Chem 251 Fall 2012
Learning Objectives
Chapter 8 (last semester)
1. Write an electron-pushing mechanism for an SN2 reaction between an alkyl halide and a nucleophile. 2. Describe the rate law and relative rate of reaction of alkyl halides of different degree for an SN2 substitution reaction.
3. Describe the mechanistic detail of the SN2 mechanism relating the geometrical structure of the transition state to the stereochemistry of the reactant and product at the atom where substitution occurs.
4. Describe the effect of leaving group stability on the rate of an SN2 reaction.
5. Describe the effect of strength of nucleophile on the rate of an SN2 reaction. 6. Describe how nucleophilicity is influenced by solvent. 7. Describe how nucleophilicity is influenced by the size of the nucleophile.
8. Write an electron-pushing mechanism for an SN1 reaction between an alkyl halide and a nucleophile.
9. Describe the rate law and relative rate of reaction of alkyl halides for an SN1 substitution reaction.
10. Describe the mechanistic detail of the SN1 mechanism relating the geometrical structure of the transition state to the stereochemistry of the reactant and product at the atom where substitution occurs.
11. Describe the effect of leaving group stability on the rate of an SN1 reaction.
12. Describe the effect of strength of nucleophile on the rate of an SN1 reaction. 13. Determine whether a carbocation will undergo rearrangement via a 1,2-hydride or alkyl shift and draw the resulting cation. 14. Explain, with mechanistic specifics and discussion of the solvent, how partial racemization (with more inversion) can occur in an SN1 reaction. 15. Account for the non-reactivity of vinyl and aryl halides in nucleophilic substitution reactions. 16. Analyze information about alkyl halide, nucleophile, solvent, concentration, and temperature to predict whether a substitution will occur by an SN1 or SN2 mechanism. 17. Describe how the rate of a nucleophilic substitution reaction will be affected by an aprotic or a protic polar solvent. Chem 251 Fall 2012
Chapter 9 (last semester) 1. Write an electron-pushing mechanism for an E2 reaction between an alkyl halide and a base. 2. Describe the rate law and relative rate of reaction of alkyl halides of different degree for an E2 elimination reaction. 3. Describe the mechanistic detail of the E2 mechanism relating the geometrical structure of the transition state to the stereochemistry of the reactant and product at the atoms where elimination occurs. 4. Describe the effect of leaving group stability on the rate of an E2 reaction. 5. Describe the effect of the size of the base on distribution of products of an E2 reaction. 6. Predict the major product of an E2 reaction of an alkyl halide and a base, taking into account the size of the base and the identity of the halide. 7. Write an electron-pushing mechanism for an E1 reaction between an alkyl halide and a base. 8. Describe the rate law and relative rate of reaction of alkyl halides of different degree for an E1 elimination reaction. 9. Describe the mechanistic detail of the E1 mechanism relating the geometrical structure of the transition state to the stereochemistry of the reactant and product at the atoms where elimination occurs. 10. Predict the major product of an E1 reaction of an alkyl halide and a base, taking into account the possibility of a 1,2-hydride or alkyl shift. 11. Analyze information about alkyl halide, base, solvent, concentration, and temperature to predict whether a substitution will occur by an E1 or E2 mechanism. 12. Describe the stereoselective nature of the E2 reaction. 13. Describe the stereoselective nature of the E1 reaction. 14. Analyze substituted cyclohexanes to determine the reactivity and products in an E2 reaction. 15. Analyze information about alkyl halide, nucleophile/base, solvent, concentration, and temperature to predict whether the major product from reaction of the alkyl halide will arise by substitution or by elimination, and determine the likely mechanism. Chem 251 Fall 2012
Chapter 10 (selections; see more of chapter 10 below) 1. Write a chemical equation for the formation of an alkyl halide from an alcohol and a hydrohalic acid.
2. Write an electron-pushing mechanism for the SN2 reaction of an alcohol.
3. Write an electron-pushing mechanism for the SN1 reaction of an alcohol.
4. Determine from the degree of an alcohol whether it will react by an SN1 or SN2 mechanism. 5. Describe the effect of the halide on the rate of a reaction of a hydrohalic acid with an alcohol. 6. Describe the effect of the degree of the alcohol on the rate of a reaction of a hydrohalic acid with an alcohol.
7. Write a chemical equation for the reaction of an alcohol with PX3 (with pyridine). (X = Cl, Br, or I)
8. Write a chemical equation for the reaction of an alcohol with SOCl2 (with pyridine).
9. Write an electron-pushing mechanism for the reaction of an alcohol with PX3 (with pyridine). (X = Cl, Br, or I)
10. Write an electron-pushing mechanism for the reaction of an alcohol with SOCl2 (with pyridine). 11. Write a chemical equation for the formation of a sulfonate ester from an alcohol and a sulfonyl chloride (with pyridine). 12. Write an electron pushing mechanism for the formation of a sulfonate ester from an alcohol and a sulfonyl chloride (with pyridine). 13. Identify and distinguish between alkyl sulfonates (such as tosylates, mesylates, and triflates) and the analogous sulfonyl chlorides. 14. Know and understand the preparation of tosylates ,reactions of tosylates, and chemicals similar to tosylates such as the methanesulfonates (mesylates). 15. Describe the relationship of the stereochemistry of the reactant and product in a reaction to form an alkyl sulfonate from an alcohol. 16. Describe the relationship of the stereochemistry of the reactant and product in a nucleophilic substitution reaction of an alkyl sulfonate. 17. Write a chemical equation for the dehydration reaction of an alcohol with sulfuric acid (H2SO4), phosphoric acid (H3PO4), or a similar acid with a non-nucleophilic conjugate base (with pyridine) to form an alkene. 18. Write an electron-pushing mechanism for the dehydration reaction of an alcohol with sulfuric acid (H2SO4), phosphoric acid (H3PO4), or a similar acid with a non-nucleophilic Chem 251 Fall 2012
conjugate base (with pyridine) to form an alkene, taking into account the potential for a carbocation rearrangement.
19. Write a chemical equation for the reaction of an alcohol with P(O)Cl3 (with pyridine).
20. Write an electron-pushing mechanism for the reaction of an alcohol with P(O)Cl3 (with pyridine). 21. Determine from the degree of an alcohol whether it will react by an E1 or E2 mechanism.