What are mercaptans?

Mercaptans, also known as thiols, are a group of organic compounds with the general formula R-SH, where R is an alkyl or aryl radical. They are characterised by their unpleasant, pungent odour, which is often compared to rotten eggs or rotting vegetables. Mercaptans occur in small quantities, for example in natural gas, and are also used industrially in the plastics and pharmaceutical industries. Their intense odour makes them useful warning substances in the event of gas leaks.

Creation

Mercaptans are formed both naturally and industrially. Natural sources include the decomposition of organic material and certain biological processes. Industrially, mercaptans are released during the refining of crude oil and natural gas, in the manufacture of plastics and in the production of pesticides and pharmaceuticals.

Recognition

Mercaptans are very easy to recognise due to their pungent and unpleasant odour, often described as the smell of rotten eggs or rotting vegetables. Even the smallest quantities are perceptible, which is why they are used as a warning substance in natural gas. Mercaptans are colourless and can cause irritation on contact with the skin. Inhalation can cause headaches, nausea and respiratory irritation.

Limit values

In Germany, the limit values for mercaptan are regulated by the Technical Instructions on Air Quality Control (TA-Luft) and the occupational exposure limit values (OEL). The OEL for mercaptan is 0.5 ppm (parts per million) or 1 mg/m³. These limit values are intended to ensure that the concentrations in the workplace do not cause any damage to health.

Hazards

Health: Mercaptans can cause irritation on contact with the skin and cause headaches, dizziness and nausea if inhaled. In higher concentrations they can cause respiratory tract irritation, coughing and eye irritation. At high exposure levels, there is a risk of unconsciousness and respiratory arrest. Environment: Mercaptans can pollute the environment, especially through air pollution. They are capable of causing acid rain and can be toxic to fish and other aquatic organisms in water bodies. Economic damage: Improper handling and release of mercaptans can cause considerable costs due to necessary safety measures and claims for damages. In addition, production losses and increased employee illness rates can significantly impair the economic efficiency of a company.