ORG CHEM | Thiols

Thiols

also known as mercaptans, they are by the presence of a sulfhydryl group (-SH) attached to a carbon atom; similar to alcohols, but the oxygen atom in the hydroxyl group (-OH) is replaced by sulfur.

IUPAC Naming of Thiols

1. Identify the longest chain that contains the sulfhydryl group.

2. Number the chain nearest to the sulfhydryl group.

3. Follow the same rules when identifying and numbering substituents.

4. Assemble the name by adding -thiol after the main name. You can the number of the sulfhydryl group either before the main name or before the thiol suffix (e.g. 2-butanethiol or butane-2-thiol)

Common Naming of Thiols

Alkyl Group Connected to SH + “mercaptan”

Naming Compounds Where the Thiol is Not the Highest Priority

The thiol is mentioned as a substituent while the other functional group is used as the suffix. For example, a compound with a hydroxyl and a sulfhydryl could be named "“6-mercaptononan-2-ol

Polarity of Thiols

are weakly polar due to the small electronegativity difference between sulfur and hydrogen, the S-H bond is less polar than the O-H bond

Boiling Point of Thiols

have lower boiling points than alcohols of comparable molecular weight due to weaker hydrogen bonding from the smaller electronegativity of sulfur

Odor of Thiols

they are known for their strong, often unpleasant odors (e.g., the smell of garlic or rotten eggs); ethyl mercaptan is added to natural gas to detect leaks.

Solubility of Thiols

they are less soluble in water compared to alcohols since the sulfhydrl group forms weaker hydrogen bonds with water molecules; while short chains can be slightly soluble, longer chains are mostly insoluble

Density of Thiols

Thiols are generally less dense than water and their density increases with larger alkyl group

Uses of Thiols

fragrance, antioxidants, biochemistry & medicine, reagents, and plastics & rubber

Thiols in Biochemistry

Thiols play a vital role in biological systems, especially in forming and breaking disulfide bonds in proteins (e.g., cysteine and cystine).

Thiols in the Industry

they are ssed as odorants (ethyl mercaptan in natural gas) and in the production of polymers.

Thiols in Medicinal Chemistry

Thiols are used in some drugs and as intermediates in pharmaceutical synthesis.