Exam 3 Topics (entered 4/7/08)

Chapter 8

Understand the hybridization and geometry of alkenes.

Know when an alkene has cis and trans isomers.

Be able to rank alkenes in order of their relative stabilities.

Be able to write the elimination product(s) that results from the reaction of a halide and a base.

Be able to recognize the common bases and know which are non-nucleophilic bases.

Given an alkyl halide (or any leaving group), a nucleophile/base, and possibly a solvent, be able to decide among S_N1, S_N2, E1 and E2 reactions.

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

Know that the most stable alkene is formed in an E1 reaction.

Know that the alkene formed in an E2 reaction must be formed from an antiperiplanar conformation of the halide. If there is a choice, the most stable alkene is formed fastest.

Know how to prepare alkynes by a double elimination reaction of geminal (halogens on the same carbon) or vicinal (halogens on adjacent carbons) dihalides and two equivalents of strong base.

Chapter 9

Be able to identify these three functional groups (alcohols, ethers and epoxides) and know the basic procedure for naming each.

Review the principles for determining the relative boiling points and solubilites of organic compounds.

Be able to prepare alcohols and ethers from primary halides and hydroxides or alkoxides (and from alkenes in chapter 10).

Be able to prepare an alkoxide from an alcohol.

Be able to prepare an epoxide from a halohydrin.

Know that –OH and –OR are poor leaving groups and won’t react with nucleophiles unless they are first converted to good leaving groups.

Know the reagents for converting an alcohol to an alkene (H₂SO₄, POCl₃ and pyridine) and be able to write the products of these reactions.

Be able to write the mechanism of an elimination reaction of an alcohol with H₂SO₄ – either E1 for sec. and tert. alcohols or E2 for primary.

Know the reagents for converting an alcohol to a halide (HX, SOCl₂ and pyridine, PBr₃) and be able to write the products (with stereochemistry) of these reactions.

Be able to write the mechanism for the reaction of HX with an alcohol (S_N1 for sec. and tert. alcohols or S_N2 for primary).

Be able to write the product of an alcohol with tosyl chloride.

Be able to write the product of the reaction of a tosylate with a good nucleophile.

Be able to identify reactions in which rearrangement may occur (usually those in which a secondary carbocation is formed as an intermediate) and to write a mechanism (and accompanying energy diagram) for a rearrangement reaction.

Be able to write the rearranged products for such reactions.

Be able to write the products and mechanism for the reaction of an ether with HX.

Be able to identify whether an epoxide will undergo substitution by an S_N2 mechanism (good nucleophile and/or basic conditions) or S_N1 mechanism (poor nucleophile and/or acidic conditions. Be able to write a detailed mechanism for each.

Be able use the decision about mechanism to show which carbon of the epoxide is attacked and the stereochemistry of the product.

Be able to do synthesis problems involving alcohols, ether and epoxides – that is, given a product molecule, be able to supply starting materials and reagents.

Chapter 10

Know that the pi bond of an alkene is weaker than the single bond and that alkenes generally act as nucleophiles in reactions.

Know the basic rules for naming alkenes.

Know how to assign E or Z configuration to appropriate alkenes.

Be able to show how to prepare an alkene from an alcohol and H₂SO₄, from an alcohol and POCl₃/ pyridine, and from a halide and strong base.

Be able to write the product of addition of HBr or HCl to an alkene, including the regiochemistry (Markovnikov) and stereochemistry (syn and anti).

Be able to write a mechanism for the addition of HX to an alkene (and energy diagram) and understand the basis for Markovnikov’s rule.

Know when rearranged products may occur during addition of HX.

Be able to write the product of addition of HOH or ROH in acid to an alkene, including the regiochemistry (Markovnikov) and stereochemistry (syn and anti).

Be able to write a mechanism for the addition of HOH or ROH in acid to an alkene.

Be able to write the product of addition of X₂ to an alkene, including the stereochemistry (anti only).

Be able to write the halonium ion mechanism for the addition of X₂ to an alkene.

Given a dihalide (with stereochemistry) be able to write an alkene (E or Z) from which it would be formed by addition of X₂.

Be able to write the product (a halohydrin or related) of addition of X₂ in the presence of an excess amount of another nucleophile like water or alcohol, including the stereochemistry (anti) and regiochemistry (the nucleophile goes to the most hindered carbon because of a developing positive charge there).

Be able to write the product of the addition of borane (BH₃) to an alkene.

Be able to write the product alcohol from the oxidation of the borane addition product with H₂O₂ and OH^-.

Know that the mechanism for the hydroboration reaction is a one-step mechanism without an intermediate.

Know the stereochemistry (syn addition) and regiochemistry (sometimes called “anti-Markovnikov”) for the hydroboration reaction.

Know that the alcohol formed from the borane addition product has retention of configuration.

Be able to use the two hydration reactions (water/acid and hydroboration/oxidation) to form different alcohols from the same alkene. Given an alcohol be able to show the appropriate alkene and reagents for preparing it.

Know how to calculate how many degrees of unsaturation are associated with a given molecular formula.

Chapter 11

Know the basic rules for naming alkynes.

Know how to prepare an alkyne by double elimination from a dihalide and two equivalents of base.

Know how to prepare an alkyne from its corresponding alkene (by addition of X₂ followed by double elimination).

Be able to write the product of the addition of one equivalent of HX to an alkyne, including the stereochemistry (anti addition) and regiochemistry (follows Markovnikov’s rule). Be able to write the product of the addition of two equivalents of HX to an alkyne.

Be able to write the product of the addition of both one equivalent of X₂ (anti addition) and two equivalents of X₂ to an alkyne.

Know that an enol (OH attached to a double bond) is normally unstable and isomerizes (tautomerizes) quickly to the keto form.

Be able to write the product of the addition of H₂O (with H₂SO₄ and HgSO₄) of an alkyne, including the regiochemistry (Markovnikov).

Be able to write the mechanism for the acid-catalyzed tautomerization of an enol to a ketone or aldehyde.

Be able to write the product of the addition of borane followed by oxidation with H₂O₂ and HO^-, including the regiochemistry (anti-Markovnikov).

Given a ketone or aldehyde be able to identify the alkyne from which it could be formed by one of the hydration reactions.

Know that terminal alkynes are much more acidic (pK_a ~25) than are other hydrocarbons like alkenes (pK_a ~45) or alkanes (pK_a~50) and the reason for the increased acidity.

Know which reagents are used to form alkynyl anions from terminal alkynes and how these anions can be used as nucleophiles in S_N2 reactions.

Be able to do synthesis problems using retrosynthetic analysis with the reactions presented thus far in the course (acid-base, substitution, elimination, addition reactions).