The above reaction shows an epimeric steroid alcohol being converted by a catalyst of ruthenium and aluminum oxide to a racemic mixture of 17-estradiol 3-methyl ether and a ketone. The racemic mixture is formed by converting the beta version of the ether, where the hydroxyl group is on the top of the ring, to the alpha version of the ether, where the hydroxyl group is underneath the ring. The reaction is stopped when the amount of alpha ether is roughly equivalent to the amount of beta ether. In the notation used, the wavy line between the hydroxyl group and the ether shows that the hydroxyl group can be in either the front or the back of the molecule.
However, a ketone can be produced instead of the alpha ether when the alcohol is oxidized. Because the purpose of the reaction is to racemize the ether, this ketone is an unwanted side product. To prevent oxidation, toluene at 100 C is used as a solvent. The chemical properties of toluene slow the formation of the ketone so that at temperatures around 100 C, the yield of the racemic mixture is about 54%. Any ketone that does form can be separated from the ether by flash chromatography. This reaction is a good way to racemize the ether efficiently and inexpensively; it was traditionally synthesized at a much higher cost.
Polymers have important uses in both research and industry. Alkoxyamines are used in ATRP (atom transfer radical polymerization)-based polymerizations and can serve as efficient regulators in the preparation of polymers. In the past, the alkoxyamines were produced by the creation of radicals that are carbon-centered and were then trapped by nitroxide. This method, however, gave low yields and undesired byproducts. The reaction shown here takes place at low temperatures and in the presence of a nitroxide, utilizing an ATRP-based initiator that is treated with copper bromide. The ATRP is involved in the living radical polymerization system. Me6-tren ligand forms a catalyst complex for the reaction of the initiator with nitroxide. Equilibrium between the transfer to and from radicals and dormant species in the reaction is controlled by the Me6-tren ligand forming a complex with the Cu(II), which the free radicals can then interact with. The catalyst name Me6-tren stands for the chemical tris(2-(dimethylamino)ethyl)-amine. This is a more effective procedure for preparation that results in high yields. Discoveries such as this are important in areas such as nanotechnology.