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Which of the following sets of compounds cannot turn a clear orange solution of $\ce{CrO3/H2SO4}$ to a greenish opaque solution? (More than one answer is correct)
A) Ethanol
B) 2-Propanol
C) t-Butanol
D) Phenol

I think for turning a clear orange solution of $\ce{CrO3/H2SO4}$ to greenish opaque solution, the organic compound should be acidic, as $\ce{CrO3}$ turns green in basic medium. I am not sure about this.
Hence, I think A and D are the answers. Am I right?

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This particular reaction is known as the Jones oxidation, in which primary ($1^\circ$) alcohols are oxidized to aldehydes, and then again to carboxylic acids, and secondary ($2^\circ$) alcohols are oxidized to ketones.

The color change is due to the reduction of $\color{\orange}{\ce{Cr^{+6}}}$ in $\ce{H2CrO4}$ to $\ce{Cr^{+4}}$ in $\ce{H2CrO3}$. This in turn disproportionates to $\ce{Cr^{+5}}$ and $\color{\green}{\ce{Cr^{+3}}}$ in $\ce{[Cr(H2O)6]^{3+}}$, with $\ce{Cr^{+5}}$ further oxidizing the alcohols to also from $\color{\green}{\ce{Cr^{+3}}}$.

The answer to your question lies in which carbons are capable of accepting additional bonds to the alcoholic oxygen, and which are not, therefore A and B are correct.

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