Lab Report

Abstract: The epoxidation of an unknown alkene was catalyzed by the (R, R)-enantiomer of Jacobsen’s catalyst. The presence of epoxide in the final product was detected by using NMR spectroscopy and GC/MS. The (R)-enantiomer of the styrene oxide which was the final product of this project was obtained in 50% yield and an enantiomeric excess of 73.7%.

Introduction:

Epoxidation is one of the most frequent reactions that are used in organic chemistry for its wide utility. Starting with an epoxide, diols, aminoalcohols, or ethers can be synthesized. Therefore, the synthesis of epoxide plays an important role in chemistry.

In epoxidation using the Jacobsen’s catalyst, the free diamine is allowed to react with two equivalents of salicylaldehyde which is easily synthesized from phenol and chloroform via Riemer-Tiemann reaction.

6.0 grams of sodium hydroxide and 1.88 grams of phenol is dissolved in 10 ml of water. The mixture is stirred and heated to 65 ℃ using water bath. 3.0 ml of chloroform was slowly added. The mixture was refluxed for 1 hour. The mixture is then neutralized and steamed until clear liquid appear. The mixture is extract with chloroform (3*5 ml). The organic layer was dried with anhydrous sodium sulfate, and then chloroform was removed to yield salicyaldehyde (“Total Synthesis of Coumarin”).

Beside the Sharpless epoxidation or an epoxidation based on Jacobsen-type ligand, the Shi epoxidation allows the synthesis of epoxides from alkenes using fructose-derived organocatalyst with oxone as the primary oxidant.

This reaction gained the notice for it does not require the use of metal catalysts. The reaction is started with the conversion of D-fructose to the organocatayst (1) in the pH optimization (10-11). Then 3 equivalents of organocatalyst reacts with 5 equivalents of oxone and 6 equivalents of K2CO3 in MeCN/H2O to form the epoxide. The mechanism involves the formation of a dioxirane intermediate. The advantage of this procedure is that...