Studies On The Synthesis Of Selenides From Se Grignard Reagents

Selenium is an essential trace element for animals and humans. Organoselenium compounds are considerable interest in academia as well as in industry because of their wide involvement as key intermediates in organic synthesis and use as a food supplement. Many methods based on selenium have been developed into standard procedures in organic chemistry. Although quite a number of procedures for the synthesis of unsymmetrical organic selenides have already been published, usually, most of them require to handle the unstable reagents, or to react under strongly basic or acidic conditions via multiple steps. We have found a very simple reaction of alkyl halide with Se Grignard reagent under mild conditions to produce a series of unsymmetrical diorganyl selenides. The main results were as following:1. We have obtained better conditions to give the phenyl benzyl selenide via a series of condition experiments through analysis of the products by GC-MS. Reaction of Se with C Grignard reagent require 1h slightly reflux under the ratio of Se and bromobenzene 1:1. In the reaction of benzylchloride with Se Grignard reagent, the yield increases 5-10% in the presence of NaOH, Low temperature favor to reduce the by-products and increase the crude product's purity and yield. The appropriate excessive benzylchloride can improve the yield also.2. The application of this method to other C Grignard reagents and electrophilic reagents give the following results: active electrophilic reagents can carry through the reaction more easily, but require low temperature to reduce the by-products. While the inactive electrophilic reagents can take place the reaction at high temperature also. However, the carboxide, such as benzaldhyde and methyl chloroacetate can not react with Se Grignard reagent. The possible reason is that the carboxide cause oxidation of Grignard Reagents.