Purification of Cholestrol

Cholesterol

Principle:

Purification of cholesterol is based on reductive-elimination reaction. Cholesterol is a constituent of membranes and the source of steroid hormones. Purification of cholesterol starts by reduction of the Carbon Carbon double bond (c=c) with bromine to precipitate it as a solid Because of steric constraints imposed by the steroid ring structure, only cholesterol reacts with bromine to form an insoluble diaxial dibromo compound, then washing by solvent or recrystallization techniques, after that the separation of the cholesterol from any impurities and finally reaction with Zn and ether to generate the final pure cholesterol. Oxidation elimination reaction for the Zn and Bromine also will occur.

Objective:

In this experiment we will be using reductive-elimination reaction and vacuum filtration for the purification of crude cholesterol to a pure cholesterol. Purification of cholesterol is based on the bromination and debromination of the cholesterol to give us the purified cholesterol. Reduction reaction is used to form the dibromocompound and then the removal of the two bromine while the oxidation reaction by oxidizing Zn to Zn2+.

Background:

Cholesterol is a steroid compound that are present in the human and animal cells. Cholesterol can be found in the cell walls of the cells and in the myelin sheath covering nerve bundles. Cholesterol are vital for our life because they are responsible of producing steroidal hormones. Cholesterol can be isolated from contaminated natural sources with 3 to 5 % related compounds. The purification of cholesterol is unfeasible because cholesterol and its steroid impurities have the similar structure and solubility. Purification of cholesterol is based on reductive-elimination reaction.

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