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Ian R Gould  > igould@asu.edu CHM 234 : General Organic Chemistry II  > Spring 2012
 CHM 234/238
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First Semester Problems | Second Semester Problems | Spectroscopy Problems | Retrosynthesis Problems | Mechanism Problems
  worked problems in QUICKTIME format   :     worked problems in FLASHPLAYER format   :     problems with hints
First Semester Problems  
Bonding & Structure I : The Basics
Electron Energies
Organic Structures
Stereoisomers
Structures/Isomers
 Degrees of Unsaturation
Lewis Structures/Isomers
Formal Charges
Functional Groups
Cumulative Problems
Bonding & Structure II : Better Models
Atomic Orbitals
Hybridization
Molecular Orbitals 
Hybridization and Angles : VSEPR
 Electron Energies/Molecules
Dipole Moments
Homolytic Bond Disociation
Cumulative Problems
Resonance : Delocalized Electrons
Orbitals and Delocalization
Resonance Contributors 
 Minor Resonance Contributors 
Cumulative Problems
Alkanes : 3D Structures
Alkane Nomenclature
Alkane Conformations 
 Cycloalkane Conformations  
Cumulative Problems
Acids and Bases : First Reactions
Acids and Bases
Relative Acidities
 Bronsted Acid/Base Reactions
Organic Reactions : How and Why
Classification
Recognizing Lewis Acids/Bases
Lewis Acid/Base Reactions 
 Curved Arrow "Pushing"
Revisit Electron Energies
 Mechanisms/Energy Diagrams 
Cumulative Problems 
Alkenes I : Electrophilic Addition
Alkene Nomenclature
Alkene Stabilities
 Alkene Reagents
Alkene Reactions
Cumulative Problems
Chirality : Left- and Right-Handed Molecules
Identifying Chirality
Fischer Projections (for MCAT only)
 Stereochemistry of Alkene Addition Reactions
Cumulative Problems
Alkyl Halides : Substitution and Elimination
SN2 Reactions
Distinguishing SN1 and SN2
E2 Eliminations 
 Distinguishing SN1, SN2, E1, E2
Cumulative Problems
Alkenes II : Introduction to Synthesis
Reaction Practice
 Cumulative Problems

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Second Semester Problems  
Retrosynthesis : Putting Reactions Together
1st Semester Synthesis Reactions
Identifying Synthons
 SN2 Reactions in Reverse
Retrosyntheis Practice
Alkynes : Developing Synthetic Methods
Alkyne Nomenclature
Alkyne Reactions
 Acetylide Reactions
Cumulative Problems
Alcohols : Oxidation and Reduction
Alcohol Nomenclature
Alcohol Acidity
Alcohol Reagents
 Alcohol Reactions
Reactions That Make Alcohols
Organometals : Carbon-Carbon Bonds
Practice Making C-C Bonds Backwards 
  
Ethers/Epoxides : Acid and Base Catalyzed Reactions
Ether/Epoxide Nomenclature Ether/Epoxide reactions
Conjugated Systems and Aromaticity: Revisit Molecular Orbital Theory
Diels-Alder Reactions
Molecular Orbitals of Conjugated Systems
F.M.O.'s and Cycloaddition Reactions
 F.M.O.'s and Electrocyclic Reactions
Pericyclic Reactions and Aromatic Transition States 
Aromaticity Practice
Benzenes : Electrophilic Aromatic Substitution
Benzene Nomenclature
Simple Benzene Reactions
 Simple Benzene Synthesis
Benzene Retrosynthesis
Aldehydes and Ketones : Nucleophilic Addition
Aldehyde/Ketone Nomenclature
Reactions That Make Aldehydes/Ketones
Reactions of Aldehydes/Ketones
 Wittig Related Reactions
Wittig Syntheses
Enols and Enolates : Acidities of Carbonyls
Aldol and Claisen Practice 
Aldol and Claisen in Reverse
 Malonic Acid Ethylacetoacetate Syntheses
Carboxylic Acids and Derivatives : Nucleophilic Substitution
Acid Nomenclature
 Derivative Nomenclature
Amines : Organic Bases
Nomenclature
Amine Synthesis
 Elimination Reactions

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Teach Yourself Spectroscopy Problems  
In these courses you will be asked to identify unknown structures using spectroscopy. You are not expected to memorize frequencies, on all tests you are provided with a correlation chart that contains all of the information you will need to interpret Infrared and NMR spectra, CLICK HERE. You should get used to using this chart since it is the that you will have on the tests. For NMR, however, it is often not necessary to use these charts, since you should have this CRUDE CHART "in your head". On the other hand, for infrared you should probably know MORE than is on this chart. You should be able to recognize the shapes of the different absorption bands without having to check their frequencies on the chart.
Abbreviated Suggested Procedure

Look at the spectra in this order: Mass, IR, 13C, then proton NMR.
1. Get molecular weight and elemental information from the mass spectrum
2. Get functional group information from the IR
3. Get the number of chemically inequivalent carbons, and confirm functionalities from 13C NMR
4. Compare the number of signals in proton and 13C NMR spectra to determine whether there are carbons without hydrogens. Note that one often sees a fairly close correlation between the chemical shifts of carbons and their corresponding hydrogens.
Click Here for a More Detailed Procedure

Learning Spectroscopy (notes..)
Information from Mass Spectra
Understanding Infrared Spectra
Interpreting Infrared Spectra
 Understanding NMR Spectra
NMR Problems 
Combined Spectral Problems starting with Mass Spectrum
Standard Problem 1
Standard Problem 2
Standard Problem 3
Challenging Problem 4
Challenging Combined Problem  		Standard Problem 5
Standard Problem 6
Standard Problem 7
Standard Problem 8
Challenging Problem 9
Combined Spectral Problems starting with Molecular Formula
Worked Problem #1 (click HERE for the spectra)                                Worked Problem #2 (click HERE for the spectra)
Easier Problem 1
Standard Problem 4
Standard Problem 7
Standard Problem 10
Standard Problem 13
Standard Problem 16
Standard Problem 19
Standard Problem 22
 Easier Problem 2
Standard Problem 5
Standard Problem 8
Standard Problem 11
Standard Problem 14
Standard Problem 17
Standard Problem 20
Standard Problem 23
 Easier Problem 3
Standard Problem 6
Standard Problem9
Standard Problem 12
Standard Problem 15
Standard Problem 18
Standard Problem 21

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Teach Yourself Retrosynthesis Problems  
You are required to be able to do simple retrosynthesis. The idea is to see if you can put together individual chemistry facts you have learned to do something useful. Synthesis is an important part of organic chemistry. These problems develop valuable thinking skills that are broadly useful.
Retrosynthesis is hard because you need to know BOTH the reactions, and how to solve the problems themselves. You will improve both by practice. Given below is a suggested procedure to solve these kinds of problems
Suggested Procedure

1 Except in simple cases, start from the product and work backwards (RETROsynthesis)
2 Look for the "skeleton" of the starting material in the product. Determine which C-C bonds have to be made. Look for C-C bonds close to functional groups, there are very few ways to simply put a C-C bond in the middle of an alkane chain
3 Summarize the functional group interconversions (FGI's) you need to do
4 Decide whether you will do a functional group transformation or do a C-C bond forming reaction (if required) first. Focus your attention on the C-C bond-forming reactions first. If you can't do one, then try a FGI. Specifically, if there is no suitable functional group close to a C-C bond you want to then put one there to help with the C-C bond reaction
5 Now you have a new compound to work back from. Go back to step number 2. Your procedure may not be going in the right direction, be prepared to repeat some of the steps in a different way, including the first one!

Practice Problems

Your primary resource for practice problems is The ASU RETROSYNTHESIS Teaching Web Site

The second resource are those problems summarized in the Table below. They are given in terms of the most recent functional group involved. There will often be more than one way of doing most of these problems and the answers represent only one solution. In some cases the answers may not be the best solution, but they illustrate a principle or are the only way of solving the problem with the information to date. In addition, you could use other reactions not covered in our courses. The problems here represent a range of difficulty from easy to challenging.
Alkyl Halides/Alkenes
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
 Problem 4  Answer 4
Problem 5  Answer 5
Problem 6  Answer 6
 Problem 7  Answer 7
Problem 8  Answer 8
Problem 9  Answer 9
Alkynes
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
 Problem 4  Answer 4
Problem 5  Answer 5
  
Alcohols
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
Problem 4  Answer 4
 Problem 5  Answer 5
Problem 6  Answer 6
Problem 7  Answer 7
Problem 8  Answer 8
 Problem 9  Answer 9
Problem 10  Answer 10
Problem 11  Answer 11
Ethers/Epoxides
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
 Problem 4  Answer 4
  
Conjugated Systems
Problem 1  Answer 1
    
Aromatic Systems
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
Problem 4  Answer 4
 Problem 5  Answer 5
Problem 6  Answer 6
Problem 7  Answer 7
Problem 8  Answer 8
 Problem 9  Answer 9
Problem 10  Answer 10
Aldehydes & Ketones
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
    
Enols/Enolates
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
 Problem 4  Answer 4
Problem 5  Answer 5
Problem 6  Answer 6
 Problem 7  Answer 7
Problem 8  Answer 8
Carboxylic Acids and Derivatives
Solved Problem    See The Solution 
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
Problem 4  Answer 4
 Problem 5  Answer 5
Problem 6  Answer 6
Problem 7  Answer 7
Problem 8  Answer 8
 Problem 9  Answer 9
Problem 10  Answer 10
Problem 11  Answer 11
Amines
Solved Problem    See The Solution 
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
Problem 4  Answer 4
 Problem 5  Answer 5
Problem 6  Answer 6
Problem 7  Answer 7
Problem 8  Answer 8
 Problem 9  Answer 9
Problem 10  Answer 10

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Practice Problems That Use a Minimal Set of Reactions

Retrosynthesis is difficult because it requires that you know a lot of reactions, AND, that you understand the problem-solving strategy. If you don't know the reactions, you can't solve the problems. Here are a series of simple problems that use only a basic minimal set functional group interconversion reactions (FGI's) and C-C bond-forming reactions that everybody should know towards the end of any organic chemistry course. These problems thus give you practice in the problem-solving process without having to worry about obscure reactions.
CLICK HERE For the list of minimal FGI's included in these problems
CLICK HERE For the list of basic C-C bond-forming reactions included in these problems
Problem 1  Answer 1
Problem 2  Answer 2
Problem 3  Answer 3
Problem 4  Answer 4
Problem 5  Answer 5
Problem 6  Answer 6
 Problem 7  Answer 7
Problem 8  Answer 8
Problem 9  Answer 9
Problem 10  Answer 10
Problem 11  Answer 11
Problem 12  Answer 12
 Problem 13  Answer 13
Problem 14  Answer 14
Problem 15  Answer 15
Problem 16  Answer 16
Problem 17  Answer 17
Problem 18  Answer 18

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Teach Yourself Mechanism Problems  
I don't have a lot of systematic mechanism problems yet, but here are a few, they increase roughly in difficulty as you go through them, with reactions that either make ring structures or contract ring structures towards the end. The last two problems, #18 and #19 and challenging!
Practice Problems
Problem 2
Problem 4
Problem 9
Problem 3
Problem 5
Problem 6
Problem 10
Problem 8
Problem 7
Problem 11
Problem 12
Problem 13
Problem 14
Problem 1
Problem 16
Problem 18
Problem 19

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