An effective and economic route was developed to synthesize a novel betaine zwitterionic surfactant gondoyl dimethyl amidopropyl betaine (GDAB) directly from natural fatty acid gondoic acid. The optimal processing conditions for synthesizing the intermediate and final product were probed: N,N-dimethyl-N′-gondoyl-1,3-propylenediamine was synthesized by the reaction of gondoic acid with N,N-dimethyl-1,3-propylenediamine at 160°C for 6 h, then the intermediate was reacted with sodium chloroacetate in methanol-water system (methanol/water:20% at 60°C and the product was obtained after 6h. The compounds were confirmed by IR and 1HNMR. The properties of GDAB acid solution were investigated and the results indicated that viscosity of acid solution increased with decreasing hydrochloric acid concentration and was mainly controlled by surfactant concentration and temperature. The viscosity of acid solution reached the maximum value when the concentration of hydrochloric acid was 2.28 mo L−1. <alternatives> [...] </alternatives>
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