Synthesis And Properties Of Di-hydrophilic Betaine With Amide Group

Surfactants having two hydrophilic groups and one hydrophobic group play a important role in the recovery of oil contamination, the restoration of environment, the changes of crystallization behavior and chemical decontamination owing to their unique properties, such as excellent water solubility in hard water, strong cleaning capacity, excellent rinsing performance, good dispersion to fouling particle. A novel kind of zwitterionic surfactant, di-hydrophilic betaine with amide group, was designed and synthesized, the synthesis routes and process conditions were investigated. The structure of the product was confirmed by FT-IR and ESI-MS, the surface chemical properties of the product were measured.Lauroyl chloride was synthesized with lauric acid and thionyl chloride. The factors such as the molar ratio, reaction temperature, reaction time that influenced the reaction were investigated, the better process conditions were obtained as follows: n(thionyl chloride):n(lauric acid)=1.5:1, reaction temperature was 75℃, reaction time was 4h, the yield of lauroyl chloride exceeded 90%. N,N-bis(N,N-dimethylaminopropyl)lauramide(DATA) was synthesized with lauroyl chloride and tetramethyldipropylenetriamine. The factors such as with and without acid binding agent, adding order, the molar ratio, reaction temperature, reaction time that influenced the reaction were investigated, the better process conditions were obtained as follows: not adding acid binding agent, amine drop in lauryl chloride, n(lauryl chloride): n(tetramethyldipropylenetriamine)=1.2:1, reaction temperature was 20℃, reaction time was 8h, the yield of DATA was close to 70%. A novel kind of zwitterionic surfactant, di-hydrophilic betaine with amide group, N,N-bis(3-(dimethylcarboxymethylammonio)-propyl) lauramide(DHLB), was synthesized with DATA and sodium chloroacetate. The better reaction conditions were determined by the orthogonal experiment method as the following: n(sodium chloroacetate): n(DATA)=4.0:1, 75℃, 8h, 1/6water of water and ethanol solvent. Conversion of DATA was 88%.Surface chemical properties of DHLB were measured. The results showed that the lowest surface tension is 36.04mN/m, and critical micelle concentration is 1.07×10^-3 mol/L at 25℃. The lowest surface tension of DHLB is higher than cocoamidopropyl betaine(CAPB). The foaming property is good, is not better than CAPB, but the properties of lime soap dispersing and resistance to hard water are better than CAPB.This paper discussed various synthesis routes of N,N-bis(2-aminoalkyl) lauramide which was the intermediate to synthesize di-hydrophilic betaine with amide group. The intermediate is prepared using lower price lauric acid and diethylenetriamine, but HPLC and ESI-MS results showed that it was not possible to control conditions to obtain the primary monoamides by a simple thermal reaction. It clarified the various views of literature. Then the reaction of diethylenetriamine with ethyl trifluoroacetate results in the selective trifluoroacetylation of primary amino groups, N,N-bis(2-aminoalkyl) lauramide was prepared and confirmed by FT-IR and ESI-MS. The synthesis route is long, separation and purification of each step product is difficulty. Overall cost is not low, this route is not worth extending.