Thiol

Thiol is an organic compound that contains a sulfhydryl (–SH) group. The term "thiol" is derived from the Greek word for sulfur, "theion". Thiols are the sulfur analogue of alcohols (that is, sulfur takes the place of oxygen in the hydroxyl group of an alcohol), and the word is a portmanteau of "thio" + "alcohol", with the first word deriving from Greek θεῖον ("brimstone") + the second word as a back-formation from "alcohol". They are often referred to as mercaptans.

Structure and bonding

Thiols and alcohols have similar molecular structures. The major difference is the size of the sulfur atom, which is larger than the oxygen atom, and the strength of the C–S bond, which is weaker than the C–O bond.

Properties

Thiols are typically much more acidic than the corresponding alcohols, phenols, and carboxylic acids. The pKa of thiols is in the range of 8-10, whereas the pKa of ethanol is 16 and that of phenol is 10.

Occurrence

Thiols are found in the human body and are a component of certain proteins, including cysteine and glutathione. They are also found in garlic and onions.

Uses

Thiols are used in the production of rubber, oil recovery, and the manufacture of pharmaceuticals.

Safety

Thiols are toxic and have a strong odor. They can cause skin and eye irritation, and prolonged exposure can lead to lung damage.

See also

• Disulfide bond
• Thioether
• Organosulfur compounds

Thiol Resources
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