Question

Which of the following is a polar aprotic solvent?

1) Acetone
2) DMF
3) I-
4) -SH
5) -CN

Answer 1

Acetone ((CH3)2C=O) and DMF ((CH3)2NCHO) are examples of polar aprotic solvents. They do not have an acidic proton and are useful in SN2 reactions. I-, -SH, and -CN are not classified as solvents.

Step-by-step explanation:

The polar aprotic solvents are characterized by their inability to donate protons (hydrogen atoms) in chemical reactions. They are different from polar protic solvents, which do have acidic protons, like water (H2O) and methanol (CH3OH). Given the options, acetone ((CH3)2C=O) and dimethylformamide (DMF, (CH3)2NCHO) are examples of polar aprotic solvents. They have a center of positive polarity surrounded by bulky groups that do not provide an acidic proton. Conversely, I- (iodide), -SH (thiol groups), and -CN (cyano groups) are not solvents, but rather individual ions or functional groups.

A substance like acetonitrile (H3CCN) is also considered a polar aprotic solvent. It can dissolve salts as well as organic compounds, which is why it's found in products such as paint. Polar aprotic solvents like acetone and DMF are particularly useful in SN2 reactions, as they allow nucleophiles to freely approach electrophilic carbon atoms in the substrate.