Question

I need help with my pre and post lab questions.

The three compounds below were spotted on a TLC plate and developed to give the TLC plate shown. Which compound corresponds to which spot? Calculate the Rf value for spot B in the TLC plate shown above. When using polarity to determine the relative rates at which organic compounds travel up the TLC plate, we are considering compounds of similar molecular weight. It should also be noted that Rf values vary with chain length when comparing molecules containing the same functional group. Would you expect 1-hexanol or 1-decanol to have a higher Rf value? Explain. Did you encounter any issues such as streaking or bleeding in any of your TCL runs? If so, explain what you observed. List the compounds used in this lab (acetaminophen, acetylsalicylic acid, and ascorbic acid) from least polar to most polar. What structural features in each do you think accounts for the polarity? An unknown mixture was found to be insoluble in a particular developing solvent. Do you think separation of this mixture will be observed on the TLC plate after development in this solvent? TLC is a common method used to monitor reactions for completion. Consider the reaction below and draw the expected TLC plate prior to the reaction, during the reaction, and after the reaction has completed. Don't worry about drawing spots for the reagents (03, DMS) or the formaldehyde product on the TLC plate.

Answer 1

3. The three comopunds shown in pictures correspond to spots A,C,B respectively.
4. Rf value of spot B= (distance travelled by spot B from initial point/total distance travelled by solvent)

Post-lab
1. Yes, hydrocarbon chain length affects the polarity of compounds, hence their Rf value on TLC plate. Out of 1-hexanol and 1-decanol, 1-decanol will have the higher Rf value since due to presence of the longer hydrocarbon chains in it, it has less polarity than 1-hexanol.
2. ---
3. Compounds such as acetaminophen, acetylsalisylic acid, and ascorbic acid have the polarity order as follows: ascorbic acid > acetylsalisylic acid > acetaminophen
The presence of ester bond, cyclic ester, hydroxyl bonds or amide bonds in the above molecules accounts for their polarity.
4. Yes, the separation of the components of the mixture is possible if their is a large polarity difference between the two components present in it.
5.