Studies of Selenium Grignard Reagent Synthesizing Organic Selenides
|Keywords||Selenium Selenium Grignard reagent Organic selenium compounds Symmetrical diselenide Asymmetric diselenide Synthesis|
Organic selenium compounds due to the physiological activity and its important role in organic synthesis has attracted the attention of the biochemical and organic chemists for its new reagent, a new reaction physiologically active compounds has been a hot spot. The traditional method of preparation of symmetrical diselenide and asymmetric Diselenides of inadequacies: Some reagents used more expensive or difficult to obtain; some reaction must harsh conditions; some more complicated; Some low yield. Summary of the basis of previous experience, the paper discusses the new method under mild conditions by selenium Grignard reagents and halogenated hydrocarbons synthesis of symmetric the diselenide and asymmetric diselenide The main findings are as follows: 1. Preparing the conditions of each step in the symmetric phenyl Diselenides process, through a series of comparative experiments, the yield of the product under various conditions, spectral data is analyzed and compared, we arrive at the preferred conditions of the preparation of symmetrical phenyl selenides: in carbon during the synthesis of a Grignard reagent to maintain a dried nitrogen gas, carbon Grignard reagent in the reaction with selenium powder, selenium powder with bromobenzene ratio is 1:1, the time for about 1h, maintaining the temperature at 45 ° C reaction. Selenium grid Grignard reagent with a phenyl bromide, to be added magnesium selenium molar amount of 3 times, CuI 15% of the amount reactants, reaction time should be controlled at 10 hours, CUI and excess magnesium is conducive to reduce byproduct of produce and improve the yield of the target product. As for the other halogenated hydrocarbon synthesis of symmetrical organic diselenide by the steric substituent is electron or electron-withdrawing nature. 2. This method is applied to the asymmetric synthesis of organic selenium ether. The use of magnesium and organic brominated hydrocarbon selenium Grignard reagent is generated to generate the magnesium Grignard reagent, and selenium powder. Reactant and 15% CuI in 3 times the amount of magnesium in the reaction temperature at 45 ° C the reaction time is 10 hours, and can not effectively synthetic the asymmetric organic selenium ether. We have chosen bromophenyl bromo-toluene to 1 times the amount of magnesium (Mg, but the amount of) the conditions of the type of catalyst under reaction analysis and comparison of the spectral data can be seen only bromo selenides, and can not generate the asymmetric organic selenium ether. Prove our hypothesis, halogenated hydrocarbons prepared Grignard reagent is conducive to asymmetric organic diselenide. In order to increase its production rate, the key step is to adjust the amount of magnesium and the kind of catalyst.