1.cinnamaldehyde; 2. 2-methoxycinnamaldehyde; 3. cinnamyl alcohol; 4. cinnamyl a
ID: 487998 • Letter: 1
Question
1.cinnamaldehyde;
2. 2-methoxycinnamaldehyde;
3. cinnamyl alcohol;
4. cinnamyl acetate;
5. cinnamic acid;
6. coumarin;
7. eugenol
The flavour components of commercial cinnamon samples have been analysed by normal phase TLC of acetonitrile solvent extracts using a hexane, chloroform and triethylamine (90 + 6 + 4 % by volume) mobile phase on pre-developed silica gel plates.
(1) Given the nature of the stationary and mobile phases, what is the primary separation mechanism involved in the TLC separation?
(2) Based on the mechanism involved, predict the elution order of the flavour components shown below. Explain the basis for your predicted elution order.
(3) What would be a suitable detection method for visualizing the developed TLC plates for this sample?
(4) Why would triethylamine be added to the solvent mixture for this separation?
(5) “Pre-development” in this case means the blank plates were run with 92%v hexane + 8%v triethylamine and dried prior to application of the samples. Why might this be important?
Explanation / Answer
Separating components using tlc
(1) The stationary phase here is silica gel. The compounds get separated by partition principle wherein the more soluble component partitions well in the like solvent system and then unlike component stays behind on the surface.
(2) the elution order would be thus, (first to elute) : cinnamyl acetate > coumarin > 2-methoxycinnamaldehyde > cinnamaldehyde > cinnamyl alcohol > eugenol (elutes at the end)
(3) Suitable detection method here would be UV-Vis as all the compounds are conjugated.
(4) Triethylamine is added to reduce the acidity of the staionary phase for better separation of components.
(5) Blank run is carried out to ensure that no components are present on the plate and/or solvent which might interfere with the result,
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.