20. Discuss what you would observe after elution and visualization of a TLC
plate having made the following mistakes in carrying out the analysis.
a. The solvent level in the developing jar was higher
than the original line on which the samples were
b. Too much sample was applied to the TLC plate.
14. Suggest a suitable mechanism for the reaction of 9-fIuorenone with 2,4-
dinitrophenylhydrazine to form the corresponding
2 ,4-d initrophenylhyd razone.
15. There are actually two isomeric 2,4-dinitrophenylhydrazones of 2-
pentanone. Draw the structures of these isomers.
8. When 1-octene is treated with NBS, three monobromo straight-chain
alkenes having molecular formula C9H17Br are Isolated from the reaction
mixture. Identify these compounds and give each a suitable name.
9. Benzyl bromide (C6HsCH2Br) can be prepared by treating toluene with
NBS in the presence of a peroxide initiator. Suggest a suitable mechanism
to account for this reaction.
It includes coneptual organic chemistry problems answered in a very simple way
4 questions (L6) Lab
13. What chemical tests might be used to distinguish between pentanal and 2-
pentanone; between benzyl alcohol and diphenylmethanol?
17. The haloform reaction using 12 and NaOH is referred to as the "iodoform"
test for methyl ketones. The test also gives positive results for compounds
containing the -CH(OH)CH3 group. This results from the oxidation of the
alcohol to the methyl ketone in the first stage. Write a balanced equation
for the conversion of C6H5CHOHCH3 to the methyl ketone in the presence
of 12 and NaOH. Identify which species is being oxidized and which is
18. If you were carrying out an industrial scale synthesis in which one step
involved a haloform reaction to convert a methyl ketone into the
corresponding acid having one less carbon atom, would you use NaOH
and C12, NaOH and Br2, or NaOH and 12 reagent? Give reasons for your
19. Over the years the two isomers of azobenzene have been designated by
various terms: cis-trans, syn-anti, and E-Z. Using each set of terms,
assign them to the isomers of azobenzene.