H Lundbeck AS v Norpharma SPA & Ors

Justin Turner QC and Dominic Hughes (instructed by Wragge & Co LLP) for the Claimant and Part 20 Defendants Andrew Lykiardopoulos (instructed by Cumberland Ellis) for the Second Defendant Hearing dates: 16th-18th; 21st and 23rd-24th March 2011 ____________________

i) Oleum is the common name for a mixture of sulphur trioxide (SO 3 ) and sulphuric acid (H 2 SO 4 ). It can exist with any amount of SO 3 , although pure SO 3 would not be called oleum.

ii) Oleum was commercially available in various SO 3 concentrations ranging from 15 to 80% SO 3 . Those that the process chemist would have on the laboratory shelf might be in the range 20-30%.

iii) Pure SO 3 and oleum are both hazardous chemicals. Both are used very widely in the production of detergents, plastics and dyes. Both chemicals must be treated with care because they produce a corrosive mist containing droplets of H 2 SO 4 . Overall, as Dr Scott said, oleum would be regarded as a less hazardous reagent than SO 3 , but this is a matter of degree.

iv) SO 3 is a powerful dehydrating agent. When it reacts with water it forms sulphuric acid so that water is mopped up from the reaction. So pure SO 3 will become oleum if reacted with less than one mole equivalent of water.