17 Thiols

13.7 Thiols | Organic Chemistry

Introduction

The lesson focuses on thiols, their naming, synthesis, and reactions. Although thiols and sulfides are relatively minor functional groups, they have some biological relevance.

Main Points

• Naming Thiols:

- Thiols are the sulfur equivalent of alcohols. They are named similarly to alcohols but use 'thiol' as the suffix (e.g., propane-1-thiol).

- When thiols are not the highest priority function in a molecule, they are named as 'mercapto' substituents (e.g., 3-mercapto propane-1-ol).

• Synthesis of Thiols:

- The primary method of synthesizing thiols is via an SN2 reaction, typically with sodium hydrosulfide as the nucleophile.

- The process involves backside attack and displacement of a leaving group by an SH group, forming a thiol.

• Reaction of Thiols:

- Thiols can undergo oxidation to form disulfides, a process that is reversible with reducing agents.

- This reaction has biological significance, particularly in the formation of disulfide bridges in proteins, such as those in hair. These bridges are key to the structure and function of proteins.

• Biological Relevance:

- Cysteine, an amino acid, can form disulfide bridges under oxidative conditions, impacting the structure of proteins.

- The concept of disulfide bridges is notably applied in hair treatments like perms, where reducing agents break these bonds to reshape the hair, and oxidizing agents reform them to lock the new shape.

Conclusion

Thiols, while not extensively covered in many curriculums, play a significant role in biochemistry, especially in protein structure through disulfide bridges. Understanding their synthesis and reactions offers insight into their biological and chemical importance.