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Thiols

A thiol is a compound that contains the –SH functional group, which is the sulfur analogue of a hydroxyl or alcohol group.

Why this substance is hazardous?​

Thiols or mercaptan, although toxic are often not dangerous in the quantities used in experiments. However, thiols are odorants and are detectable to the human nose at as little as 2-parts per billion. At these concentrations, there are unlikely to cause chronic health problems but are classified as offensive due to the stench. This means that;​

  • ​It is against the Environment Act to release them as the smell itself is considered a statutory nuisance ​
  • The smell can cause some people to react adversely, common reactions are headaches and nausea ​
  • Due to uses of thiols as an additive to natural gas supplies, accidental release can cause widespread disruptions as it can be confused as a leak from the supply.​

Uses​

The most well-known use for thiols is as the odour in natural gas, they feature heavily in research due to their biological importance and thiols can be used to make disulphides and sulphonic acids.
B-Mercaptoethanol is an antioxidant.

Recommended control measures​

Minimise the risk of exposure

  • Always assess where the work is going to happen, thiols usually have high volatility so vapour will be produced.​
  • Do not work directly in a fume cupboard without filtration, either on the fume cupboard or on the experiment, as the smell will just be transported rather than removed.​

​Storage

Due to the volatility, store in a manner that will expect vapour to be produced and controlled ​

Use

  • Always inform the people working in the area and the department that works with thiols is to go ahead, in case of accident release.​
  • When possible ensure that all thiol vapour is caught and re-oxidised at the source. ​

Health surveillance ​

None.

Chemical safety library

> Read more about control measures for chemicals in our chemical safety library 

Other smelly chemicals ​

Chemicals that could be classed as​ statutory nuisances and should ​ follow the same control measures if​ used or produced​​:

  • Fruit fly food – Phenolic compounds​
  • Autoclaved culture plates (meat and blood)​
  • Trans-4,5- epoxy-E-2-decenal​
  • Formaldehyde​
  • Cadaverine – decarboxylated lysine​
  • n-Butanol​
  • Selenium and tellurium compounds (like sulphur but lower on the periodic table)​
  • Pyridine​
  • Terpenes and terpenoids (odour from cannabis) ​
  • Anything smelly produced that is unreasonable and substantially interferes with the use of a work area at UCL​

Last updated: Tuesday, June 23, 2020

Further guidance

> Working with controlled chemicals
> Safety Data Sheets ​​
> Risk Assessment
> Working safely with hazardous chemicals

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