Of Alcohols and Heavy Water

Chemistry Level 4

1-propanol is reacted with pyridinium chlorochromate ( $\ce{PCC}$ ) to form $\ce A$ . $\ce A$ is then transferred to a solution of heavy water ( $\ce{D_2O}$ ) that also contains deuterated hydroxide ( $-\ce{OD}$ ) to form $\ce{B}$ .

Give your answer as the number of hydrogens ( $\ce{H}$ ) in $\ce B$ , divided by the number of deuteriums ( $\ce D$ ).

Give your answer to 2 significant figures.

$Note:$ The end product, $B$ , is not the result of aldol condensation.

David's Organic Chemistry Set

David's Physical Chemistry Set

The answer is 2.0.

1 solution

David Hontz
Jun 26, 2016

The hydrogens on the carbon $alpha$ to the carbonyl carbon of propanal are very acidic; thus they can be pulled off by $-OD$ and replaced with deuteriums from $D_3O+$ $B$ has $4 \space H$ and $2 \space D$ ; therefore $Answer \rightarrow \frac{4H}{2D} = \boxed{2.0}$

@David Hontz Can it not form an aldol product??

Ashu Dablo - 4 years, 11 months ago

Due to heavy water being used as a solvent it can be considered to be in excess; therefore, deuterium exchange becomes far more probabilistic than aldol condensation. I will specify in the problem that $B$ is not formed through aldol condensation. Thank you for bringing up your question.

David Hontz - 4 years, 11 months ago

ok, I get it.

Ashu Dablo - 4 years, 11 months ago

Of Alcohols and Heavy Water

The answer is 2.0.

1 solution

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