1. And some necessary experiments were conducted to verify optimal conditions.2. Six novel dual-carboxy betaine zwitterionic surfactants named CTB-8, CTB-10, CTB-12, CTB-14, CTB-16and CTB-18were synthesized by2-(3-dimethylamino-propylamino)-succinic acid dimethyl ester quaternized with 1-bromooctane,1-bromodecane,1-bromodecane,1-bromotetradecane,1-bromohexadecane or1-bromooctadecane, respectively. And then hydrolyzed by NaOH solution. The structure was confirmed by IR and1H-NMR.3. CMC and ycmc of betaine zwitterionic surfactants CTB-8, CTB-10, CTB-12, CTB-14, CTB-16and CTB-18, were determined by the methods of conductivity and dripping volume, respectively. The results showed that the CMC and yCMC decreased with the increase of the alkyl chain. Meanwhile, the emulsification were tested on six kinds of CTB-series surfactants CTB-8, CTB-10, CTB-12, CTB-14, CTB-16, CTB-18and two common surfactants CTAB, SDBS, respectively. The results of the foam properties showed that the foaming capacities of the surfactants increased with the increase of alkyl chain, but foam stability was irregular. Compared with conventional surfactants, the CTB-series surfactants emulsification properties and foam stability are better, and the foam stability of CTB-10and CTB-18is best4. The kinetic study of micellar catalysis was carried out for CTB-12and CTB-14.(1) The micellar catalysis hydrolysis of1,5-dichloro-2,4-dinitrobenzene by CBT-12;(2) Micellar catalysis mesitaldehyde and acetone aldol condensation reaction by CBT-14.The finally experimental results showed that:two kinds of surfactant micelle reactions both have good catalytic effects, The kφ has positive correlation with the concentrations of surfactant, and the equation are y=1.0038x+439.27(R2=0.926); y=0.5834x+731.64(R2=0.986), respectively. The Ks of the two kinds of surfactants micellar catalysis are437.6and1254.1, respectively. Furthermore, compared with the conventional surfactants CTAB, the micellar catalysis performance are better than that of CTAB.