Chem 241 Review for Exam 3 / Final 12/08
McMurry 7th Ed
Objectives: You should be able to:
1. Perform objectives for Exams 1 and 2 given on previous sheets.
Chapter 8: Alkynes: Intro to Organic Synthesis
Topics Covered:
Naming alkynes; Enyne; vicinal;
Electrophilic addition and elimination reactions; tautomers,
Lindlar catalyst, Acetylide anions
Synthesis reactions
You should be able to:
1. Name acyclic and cyclic alkynes, and draw structures corresponding to names.
2. Predict the relative stability of alkyne bonds.
3. Show reactions of preparation of alkynes:
Dehydrohalogenation of vicinal dihalides
o (2KOH, ethanol) or
o (2NaNH2, NH3)
Alkylation of acetylide anions
o NaNH2, 2. RCH2X)
4. Predict the products of electrophilic or radical additions to alkenes: (remember
regiochemistry and stereochemistry)
Addition of hydrogen halides
o (1 or 2 eq HX, ether) (Markovnikov regiochemistry) or
o (1 or 2 eq HX, H2O2) (non-Markovnikov)
Addition of water and alcohols
o (H+, H2O or R-OH) including carbocation rearrangements. (Markovnikov)
Addition of halogens in
o nonpolar solvent (1 or 2 eq X2, CH2Cl2) (anti stereochemistry) or
o polar solvent (1 or 2 eq X2, H2O) or (1 or 2 eq X2, R-OH) (Markovnikov + anti)
Oxymercuration
o (Hg2SO4, H2SO4, H2O)
Hydroboration-Oxidation
o (1. BHR2 2. H2O2, NaOH, H2O)
Reduction:
o Hydrogenation (2H2, Pd/C or Pt/C, or Ni) (to alkane)
o Hydrogenation (H2, Lindlar’s cat) (to cis alkene)
o (Li or Na, NH3) (to trans alkene)
5. Correctly show the mechanism of addition reactions to alkynes.
6. Perform tautomerization of enols and carbonyls and apply it to alkyne chemistry.
7. Predict and compare the stability of saturated and unsaturated carbocation intermediates.
8. Predict the relative acidities of hydrocarbons and the strength of their corresponding
bases.
9. Perform substitution reactions on alkynes using acetylide anion intermediates.
10. Synthesize a target molecule from a given starting material using reactions known to you.
11. Summarize the industrial uses of acetylene.
