Loading...

CHEM103: Organic Chemistry I

Unit 4: Alkyl Halides   The alkyl halide is the first class of reactive molecules you will encounter in your organic chemistry course (as you may recall, alkanes are generally considered low reactive molecules).  Alkyl halides are halogen-substituted alkanes, which are also known as haloalkanes or halogenoalkanes.  The characteristic functional group is the carbon-halogen bond (recall that fluorine, chlorine, bromine, and iodine are the four halogens).  The most widely used alkyl halides are probably the CFCs (chlorofluorocarbons), which are used as refrigerants in home refrigerators and car air conditioning systems.  Alkyl halides are also found in flame-retardants and fire extinguishers and used as solvents (dichloromethane, chloroform, etc.) and reagents in organic synthesis.  After learning the nomenclature, structural, and physical properties of alkyl halides, you will discover two classes of chemical reactions: the nucleophilic substitution (SN) and the nucleophilic elimination (E).  These classes are typical of the carbon-halogen bond and they occur following two distinct reaction mechanisms: unimolecular (SN1 or E1) or bimolecular (SN2 and E2).  In this unit, you will learn how to predict the mechanism (and therefore the reaction products) by evaluating the nature and structure of the alkyl halides, the strength of the nucleophile, and reaction conditions.  This unit also introduces the concepts of chirality, stereocenters, and optical activity.  Understanding how to synthesize molecules with the desired chiral centers is critical to the pharmaceutical industry.

Unit 4 Time Advisory
This unit will take approximately 29.25 hours to complete.

☐    Subunit 4.1: 9 hours

☐    Sub-subunit 4.1.1: 0.75 hour

☐    Sub-subunit 4.1.2: 0.25 hour

☐    Sub-subunit 4.1.3: 5.5 hours

☐    Sub-sub-subunit 4.1.3.1: 2.5 hours       

☐    Sub-sub-subunit 4.1.3.2: 2 hours

☐    Sub-sub-subunit 4.1.3.3: 1 hour         

☐    Sub-subunit 4.1.4: 2.5 hours

☐    Subunit 4.2: 20.25 hours

☐    Sub-subunit 4.2.1: 3 hours

☐    Sub-subunit 4.2.2: 2.5 hours

☐    Sub-subunit 4.2.3: 5.5 hours

☐    Sub-subunit 4.2.4: 4.25 hours

☐    Sub-subunit 4.2.5: 3.5 hours

☐    Sub-subunit 4.2.6: 1.5 hours

Unit4 Learning Outcomes
Upon successful completion of this unit, the student will be able to:

  • Derive the name of alkyl halides from their molecular structure and vice versa. 
  • Define key concepts such as chirality, optical activity, enantiomorphism, and diastereoisomers.
  • Draw chiral isomers using Fischer projections.
  • Define carbocations and estimate their relative stability based on their molecular structure. 
  • Describe the mechanisms of nucleophilic substitution reactions for SN1 andSN2 reactions.
  • Describe the mechanisms of elimination reactions for E1 andE2 reactions.
  • Explain which factors and reaction conditions favor substitution or elimination reactions.
  • Describe reactions of alkyl halides with reducing metals, such as the formation of Grignard reagents.

4.1 Nomenclature, Structural and Physical Properties   4.1.1 Nomenclature of Alkyl Halides   - Web Media: Khan Academy: Organic Chemistry: "Naming Alkyl Halides" Link: Khan Academy: Salman Khan’s “Naming Alkyl Halides” (HTML)
 
Instructions: Please watch the video, which explains how alkyl halides are named using the IUPAC system (9:03 minutes).

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-NoDerivs 3.0 Unported
License](http://creativecommons.org/licenses/by-nc-nd/3.0/). It is
attributed to the Khan Academy.

4.1.2 Occurrence of Halides   - Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Occurrence of Alkyl Halides" Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Occurrence of Alkyl Halides" (HTML)
 
Instructions: Read this unit to know the natural occurrence of alkyl halides.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above. 

4.1.3 Stereoisomers   4.1.3.1 Chiral Centers   - Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Stereoisomer Part II" Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Stereoisomers Part II” (HTML)
 
Instructions: Read the sections titled “Chirality & Symmetry,” “Enantiomorphism,” and “Optical Activity.”  This resource also covers the topics outlined in subunits 4.1.3.1.1 through 4.1.3.1.3.

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.  

4.1.3.1.1 Chirality and Symmetry Elements   4.1.3.1.2 Enantiomorphism   4.1.3.1.3 Optical Activity   4.1.3.2 Chiral Configurations   - Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Chiral Configurations" Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: Chiral Configurations” (HTML)
 
Instructions: Read the entire chapter on this webpage.  Focus on these specific topics: “Designating the Configuration for Chiral Centers,” “Compounds with Two or More Chiral Centers,” “Fischer Projection Formulas,” “Achiral Diastereomers (meso Compounds),” “Other Configurational Notations,” “Resolution of Racemates,” and “Conformational Enantiomorphism.”  This resource also covers the topics outlined in subunits 4.1.3.2.1 through 4.1.3.2.9.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.                

  • Web Media: Khan Academy: Salman Khan’s “Cahn-Ingold-Prelog System for Naming Enantiomers” and “R,S (Cahn-Ingold-Prelog) Naming Example 2” Link: Khan Academy: Salman Khan’s: “Cahn-Ingold-Prelog System for Naming Enantiomers” (HTML) and “R,S (Cahn-Ingold-Prelog) Naming Example 2” (HTML)
     
    Instructions: Please watch these two videos, which explain the nomenclature of enantiomers (22:10 minutes).  

    Terms of Use: This resource is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. It is attributed to the Khan Academy.

  • Web Media: YouTube: Your Formula Sheet: “Fischer Projection” Link: YouTube: Your Formula Sheet: “Fischer Projection” (YouTube)
     
    Instructions: Please watch the entire video (2:42 minutes).  This resource covers subunits 4.1.3.2.1 through 4.1.3.2.9.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

  • Assessment: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Stereoisomers: Practice Problems” Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Stereoisomers: Practice Problems” (HTML)
     
    Instructions: Select a problem from the Practice Problems scroll-down menu.  Practice on all problems.  This resource covers the topics in subunits 4.1.3.2.1 through 4.1.3.2.9.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

4.1.3.2.1 Chiral Configurations   4.1.3.2.2 Configurational Nomenclature   4.1.3.2.3 Compounds with Several Stereogenic Centers   4.1.3.2.4 Stereogenic Nitrogen   4.1.3.2.5 Fischer Projection Formulas   4.1.3.2.6 Achiral Diastereomers   4.1.3.2.7 Other Configurational Notations   4.1.3.2.8 Resolution   4.1.3.2.9 Conformational Enantiomorphism   4.1.4 Summary of Isomerism   - Web Media: Khan Academy: Salman Khan’s “Stereoisomers, Enantiomers, Diastereomers, Constitutional Isomers and Meso Compunds” Link: Khan Academy: Salman Khan’s: “Stereoisomers, Enantiomers, Diastereomers, Constitutional Isomers and Meso Compunds” (HTML)
 
Instructions: Please watch the videos, which discuss different isomer configurations (13:36 minutes).  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-NoDerivs 3.0 Unported
License](http://creativecommons.org/licenses/by-nc-nd/3.0/). It is
attributed to the Khan Academy.
  • Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Isomer Summary" Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Isomer Summary"(HTML)

    Instructions: Please read the entire webpage for a review of the different types of isomerism.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

4.2 Reactivity of Alkyl Halides: Substitution and Elimination of the "Halide"   4.2.1 Carbocations (Positively Charged Carbons)   - Reading: Chemguide: Jim Clark’s “Carbocations” Link: Chemguide: Jim Clark’s “Carbocations” (HTML)
 
Instructions: Read the entire webpage.  This resource covers subunits 4.2.1.1 through 4.2.1.2.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

4.2.1.1 Relative Strengths of Carbocations   4.2.1.2 Carbocation Rearrangements   4.2.2 Affecting Substitution and Elimination Reactions   - Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Alkyl Halide Reactions" Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Alkyl Halide Reactions" (HTML)
 
Instructions: Read the entire section titled "Alkyl Halide Reactions."
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

4.2.3 Nucleophilic Substitutions: SN2 and SN1 Mechanisms   - Reading: Chemguide: Jim Clark’s “Nucleophilic Substitution” Link: Chemguide: Jim Clark’s “Nucleophilic Substitution” (HTML)
 
Instructions: Read the entire webpage.  This resource also covers the topics outlined in subunits 4.2.3.1 through 4.2.3.8.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

4.2.3.1 Rate Law of SN2 (Bimolecular)   4.2.3.2 Mechanism of SN2 (One-Step, Concerted Mechanism)   4.2.3.3 Stereochemistry of SN2 (Inversion of Stereochemistry)   4.2.3.4 Conditions Favoring SN2 (Less Substituted carbons, Non-polar Aprotic Solvent)   4.2.3.5 Rate Law of SN1 (Unimolecular; Rate-Dependent on Only Substrate)   4.2.3.6 Mechanism of SN1 (Two-Step Mechanism)   4.2.3.7 Stereochemistry of SN1 (Racemic)   4.2.3.8 Conditions Favoring SN1 (More Substituted Carbons, Allylic and Benzylic Carbons, Polar Protic Solvent)   4.2.4 Elimination Reactions: E2 and E1 Mechanisms   - Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Elimination Reactions of Alkyl Halides"

Link: Michigan State University: Professor William Reusch’s
[*Virtual Textbook of Organic* *Chemistry:* “Elimination Reactions
of Alkyl
Halides"](http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/alhalrx3.htm#hal6)
(HTML)  
  

Instructions: Read the entire webpage to learn about elimination
reactions.  This resource covers subunits 4.2.4.1 through 4.2.4.6.  
    
 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.  
  • Reading: Chemguide: Jim Clark’s “Elimination from Unsymmetric Halogenoalkanes” Link: Chemguide: Jim Clark’s “Elimination from Unsymmetric Halogenoalkanes” (HTML)
     
    Instructions: Read the entire webpage.  This resource covers subunits 4.2.4.1 through 4.2.4.6.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

  • Web Media: Khan Academy’s "E1 Reactions" and "E2 Reactions" Link: Khan Academy’s "E1 Reactions" (HTML) and "E2 Reactions" (HTML)
     
    Instructions: Watch both videos in their entirety; each video lecture is about 9 minutes.  This resource covers subunits 4.2.4.1 through 4.2.4.6.

    Terms of Use: These resources are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. They are attributed to the Khan Academy.

  • Web Media: Khan Academy: Salman Khan’s “E2 Reactions”; “E1 Reactions”; and “Zaitsev’s Rule” Link: Khan Academy: Salman Khan’s: “E2 Reactions” (HTML); “E1 Reactions” (HTML); and “Zaitsev’s Rule” (HTML)
     
    Instructions: Please watch these three videos, which describe E1 and E2 reaction mechanisms and how to predict the products based on Zaitsev’s rule (31:44 minutes).  

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

4.2.4.1 Rate Law of E2 (Bimolecular)   4.2.4.2 Mechanism of E2 (One-Step, Concerted Mechanism)   4.2.4.3 Conditions favoring E2 (Strong Base)   4.2.4.4 No Geometrical Preference (E1)   4.2.4.5 Mechanism of E1 (Two-Step Mechanism)   4.2.4.6 Conditions Favoring E1 (Weak Base)   4.2.5 Summary of Substitution vs. Elimination   - Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Summary of Substitution vs. Elimination" Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Summary of Substitution vs. Elimination" (HTML)
 
Instructions: Use this table as a guide to determine under which conditions a particular reagent may undergo nucleophilic substitution or elimination.  Note, however, that there might be exceptions to these rules of thumb.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

  • Web Media: Khan Academy: Salman Khan’s “Comparing E2 E1 Sn2 Sn1 Reactions”; “E2 E1 Sn2 Sn1 Reactions Example 2”; and “E2 E1 Sn2 Sn1 Reactions Example 3” Link: Khan Academy: Salman Khan’s: “Comparing E2 E1 Sn2 Sn1 Reactions” (HTML); “E2 E1 Sn2 Sn1 Reactions Example 2” (HTML); and “E2 E1 Sn2 Sn1 Reactions Example 3” (HTML)
     
    Instructions: Please watch these three videos, which provide demonstrations of nucleophilic substitution and elimination reaction mechanisms (28:50 minutes).  

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

4.2.6 Reactions of Alkyl Halides with Reducing Metals: Grignard and Alkyl Lithium Reagents   - Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Alkyl Halide Reactivity" Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Alkyl Halide Reactivity" (HTML)
 
Instructions: Read the entire webpage, “Organometallic Compounds” through “Reactions of Dihalides.”  This resource covers the topics outlined in subunits 4.2.6.1 through 4.2.6.3. 
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

  • Web Media: YouTube: ChemProfessor98's Channel: "Orgo Chem-Grignard Reaction" Link: YouTube: ChemProfessor98's Channel: "Orgo Chem-Grignard Reaction" (YouTube)
     
    Instructions: Watch this tutorial video about the Grignard Reaction (7:46 minutes).  This resource covers subunits 4.2.6.1 through 4.2.6.3.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.  

  • Assessment: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Alkyl Halide Reactivity: Practice Problems" Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Alkyl Halide Reactivity: Practice Problems" (HTML)

    Instructions: Use the Practice Problems scroll-down menu to select, and complete all the problems.  This resource covers topics outlined in subunits 4.2.6.1 through 4.2.6.3.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpages above.  

4.2.6.1 Grignard reagents   4.2.6.2 Alkyl lithium   4.2.6.3 Elimination Reactions of Dihalides