Long-chain cationic gemini surfactant and preparation method thereof

The invention relates to a long-chain cationic gemini surfactant and a preparation method thereof. During preparation of a traditional gemini surfactant, when a tertiary amine hydrochloride intermediate is prepared, hydrogen chloride gas is introduced into tertiary amine, so that corrosion to equipment can be caused, and in addition, in the presence of a residual solvent, the rheological property of the gemini surfactant can be lowered. The preparation method comprises the following step: with epichlorohydrin and fatty acyl amide ethyl/propyl/butyl dimethylamine as raw materials, preparing a series of saturated and unsaturated cationic gemini surfactants with 2-hydroxy-1, 3-propylidene as a linking group, wherein a molecular structure contains an amido bond which is easy in biodegradation and hydroxyl which is easy in hydrolysis, and a hydrophobic chain is formed by alkyl chains of saturated or unsaturated long-chain fatty acids. According to the preparation method disclosed by the invention, under the condition of solvent-free alkaline catalysis, epoxyhalopropane and long-chain tertiary amine are adopted to further react to prepare a final product, so that the reaction yield is increased, the reaction process is simplified, the reaction period is shortened, and the long-chain cationic gemini surfactant is suitable for large-scale industrial production.