Cholesterol
ABSTRACT In this experiment, cholesterol is isolated from gallstones which consist of 80% cholesterol by weight. Finally, the isolated cholesterol is converted to 4-cholesten-3-one by a sequence of four chemical reactions. ... 2% cholesterol from gallstones, 30. ... INTRODUCTION This experiment was conducted in order to isolate cholesterol from gallstones and finally to perform a sequence of four chemical reactions on the isolated cholesterol. Cholesterol is an important class of natural products called steroids (Carleton University, 2003). ... Diagram 1 As already mentioned, gallstones by weight are made up of 80% cholesterol. In order to prepare cholesterol dibromide, the products of this reaction were used. In the first reaction, bromine is added and attacks the carbon-to-carbon double bond of cholesterol resulting in the dibromide derivative which is a solid and readily precipitates. ... The bromination step is included in order to protect the double bond from unforeseen reactions in the oxidation step in reaction 2 and to purify the cholesterol from other possible steroids in the gallstone extract (Carleton University, 2003). These other steroids do no easily undergo bromination and stay in the solution when the cholesterol dibromide precipitates. ... It involves the oxidation of cholesterol dibromide using sodium dichromate (Na2Cr2O7) while the oxidant was performed. The secondary alcohol functional group of the cholesterol is being oxidized to a ketone, creating dibromocholestanone. ... In this experiment, it was carried out at the end of the first reaction to acquire the cholesterol dibromide product. ... An IR spectrum was taken of the products cholesterol, 5-cholesten-3-one, and 4-cholesten-3-one. ... REACTION 1: PREPARATION OF CHOLESTEROL DIBROMIDE Using 20mL of ether, 3.0g of cholesterol was dissolved on a steam bath in four minutes. ... Table 1: Results from Experiment COMPOUNDS MASS (g) PERCENT YIELD (%) Cholesterol 2. ... 6 CALCULATIONS OF PERCENT YIELD: Cholesterol: Molecular Weight = 386. ... 6% Table 2: Interpretation of the IR Spectra COMPOUNDS BOND THEORETICAL VALUES EXPERIMENTAL VALUES Cholesterol O-H 3200cm-1-3600cm-1 3395 cm-1 C-H (alkane) 3000cm-1-2850cm-1 2940 cm-1 C=C (alkene) 1680cm-1-1600cm-1 1600 cm-1 5-cholesten-3-one C=O 1710cm-1-1720cm-1 C-H 3000cm-1-2850cm-1 4-cholesten-3-one C=O 1710cm-1-1720cm-1 C-H 3000cm-1-2850cm-1 C=C 1680cm-1-1600cm-1 The overall expected yield from the experiment according to the laboratory manual is: 70% (reaction 1) x 80% (reaction 4) = 56% 100 My overall yield: 30. ... 95% 100 DISCUSSION The purpose of this experiment was to isolate cholesterol from gallstones and to perform a series chemical transformations on the cholesterol and then to convert it to 4-cholesten-3-one.