Question

HELP! I need help with these couple of problems but especially question 7! Thank you!!!

5. You have run a TLC on your product from the Grignard reaction and you have discovered that your product alcohol is contaminated with the carbonyl starting material. Draw a sketch of what this TLC might look like and identify the spots that correspond to the alcohol and the carbonyl compound. Which compound do you expect to have a lower Ryvalue? Explain why that compound has the lower Ry value. 6. You now want to purify the alcohol product in Question 5. How can you separate the alcohol from the carbonyl compound in order to obtain pure alcohol? 7. What Grignard reagent and what carbonyl compound would you use to make the following alcohols? (b) () V OH HO CH2CH3 CH2OH Усны

Answer 1

Alcohols are polar than aldehyde therefore alcohol will be seen in lower Rf value in the TLC. Rf = Distance travelled by solute / Distance travelled by solvent Thus by formula alcohol will travel much less compared to aldehyde and will have lesser Rf than aldehyde Aldehyde Alcohol Mixture 6) The two compounds aldehyde and ketone can be seperated by using column chromatography using different solvent system depending on polarity of the starting materials. Secondly, another method involves, reacting the mixture with sodium bisulphite solution. Aldehyde react with bisulfite to form water soluble adduct and then alchol will be organic solvent soluble. both can be seperated as water layer and organic layer. HO EtMgBr, THF s remercie The given product can be obtained by reaction of cyclohexanone with ethyl grignard reagent to form the product. H30* MgBr HH formaldehyde on reaction with given grignard reagent form the expected product. EtMgBr, THE The given product can be obtained by reaction of benzaldehyde with ethyl grignard reagent to form the product. H307