page 31-35 Flashcards
What type of anions are solvated more strongly in polar protic solvents?
A: Smaller, more electronegative anions.
How does strong solvation affect nucleophilicity?
A: It shields the anion, making it less reactive.
In polar protic solvents, how does nucleophilicity change down a column of the periodic table?
A: Nucleophilicity increases as the size of the anion increases.
What is the relationship between nucleophilicity and basicity in polar protic solvents?
A: They are opposite; smaller anions are better bases but poorer nucleophiles.
Which halide ion is the strongest nucleophile in polar protic solvents?
A: I⁻ (iodide ion).
Why is I⁻ a better nucleophile than F⁻ in polar protic solvents?
A: I⁻ is less strongly solvated due to its larger size, making it more reactive.
Which halide ion is the weakest nucleophile in polar protic solvents?
A: F⁻ (fluoride ion).
What is the primary role of polar protic solvents in substitution reactions?
A: To solvate and stabilize ions, influencing nucleophilicity.
How does the size of an anion affect its solvation?
A: Larger anions are less strongly solvated, making them better nucleophiles.
What is the trend in nucleophilicity for halides (F⁻, Cl⁻, Br⁻, I⁻) in polar protic solvents?
A: I⁻ > Br⁻ > Cl⁻ > F⁻.
What does strong solvation of F⁻ in water result in?
A: Reduced nucleophilicity due to shielding by water molecules.
In polar protic solvents, why does basicity not directly correlate with nucleophilicity?
A: Solvent interactions reduce the reactivity of smaller, stronger bases.
What effect does the electronegativity of an anion have in polar protic solvents?
A: Higher electronegativity leads to stronger solvation, reducing nucleophilicity.
Which property of solvents makes them “polar protic”?
A: The ability to form hydrogen bonds.
How does methanol (CH₃OH) compare to water (H₂O) in solvating anions?
A: Methanol solvates less strongly than water due to fewer hydrogen bonding interactions.
What are polar aprotic solvents incapable of?
A: Hydrogen bonding.
What type of interactions do polar aprotic solvents exhibit?
A: Dipole-dipole interactions.
Name a common polar aprotic solvent with the formula CH₃COCH₃.
A: Acetone.
What is the common abbreviation for tetrahydrofuran?
A: THF.
Which polar aprotic solvent is represented by the structure HCON(CH₃)₂?
A: Dimethylformamide (DMF).
Why are polar aprotic solvents commonly used in substitution reactions?
A: They do not solvate nucleophiles strongly, allowing them to remain reactive.
What differentiates polar aprotic solvents from polar protic solvents?
A: Polar aprotic solvents lack O-H or N-H bonds and cannot form hydrogen bonds.
Which solvent among the following is polar aprotic: water, acetone, ethanol?
A: Acetone.
How do polar aprotic solvents interact with cations?
A: They stabilize cations through dipole-dipole interactions.