Hi:

 

According to http://en.wikipedia.org/wiki/Thiol#Acidity "Relative to the alcohols, thiols are fairly acidic"

 

Does this mean all thiols have a pH below 7?

 

 

Thanks,

 

Green Xenon

No, what it means is that thiols are more likely to donate their proton (forming thiolate I think).

 

Thiols have a relatively high pka (for cysteine it's about 8.37) which means at pH higher than that, the thiol will donate it's proton, acting like an acid according to the Lowry Bronstedt model.

 

Hope this helps

In biological systems, a large portion of thiols (e.g. PKS and FAS systems) is deprotonated.

 

Thiols are more acidic because the sulphur based anion is more stable because it is a larger atom than the corrosponding alcohol.