Experiment 9-Natural Products PDF

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Natural Products Isolation and Alkenes Introduction: The objective of this experiment was to exhibit the method of steam distillation in order to demonstrate the extraction of essential oils. Then thin-layer chromatography, FTIR spectroscopy, a bromine test, and a ferric chloride test will be performed in order to characterize the unknown compound chosen. Steam distillation is a process used to extract essential oils from plant material, in this case the unknown spice. The unknown spice and water are distilled and boiled, then the oil is extracted from the solvent and the tests are conducted. Summary of Experiment: For this experiment, the spice labeled unknown 6 was chosen. 4.008 grams of unknown 6 was measured out. The odor was sweet, strong, and sharp. Techniques including gas chromatography, FTIR spectroscopy, TLC, bromine testing and ferric chloride testing were incorporated in order to determine the essential oil and unknown spice. Below is a table showing the recorded data and observations. Techniques Used TLC

Ferric Chloride Test

Bromine Test

Identified Essential Oil Identified Spice

Results Rf values of natural product: 1st spot Rf= 1.5/7= 0.214 2nd spot Rf= 4.5/7= 0.643 Rf values of trans-a: 1st spot Rf= 1.5/7= 0.214 2nd spot Rf= 4.5/7= 0.643 Start color: colorless After adding 5% FeCl3: color changed to deep yellow After 2nd drop: color stayed deep yellow Results: negative (therefore cannot be a phenol)  cannot contain eugenol Bromine + cyclohexane- negative test Bromine + cyclohexene= positive test (double bond) Bromine + natural product= positive test (double bond) Trans-anethole Anise

Once the essential oil was extracted, gas chromatography was performed, the IR spectrum was taken and multiple peaks between 1490 cm -1-1000 cm-1 and 900 cm-1-700 cm-1. This identifies the aromatic ring and the possible carbonyl group. The TLC test showed two spots of the natural product whose Rf values of 0.214 and 0.643 corresponded with the 2 spots of trans-anethol standard spotted on the TLC plate. These values were calculated using the formula: Rf=(d1/ds).The negative ferric chloride test helped deduced that the essential oil could not be a phenol, therefore eliminating the possibility of it being eugenol. The positive bromine test helped confirm that there were double bonds in the essential oil. From the IR spectrum and the tests conducted, it can be confirmed that the essential oil obtained is transanethole. It can also be determined by comparing the IR spectrum of this essential oil to the IR spectrums found in the hallway that the unknown spice can be identified as anise.

The percent yield was calculated after the solvent was dried over 1.001 grams of anhydrous Na2SO4 and the essential oil was ultimately obtained. Initially starting with 4.008 grams of the unknown spice, the content of the round-bottom flash was weighed at 0.697 grams. The percent yield is calculated below. Percent Yield=

0.697 g actual yield ∗100 %= ∗100 %=17.4 % theoretical yield 4.008 g

Possible source of errors and probable solution: A possible source of error could be water contamination of the essential oil when conducting the gas chromatography and obtaining the IR spectrum. This error could skew the results of the IR spectrum and show inaccurate peaks. Another possible source of error could be not allowing the dichloromethane to properly evaporate. This could lead to the mixture of the essential oil with dichloromethane. A probable solution to this error would be to wait the properly allotted time in order to remove all dichloromethane. Discussion of Results: The identified Rf values, IR spectrum peaks, and classification tests conducted successfully helped to determine the essential oil obtained from the unknown spice. The R f values of the natural product and trans-anethol standard helped determine the essential oil as trans-anethol, the classification tests helped eliminate the other possible essential oils, and the IR spectrum peaks helped determine the unknown spice as anise. From the data and observations, it can be concluded that experiment successfully achieved the objective of using steam distillation and the other observed techniques to characterize unknown spice 6 and its obtained essential oil....