Exam 2 Topics

Chapter 4

Understand the chair-to-chair conformation ring flip in cyclohexane and its effect on substituents.

Understand the preference for equatorial substituents (consistent with cis and trans relationships).

Understand stereoisomerism in rings (cis-trans isomerism).

Be able to answer the questions: Which is the most stable conformer? Which is the most stable isomer?

Chapter 5

Be able to identify chiral and achiral molecules and to identify a plane of symmetry.

Identify stereogenic centers. Know that 2ⁿ = maximum number of stereoisomers.

Know the definitions of enantiomers, diastereomers, and meso compound.

Be able to label the relationship between any given structures.

Be able to draw all the stereoisomers for molecules with one and two stereogenic centers.

Be able to assign R or S configurations in a molecule. Be able to draw a molecule with R or S configurations.

Understand optical activity and specific rotation.

Know the difference in physical and chemical properties for enantiomers and diastereomers.

Chapter 6

Know the names of the three common types of intermediate.

Know how to use mechanism arrows.

Be able to calculate ΔH^o for a reaction, given bond energy values.

Know the relationship between ΔG^o and K, ΔH^o and ΔS^o .

Be able to predict the sign and rough magnitude of ΔS^o for a given reaction.

Be able to construct an energy diagram given a mechanism.

Given an energy diagram, know how to predict the sign of ΔG^o and whether K is > or < one.

Know how to identify transition states, relative rates and intermediates on an energy diagram.

Understand the meaning of the terms in a rate law expression and how concentration changes affect the rate.

Given a mechanism, be able to write the rate law.

Chapter 7

Identify primary, secondary and tertiary halides and carbocations. Know the relative stabilities of the latter.

Be able to identify the nucleophile, leaving group and reaction site in a nucleophilic substitution reaction.

Given a series of leaving groups, be able to rank them from best to worst.

Given a series of nucleophiles (and, perhaps, the solvent), be able to rank them from best to worst.

Given the structure of a solvent molecule, be able to identify it as polar protic or polar aprotic.

Understand the effect of solvent on nucleophilicity.

Be able to write the correct mechanism for any nucleophilic substitution reaction.

Be able to construct an energy diagram for either mechanism, S_N1 or S_N2.

Know the rate laws for S_N1 and S_N2 mechanisms.

Know the stereochemistry associated with S_N1 and S_N2.

Be able to write the products, with stereochemistry, for any substitution reaction.

Know the effect of R groups on each mechanism.

Know the reactivity of aryl and vinyl halides.

Given a substitution reaction product, be able to supply one or more of the reactants.

Understand the Hammond postulate.