Preparation Of Degradable Sodium Sulfoitaconate Diesters Anionic Surfactants

On the basis of the relevant literature, a series of sodium sulfoitaconate diesters anionic surfactants were synthesized using itaconic acid (IA) as the raw material, successively followed by sulfonation and esterification reaction process. The preparation rule, molecular structure and surface activity of the resultant surfactants were studied to obtain a new class of environmentally friendly anionic surfactants. The wide application of itaconic acid could reduce the dependence of surfactant industry on the fossil resource and alleviate the greenhouse effect.Firstly, the sulfoitaconic acid was prepared using itaconic acid and sodium bisulfite as the raw materials, and hydroquinone as the inhibitor, through the sulfonation reaction; Afterwards, the esterification reaction of n-octanol and sulfoitaconic acid (SIA) with p-toluenesulfonic acid as the catalyst to obtain sodium n-octyl sulfoitaconate diesters (SSID-8) was carried out. The optimum conditions determined by the single factor experiments and orthogonal experiments were as follows:the amount of catalyst was 4.0 wt% relative to sulfoitaconic acid, the reaction temperature was 140℃ the molar ratio of n-octanol to SIA 2.05:1, and the reaction time 4.0 h; And then, the chemical structures of the prepared surfactants were characterized by FTIR and 1H NMR.Secondly, according to the synthesis process of sodium n-octyl sulfoitaconate diesters (SSID-8), a series of sodium n-alkyl sulfoitaconate diesters anionic surfactants with different carbon chain length, abbreviated as SSID-n (where n= 8,12,14,16, or 18) were synthesized by changing the number of carbon atoms of the fatty alcohol. The optimum reaction conditions and molecular structure of the surfactants above mentioned were confirmed.Thirdly, the surface tension, the critical micelle concentration (CMC), the Krafft point, the emulsifying properties, the foam properties, the lime soap dispersing power, the wetting properties and the biodegradability of the SSID-n were analyzed and tested. The results showed that sodium sulfoitaconate diesters anionic surfactants had low CMC and Krafft point, excellent wetting properties and good emulsifying power, foaming and biodegradability, the lowest surface tension could up to 25.05 mN/m. Therefore, these surfactants may be used as detergents, wetting agents, foaming agents, emulsifier, and solubilizer.