13.7 Thiols | Organic Chemistry
TLDRThe lesson focuses on the synthesis and reactions of thiols, a minor functional group similar to alcohols but with a sulfur (SH) group instead of a hydroxyl (OH) group. Thiols are named with the suffix 'thiol' and can be referred to as 'mercapto' when a substituent. The primary method for synthesizing thiols is through an SN2 reaction using a strong nucleophile like sodium or hydrogen sulfide. Thiols are significant in biology, as they can form disulfide bridges, which are crucial for the structure and stability of proteins. An example of this is the disulfide bonds in hair, which are broken and reformed during the process of getting a perm. The lesson also mentions the reversibility of disulfide bond formation, which is essential in both single and multiple peptide structures.
Takeaways
- 📚 The lesson focuses on the naming and synthesis of thiols and their reactions, which are relatively minor functional groups.
- 🧪 Thiols are the sulfur equivalent of alcohols, with the 'SH' group replacing the 'OH' group, and are named similarly with the suffix '-thiol'.
- 🔡 When thiols are not the highest priority functional group in a molecule, they are named as a 'mercapto' substituent.
- 🧬 The synthesis of thiols is typically achieved via an SN2 reaction with a strong nucleophile, such as sodium or hydrogen sulfide.
- 🔁 Thiols can undergo oxidation to form disulfide bonds, which is a reversible process that can be reversed with a reducing agent.
- 🌟 Disulfide bonds are biologically significant, playing a crucial role in the structure of peptides and proteins.
- 💇 Disulfide bridges are also found in hair, and were utilized in the process of obtaining a 'permanent' or 'perm' in hair styling.
- 🧪 The formation of a disulfide bridge involves two cysteine residues coming close together and undergoing oxidation.
- 📈 The process of a perm involves initially breaking disulfide bonds in hair with a reducing agent and then reforming them with an oxidizing agent to lock in a new hairstyle.
- 📚 The lesson is not part of many textbooks or curriculums, so it may be skipped by those who do not encounter thiols and sulfides in their studies.
- 📝 For those studying thiols, understanding their naming, synthesis, and the formation of disulfide bonds is essential for grasping their biological relevance.
- 🔗 Additional study materials, including practice problems and final exam reviews, can be found on chatsprep.com for those seeking further resources.
Q & A
What is the primary focus of this lesson?
-The primary focus of this lesson is the naming, synthesis, and reactions of thiols, which are sulfur-containing functional groups similar to alcohols but with an SH group instead of an OH group.
How are thiols named in comparison to alcohols?
-Thiols are named similarly to alcohols, but instead of using the suffix 'ol' for alcohols, the suffix 'thiol' is used for thiols. If the thiol is not the highest priority functional group, it is named as a 'mercapto' substituent.
What is a common nucleophile used to form thiols in an SN2 reaction?
-A common nucleophile used to form thiols in an SN2 reaction is sodium sulfide (NaSH), due to sulfur's strong nucleophilic properties.
What is the major reaction associated with thiols?
-The major reaction associated with thiols is the formation of a disulfide, which occurs when two thiols are oxidized and dimerize to form a disulfide bond.
Why are disulfide bridges biologically significant?
-Disulfide bridges are biologically significant because they contribute to the structure and stability of proteins. They can form within a single peptide or connect two separate peptides, providing structural integrity.
How do disulfide bonds relate to the process of getting a permanent or a perm in hair?
-Disulfide bonds are present in the protein structure of hair. During a perm, a reducing agent is applied to break these bonds, allowing the hair to be reshaped. An oxidizing agent is then used to reform the disulfide bonds, locking the hair into the new shape.
What is the term used to describe the sulfur equivalent of an alcohol?
-The sulfur equivalent of an alcohol is called a thiol.
How does the naming of thiols change when they are not the highest priority functional group in a molecule?
-When thiols are not the highest priority functional group, they are named as a substituent using the term 'mercapto'.
What is the role of a leaving group in the SN2 reaction for thiol formation?
-The leaving group in the SN2 reaction for thiol formation is replaced by a strong nucleophile, such as an SH group, to form a thiol.
Why is sulfur considered one of the best nucleophiles?
-Sulfur is considered one of the best nucleophiles due to its ability to form strong nucleophilic species with a negative charge, and even when neutral, as in the case of H2S, it remains a reasonably strong nucleophile.
What is the term for the connection between two cysteine residues in a protein through a disulfide bond?
-The term for the connection between two cysteine residues in a protein through a disulfide bond is a disulfide bridge.
How can the disulfide bonds in hair be temporarily broken to allow for a perm?
-The disulfide bonds in hair can be temporarily broken by applying a reducing agent, which allows the hair to be reshaped. After reshaping, an oxidizing agent is applied to reform the disulfide bonds and lock the hair into the new shape.
Outlines
🧪 Nomenclature and Synthesis of Thiols
The first paragraph introduces the topic of thiols, which are the sulfur analogs of alcohols. It explains that thiols are named similarly to alcohols, with the suffix 'thiol' instead of 'ol'. The paragraph also discusses the naming of thiols as substituents, using 'mercapto' as a prefix when the thiol group is not the highest priority functional group in the molecule. The synthesis of thiols is covered, highlighting the use of an SN2 reaction with a strong nucleophile like sodium or hydrogen sulfide (H2S) to replace a leaving group with a thiol group. This is the primary method for creating thiols, which are considered relatively minor functional groups.
🔁 Disulfide Formation and Biological Significance
The second paragraph delves into the major reaction of thiols, which is the formation of disulfides. This process involves the oxidation and dimerization of two thiol molecules to form a disulfide bond, a reaction that is reversible with the addition of a reducing agent. The biological relevance of disulfide bonds is emphasized, particularly in the structure of proteins where they form disulfide bridges. The example of cysteine residues in proteins undergoing oxidation to form these bridges is provided. The paragraph also mentions the historical use of disulfide bonds in the hair perm process, where reducing agents break the bonds to allow reshaping of the hair, and oxidizing agents are used to lock in a new style.
Mindmap
Keywords
💡Thiol
💡Mercapto
💡Sulfides
💡SN2 Reaction
💡Nucleophile
💡Disulfide
💡Disulfide Bridge
💡Cysteine Residue
💡Biological Relevance
💡Perm
💡Leaving Group
Highlights
The lesson covers the synthesis and reactions of thiols, which are a relatively minor functional group.
Thiols are the sulfur equivalent of alcohols, with an SH group instead of an OH group.
Thiols are named similarly to alcohols, with the suffix 'thiol' instead of 'ol'.
When thiols are not the highest priority functional group, they are named as a 'mercapto' substituent.
The term 'mercapto' is an old common way of referring to sulfur.
Synthesis of thiols can be achieved through an SN2 reaction using a strong nucleophile like sodium.
Sulfur is one of the best nucleophiles, even when neutral as in H2S.
The major reaction for thiols is the formation of disulfides through oxidation.
Disulfide formation is reversible and can be reduced to break the disulfide bond.
Disulfide bridges have biological relevance, playing a key role in the structure of peptides and proteins.
Cysteine residues in proteins can form disulfide bridges, which are important for protein structure.
Hair contains disulfide bridges, which were manipulated in the process of getting a 'perm'.
Perms involved breaking disulfide bonds with a reducing agent and reforming them to lock in a new hair shape.
Disulfide bridges can be part of a single peptide structure or connect two separate peptides.
The lesson briefly covers thiols and their biological relevance, making it a compact yet informative session.
For further study materials, including practice problems and final exams, consider the premium course on Chatsprep.com.
Transcripts
Browse More Related Video
13.8 Sulfides | Organic Chemistry
12.6 Substitution Reactions of Alcohols | Organic Chemistry
13.2 Synthesis of Ethers | Organic Chemistry
19.4a Formation of Hemiacetals and Acetals Addition of Alcohols | Organic Chemistry
12.1 Naming Alcohols | Organic Chemistry
12.4 Grignard Reagents | Organic Chemistry
5.0 / 5 (0 votes)
Thanks for rating: