Answer the following three questions: (the currently selected answers may be wro

Question

Answer the following three questions: (the currently selected answers may be wrong)

When monitoring the reaction by TLC you see that the most benzaldehyde starting material has an Rf of 0.25. What should you do? Use a greater amount of Ethyl Acetate in relation to the amount of Hexane until the Rf is 0.5 Use a greater amount of Hexane in relation to the amount of Ethyl Acetate until the Rf is 0.5 O Rf value of 0.25 is fine as the product of this reactions the product will be more non-polar than the starting material and will travel further up the TLC plate Let the TLC run longer

Explanation / Answer

a. Use a greater amount of Ethyl Acetate in relation to the amount of Hexane until the Rf is 0.5

Since this reaction is the addition of Grignard reagent to the benzaldehyde, which results in the formation of alcohol which is more polar than the benzaldehyde. Hence to get the better separation of both the starting material (benzaldehyde) and alcohol more polar solvent (ethyl acetate) has to be used to increase the Rf value.

What proton is represented at "2.06 (br s, 1 H)"?

The correct option is Proton connected to oxygen.

Protons that are connected to heteroatoms like oxygen and nitrogen are broad in nature.

If you ran the NMR in d-DMSO and see an additional peak at 1.76ppm and 3.60ppm, what do these peaks represent?

Residue THF impurity, as THF was used as a solvent in the reaction.

The additional peak at 1.76ppm is due to CH2 group of THF, and 3.60ppm due to OCH2 group of THF

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