This proposed reaction would not work. Identify what is wrong with it.
A These conditions would result in a dehydration reaction leading to an alkene product rather than the proposed aldehyde product.
B These conditions would result in the formation of an ethyl ether instead of the proposed aldehyde product.
C These conditions would result in the formation of a carboxylic acid rather than the proposed aldehyde product.
D These conditions result in the oxidation of an alcohol. However, the solvent is also an alcohol. Thus, the reagent would be oxidizing both the substrate and the solvent.
The correct answer and explanation is:
Correct Answer: D. These conditions result in the oxidation of an alcohol. However, the solvent is also an alcohol. Thus, the reagent would be oxidizing both the substrate and the solvent.
The reaction in question likely involves an alcohol being oxidized to an aldehyde. In oxidation reactions of alcohols, commonly used reagents include PCC (Pyridinium chlorochromate), Jones reagent (CrO₃/H₂SO₄), or KMnO₄, often under specific solvent conditions. Aldehydes are sensitive intermediates and can easily be over-oxidized to carboxylic acids in the presence of strong oxidizing agents or unsuitable solvents.
In this case, the key issue lies in the choice of solvent. If the solvent used in the reaction is itself an alcohol (like ethanol or methanol), and an oxidizing agent is present, the oxidizing reagent will not act selectively on the intended alcohol substrate. Instead, it will oxidize both the alcohol reactant and the alcohol solvent. This competition leads to side reactions and a decrease in the yield and purity of the desired aldehyde product.
For selective oxidation to aldehydes, it is important to use a solvent that does not participate in the oxidation process. Non-alcoholic solvents like dichloromethane (DCM) or acetonitrile are often preferred in these types of reactions to avoid this issue. When the oxidizing agent reacts with both the intended alcohol and the solvent, the reaction efficiency drops, and the outcome becomes unpredictable. Therefore, using an alcohol as a solvent in this context is chemically unsound.
This situation highlights how crucial the selection of solvents is in organic synthesis, particularly during oxidation reactions. Missteps like this can lead to low yields, undesired products, or complete reaction failure.