The following was used to carry out the experiment: 0.05g of curcumin, 10 mL of

Question

The following was used to carry out the experiment:

0.05g of curcumin, 10 mL of methanol, 0.1g of Palladium, 1.0 mL of cyclohexene

Sample 1obtained and included 15 drops of the curcumin and methanol.

Mixture was heated to reflux and then allowed the reaction to continue for 1 hour - after 30 mins, a sample of the reaction mixture was obtained (sample 2) and used for TLC plate #1, along with sample 1.

Sample 3 was the solution remaining after the reaction mixture had refluxed for an hour and had been filtered to remove all remaining Pd/C. Sample 1 and Sample 3 were used for TLC plate #2.

Both TLC plates used 58:42 Hex:EtOAc

1. Show all math calculations for the calculation of percent yield for the conversion of curcumin to tetrahydrocurcumin.

2. How did using a co-spot on both of the TLC plates that were developed help to confirm that the spot for the reduced material was not actually curcumin?

3. What does the TLC tell you about the time course of hydrogenation? What is the likelihood that all 60 minutes of the reaction was needed for a complete conversion of starting material to the end product?

4. How could the Rf Values of TLC plate #1 and #2 be increased?

5. Do you think the structure of tetrahydrocurcumin is more flexible or more rigid that the structure of curcumin and why?

Explanation / Answer

2)using a cospot on tlc plates helps in differentiating the solubilities of the products in the solvents and hence their RF values canbe used to identify the purity of the product formed.

3) tlc differentiates the products based on their solubilities in their solvents and does not explain anything about hydrogenation.

4)RF value is the distance travelled by a given component divided by the distance travelled by the solvent front. For a given system at a known temperature, it is a characteristic of the component and can be used to identify components.

using a suitable solvent increases the RF values

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