Loading...

CHEM104: Organic Chemistry II

Unit 2: Thiols and Sulfides   Thiols and sulfides are the "sulfur equivalent" of alcohols and ethers.  You can replace the oxygen atom of an alcohol with a sulfur atom to make a thiol; similarly, you can replace the oxygen atom in an ether with S to make the corresponding alkyl sulfide.  This is because thiols contain the C-S-H functional group, while sulfides contain the C-S-C group. 

Thiols are often called “mercaptans,” a reference to the Latin term mercurium captans(capturing mercury), since the -SH group forms strong bonds with mercury and its ions.  It is useful to know this nomenclature, because one day you may be looking for a bottle of butanethiol but will find that it is labeled butyl mercaptan!  Thiols, like alcohols, can form hydrogen bonds with other polar, protic molecules.  However, thiols are usually more acidic and volatile than are alcohols.  The thiol functional group is incorporated in many biological molecules, such as the essential amino acid cysteine and the coenzyme A.

Sulfides are less common than thiols as naturally occurring compounds.  However, sulfides—especially disulfides (C-S-S-C)—have important biological functions, mainly in reducing agents (antioxidants).  Note that the rigid, three-dimensional structure of an antibody is determined by cross-linking disulfide bonds.        

Unit 2 Time Advisory
This unit will take you 3.25 hours to complete.

☐    Subunit 2.1: 1 hour

☐    Subunit 2.2: 2.25 hours

Unit2 Learning Outcomes
Upon successful completion of this unit, the student will be able to:
- Derive the name of thiols and sulfides from their molecular structures, and vice versa. - Plan the synthesis of a given thiol and sulfide indicating the necessary reagents and reaction conditions. - Plan the conversion of thiols into disulfides using the appropriate reagents and reaction conditions.

2.1 Nomenclature of Thiols and Sulfides   - Reading: University of Calgary: Professor Ian Hunt’s "Basic IUPAC Organic Nomenclature: Thiols" Link: University of Calgary: Professor Ian Hunt’s "Basic IUPAC Organic Nomenclature: Thiols" (HTML)

 Instructions:Please click on the link above, and study this webpage
to learn about the nomenclature of thiols.  Then, go through the
practice problems at the bottom of the webpage.  Note that thiols
are the sulfur analogies or alcohols, and as with alcohols, they are
named by identifying the longest chain with the –SH group as the
base name of the molecule.Please note that this resource requires
Java.  

 This reading and practice problems should take approximately 30
minutes to complete.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.     
  • Reading: University of Calgary: Professor Ian Hunt’s "Basic IUPAC Organic Nomenclature: Thioethers or Sulfides" Link: University of Calgary: Professor Ian Hunt’s "Basic IUPAC Organic Nomenclature: Thioethers or Sulfides" (HTML)

    Instructions: Please click on the link above, and study this webpage to learn about the nomenclature of thioethers and sulfides.  Then, go through the practice problems at the bottom of the webpage. Note that thioethers, also named as sulfides, contain the group R-S-R and are named similarly to alcohols. This unit will teach you when to name a molecule as a thioether and when to name as a sulfide.Please note that this resource requires Java.

    This reading and practice problems should take approximately 30 minutes to complete.

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

2.2 Synthesis and Reactivity of Thiols and Sulfides   - Reading: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Sulfur and Phosphorus Compounds” Link: Michigan State University: Professor William Reusch’s Virtual Textbook of Organic Chemistry: “Sulfur and Phosphorus Compounds” (HTML)

 Instruction: Read the sections on “Nucleophilicity of Sulfur
Compounds” and “Oxidation States of Sulfur Compounds.” Note that
thiols and sulfides behave differently from their alcohol and ether
counterparts. Thiols are much stronger acids than alcohols. Also,
important is sulfur’s six oxidation states in compounds compared to
oxygen’s two. Read the sections of this article to understand the
reasons why.   

 Reading these sections and taking notes should take approximately 1
hour and 30 minutes to complete.  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-NoDerivs 3.0
License](http://creativecommons.org/licenses/by-nc-nd/3.0/). It is
attributed to Professor William Reusch, and the original version can
be found
[here](http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/special2.htm).
  • Web Media: YouTube: EducatorVids’ "Organic Chemistry: Thiols and Thioethers” Link: YouTube: EducatorVids’ "Organic Chemistry: Thiols and Thioethers" (YouTube)
     
    Instructions: Please click on the link above, and watch this brief video (2:36 minutes).  Learn about the reaction of NaS with a dihalide to form a sulfide ring.

    Viewing this lecture several times and taking notes should take less than 15 minutes to complete.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Reading: University of California, Davis: UC Davis ChemWiki: "Redox Reactions Involving Thiols and Sulfides" Link: University of California, Davis: UC Davis ChemWiki: "Redox Reactions Involving Thiols and Sulfides" (HTML)
     
    Instructions: Read the section titled “Disulfide Bridges in Proteins." Note that these reactions cover the important reactivity of sulfur compounds in biological systems, in particular the oxidation of thiols to form a disulfidebridge in proteins.

    Reading this section and taking notes should take approximately 30 minutes to complete.
      
    Terms of Use: This resource is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License. It is attributed to the University of Davis, California, ChemWiki, and the original version can be found here.