Nmr Spectra Lab Report

Again the 13C NMR spectra is consistent with the back bone or cholesterol remaining constant in the reaction. There are 27 carbon environments in the spectrum which matches that starting material. There is an evident peak at 201.25 ppm which is due to the C=O in the molecule. The carbon that had the bromine added, in chlestan-3-one this carbon is at 38.36 ppm and in this spectrum using the HSQC spectrum this peak was identified to be at 54.67 ppm which shows an increase in chemical shift. This is evident that the bromine has added as the increase in chemical shift is expected when a halogen is added to an alkane bond.

Figure 9 Thin later chromatography of cholestan-3-one (left) and 2α-bromocholestan-3-one (right).

Thin later chromotography was used to idneitfy that the reaction had go to completion. The starting material was spotted on the left, cholestan-3-one and on the right was 3. The TLC plate showed that there was a differnce between the

However, on work up the first product was not collected from the column. This resulted in further analysis on the mixture of the two products and chole-1-en-3-one. Using IR spectroscopy, the two spectrums appeared identical as expected as the shift in the double bond is the only difference between the two products. The IR spectrum shows that the cholesterol backbone is still present as there is a C-H stretch at 2926 cm-1, consistent with sp3 hybridised carbon in the molecule as well as CH2 groups as there is a stretch at 1464 cm-1. The only other significant stretch is a C=O, at 1719 cm-1 which identifies that 4 still has the ketone group produced in the oxidation of the secondary alcohol in the second step. There is not a peak at 550 cm -1 which shows that the elimination of the bromine atom has taken