Synthesis And Derivation Of Alpha Long-chain Alkyl-N,N-dimethylglycine

Excellent surfactants can provide environmentally friendly, safe and finefunctional additives for chemical industry. The development in surfactants derivedfrom natural sources such as natural fatty acids. In this paper, a high-yield, low-costsynthesis route of lpha long-chain alkyl-N,N-dimethylglycine was developed，whichbased on alpha-chloro fatty acid (derived from natural fatty acid) as raw materials.After optimizing the aqueous phase hot-press synthetic technology and solvent-freehot-press synthetic technology of lpha-dodecyl-N,N-dimethylglycine (DDMG), theyield of DDMG can reach90%, respectively. In addition, lpha-tetradecyl-N,N-dime-thylglycine (TDMG) and lpha-hexadecyl-N,N-dimethylglycine(HDMG) weresynthesized with solvent-free hot-press synthetic technology. A novel amine oxidesurfactant containing carboxyl group, namely, alpha-carboxyl undecyl dimethylamineoxide (CUAO) was synthesized by oxidation of DDMG with hydrogen peroxide. Thesurface tension, foaming performance and emulsifying ability of CUAO were studied.The main research conclusions were as follows:The structure of DDMG was confirmed by IR, ESI-MS and1HNMR. And theeffects of reaction temperature, ratio of raw materials, reaction time and reactionpromoters on the yield of DDMG for aqueous phase hot-press technology wereinvestigated. The results show that KOH and NaOH can promote the yield of DDMG,while the effect of KI to the reaction is not obvious. The yield of DDMG can reach93%under the following conditions: n(DMA): n(α-CDA): n(NaOH)=4:1:1, thereaction lasted14h under100oC.The solvent-free hot-press synthesis technology was employed to synthesizeDDMG, TDMG and HDMG using alpha-chloro fatty acid and dimethylamine as rawmaterials. The structures of the three surfactants were identified by IR, ESI-MS and1HNMR. The effects of reaction temperature, ratio of raw materials, reaction time andreaction promoters on the yield of DDMG were investigated. The results reveal thatthe optimum conditions were as follows: n(DMA): n(α-CDA): n(NaOH)=10:1:1, thereaction lasted12h under100oC. Under the optimum conditions, the yield of DDMGcan reach91%.Alpha-carboxyl undecyl amine oxide(CUAO) was prepared by oxidation ofDDMG with hydrogen peroxide, and the structure of CUAO was confirmed by IR,MS and1HNMR. The surface tension, foaming performance and emulsifying abilityof CUAO were measured. The results indicate that CUAO have better surface activity,foaming performance and emulsifying ability in acidic condition than that in alkaline condition, and the foaming performance and emulsifying ability of CUAO in acidiccondition were better than dodecyldimethylamine oxide(DDAO), sodium dodecylsulfate(SDS) and Lauryl alkylbenzene sulfonates(LAS).