Synthesis of Gemini Surfactants Disodium Dialkyl Naphthalene Di-Sulfonates

In this paper, a series of variable hydrophobic chain-length disodium dialkyl naphthalene disulfonate (DDND) surfactants have been synthesized from cheap raw materials naphthalene, α-olefins and chlorosulfonic acid. The alkylation of naphthalene with long-chain α-olefins was performed in the presence of acidic catalysts. It’ s found that more than 95% conversion of olefins and about 90% selectivity of desired di-alkyl naphthalene (DAN) can be obtained. The as-synthesized DAN intermediates were further sulfonated by using chlorosulfonic acid as sulfonating agent and neutralized by NaOH, and thus the target products DDND were obtained. The purities of DDND were determined by HPLC and the structure of DDND was characterized by IR, UV and ESI-MS. The surface tensions of DDND aqueous solutions were measured with a ring method. It’s found that the novel surfactants possess high capacity and efficiency of lowering both surface tension and cmc.