MediumChemistryHigh School (11–12)Organic Compounds with Functional Groups › Aldehydes, Ketones and Carboxylic AcidsNumerical
5.31 g of benzaldehyde (106.12 g/mol) is nitrated with a mixture of concentrated nitric and…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
of benzaldehyde () is nitrated with a mixture of concentrated nitric and sulphuric acids. The main product is 3-nitrobenzaldehyde (), and the yield is . Find the amount of benzaldehyde, the mass of the product, and say why the nitro group does not go to the 4 position.
Need a reminder? The key ideaShow
An alpha hydrogen is needed for the aldol reaction (dilute base). With no alpha hydrogen, concentrated base gives the Cannizzaro reaction. A crossed aldol of two enolisable compounds gives four products. The carbonyl group is meta-directing. For the masses, use moles = mass / molar mass and the equation ratio.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. .
Step 2. Theory: . Obtained: .
Step 3. The position. The CHO group withdraws electrons by resonance. The ortho and para positions lose the most, so the attack by goes to the meta position.
Answer: and , with the nitro group in position 3.
Check. Nitration adds and removes , which is : .
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