Preparation Of Hydroxypropyl-β-cyciodextrin And Study On Its Inclusion Complex With Allethrin

Hydroxypropyl-β-cyclodextrin (HPCD) is a kind of hydroxyl alkyl derivatives ofβ–cyclodextrin. It has not only a special cavity of β–cyclodextrin, but also the advantages ofhigh solubility, selectivity and stability with introduction of hydroxypropyl. In recent years,HPCD has been widely used in the pharmaceutical, food and other fields.However, the preparation process of HPCD is not mature at present. In this paper, theway of preparing HPCD using β-cyclodextrin was improved. And the preparation process ofthe inclusion complex with the insecticide allethrin and HPCD was studied. Then propertiesand structure of the inclusion complex were discussed. And the application of HPCD wasexpanded in the field of pesticide. The main contents and research results were as follows:(1) The preparation of HPCD coordinating for better degree of substitution (DS) andyield was optimized by single factor experiments and orthogonal experiments. The productionof HPCD (DS:5.12;yield:82.3%) was obtained. The detailed process conditions weredescribed as: the reaction temperature was35℃, reaction time was20h, the concentration ofNaOH was5%. And the results were proved by thin layer chromatography. With differentdosages of epoxy propane, four kinds of HPCD products with different DS were produced bythe optimization process conditions. And the physicochemical properties of HPCD productswere tested. The results showed that they had good DS and yield, high degree of whiteness,low ash content, suitable moisture content and better solubility. All the indexes were reachedthe need for further study.(2) The preparation process of the inclusion complex of HPCD and allethrin wasoptimized by single experiment and orthogonal experiment, and the parameters for processconditions were as follows: using the HPCD production with DS–5.12, reaction temperaturewas50℃, time was8h, stirring rate was300r/min, and molar ratio was1∶2. Theconditions were ensured as the best experimental conditions by parallel preparation of threeclasses of inclusion complex under the experimental conditions, with SD–1.2%, the averageencapsulating yield of allethrin–91.3%.(3) The formation of inclusion complexes of HPCD and allethrin were proved by DSC,TGA and IR. The thermal stability and toxicity of the inclusion complex was studied, and theresults showed that formation of the inclusion complex was favorable for improving thestability of allethrin in the environment, and the inclusion compound had good slow-releaseeffect. The toxicity of inclusion complex would not be weakened and the persistence ofpesticide effect was increased due to the formation of inclusion complexes.(4) The molecular structure of inclusion complex was predicted using NMR technique.The result showed that the configuration of allethrin/HPCD complex was that the pentagonring of allethrin entered the cavity of HPCD,and the barycenter of the pentagon ring locatedaround the H-5of HPCD cavity. This result was consistent with the results of Hyperchem8.0.