Final answer:
In DMSO, acidities are primarily influenced by electronic effects, with the inductive effect playing a key role. Electronic factors determine how electron-withdrawing substituents affect acidity, while steric effects are less important in this context.
Step-by-step explanation:
Acidities in DMSO are largely influenced by electronic effects, as these effects are significant in determining the strength of acids and bases in the solvent. When assessing acid strength in DMSO, electronic effects, such as the inductive effect, play a dominant role. Inductive effects occur when electronegative substituents impact the distribution of electrons in a molecule, altering its acidity.
For example, substituents that are capable of withdrawing electron density from the acidic proton through inductive effect can increase the molecule's acidity. The magnitude of this electron-withdrawing effect depends on both the nature and number of substituents, which is demonstrated by the pKa values of various acetic acid derivatives.
While steric effects can also influence reactivity, particularly in reactions where physical space within the molecule is a factor, their influence on acidity in solutions such as DMSO is typically less significant compared to electronic effects.
Steric hindrance might affect the accessibility of the acidic proton but does not have a substantial impact on the inherent strength of the acid. The inductive effect and the ability to delocalize charge are more critical for stabilizing the conjugate base and thus increasing acidity in a polar aprotic solvent like DMSO.