Ch. 8 - Elimination ReactionsSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Solution: Dimethylformamide (DMF), HCON(CH3)2, is an example of a polar aprotic solvent, aprotic meaning it has no hydrogen atoms attached to highly electronegative atoms. (c) DMF, when used as the reaction solvent, greatly enhances the reactivity of nucleophiles (e.g., CN- from sodium cyanide) in reactions like this:  NaCN + CH3CH2Br → CH3CH2C≡N + NaBr Suggest an explanation for this effect of DMF on the basis of Lewis acid–base considerations. (Hint: Although water or an alcohol solvates both cations and anions, DMF is only effective in solvating cations.) 

Problem

Dimethylformamide (DMF), HCON(CH3)2, is an example of a polar aprotic solvent, aprotic meaning it has no hydrogen atoms attached to highly electronegative atoms.

(c) DMF, when used as the reaction solvent, greatly enhances the reactivity of nucleophiles (e.g., CN- from sodium cyanide) in reactions like this: 

NaCN + CH3CH2Br → CH3CH2C≡N + NaBr

Suggest an explanation for this effect of DMF on the basis of Lewis acid–base considerations. (Hint: Although water or an alcohol solvates both cations and anions, DMF is only effective in solvating cations.)