Synthesis And Property Of High-purity Tetradecyl P-xylene Sodium Sulfonates

In order to study the structure and properties of alkylbenzene sulfonate surfactants as the degree of branching changing and the sulfonate group connecting with the xylene, a series of alkylaryl sulfonates were synthesized through several processes, involving Friedel-Crafts reaction, Grignard reaction, reduction, sulfonation, neutralization and so on. Those isomers have similar structure, carbons of same quantity, but the position of alkylaryl dissimilarity. Liner fat acid, p-xylene and alkylogen of different carbon number were used as the starting materials. The mechanism, procedures and phenomena of all the processes were described and the values of boiling range of intermediates were given. By purification, four kinds of high-purity isomers of tetradecylxylyl sodium sulfonates were finally synthesized, and the purity of the products were 95%, 98.1%, 96%, 99% respectively, determined by the two-phase titration method. The structure of the intermediates and products were identified by FT-IR and NMR. By analyzing ESI-MS, the molecular weight of the product is 404 that is the same as the theoretical value. The surface activity properties of products were studied and the values of CMC,γcmc,Γmax and Am were given. With aromatic ring shifting to the middle of the long chain the CMC increased, butγcmc decreased, Am increased, but theΓmax decreased, which showed that if the degree of branching of alkylbenzene sulfonate became high, the ability of reducing interfacial tension would be better. By measuring the interfacial tension between different surfactants and alkane, the mini alkane number was given. The interfacial tension between surfactant and the Daqing crude oil were also measured. Basing on the data of surface tension, the relation between the surfactant structure and the properties, the different ability of depressing the interfacial tension at the same condition had been illustrated theoretically.