Study On Synthesis And Properties Of Phosphate Gemini Surfactants

Gemini surfactants is a name assigned to a family of synthetic amphiphiles possessing, in sequence, a long hydrocarbon chain, an ionic group, a spacer, a second ionic group, and another hydrocarbon tail. Recently geminis had received much attention and interest in many countries, because their better physicochemical properties and utilities than conventional surfactants'. Many articles about anionic gemini surfactants had reported. My work is focus on phosphate gemini surfactants and find a rule due to carbon atom' sum of gemini surfactant's hydrophobic tail.Spacer-inserting was used in the synthesis of phosphate gemini surfactants in this thesis. First it is the synthesis of alkyl phosphate. Conventionally synthesis of alkyl phosphate have three ways: P2O5,PCl3,POCl3. Above mentioned ways is always company with by-product: diphosphate and triphosphate. So we take pyrophosphoric acid as phosphoryl agent. Combine alkanol and toluene in a flask. Add pyrophosphoric acid to the solution. After three days stirring, add ether to the reaction mixture and wash it with water. Gently swirl the ether layer with water containing NaOH, being careful to avoid emulsion formation as much as possible. Collect the aqueous phase, and add more water to the ether portion to reclaim additional product. Acidify the combined water layers with concentrated HCl to form a white precipitate. Take up this precipitate in ether, and extract the water layer further with three portions of ether. Combine the ether extracts, and remove the ether to produce a waxy white solid, alkyl phosphate, which can be purified by crystallization from hexane to produce shiny white crystals. Monophosphate of product is above to 90%, that is tested by automatic electric potential titrimeter.Second, dissolve alkyl phosphate in 25% tetramethylammonium hydroxide in methanol plus another dry, freshly distilled methanol. Concentrate the solution under reduced pressure to produce a semisolid material to be dissolved in acetonitrile containing α,α'-dichloro-p-xylene. Boil the mixture, now containing a white precipitate, under reflux for 16h. Remove the solvent under vacuum, and dissolve the resulting white residue in water. Acidify with concentrated HCl to form a white solid. Wash this solid with water and dry in vacuo overnight to obtain crude alkyl phosphate. Recrystallize the product to yield a pure fluffy white solid. Spacer-inserting reaction is a nucleophilic substitution reaction. Adding tetramethylammonium hydroxide can make reaction mixture maintain certain alkalinity, that is benefit to complete nucleophilic substitution reaction.As a result, all the phosphate gemini surfactants had been identified to be the respected structure by chemical analysis, chemical calculate and IR. Research of this novel compounds was the first in domestic, and report about this study had not been found.All the phosphate gemini surfactants have more surface activity than conventional surfactants. Surface activity is up followed by from 8-carbon to 12-carbon of hydrocarbon chain. But 16-carbon hydrocarbon gemini surfactants' surface activity is down much. Because the long hydrocarbon chain disturb reciprocally, which make it low self-assembling. Thereby it influence surface absorption.