• Sulfone 2 is a key intermediate in the synthesis of HESS, a novel VOC-free crosslinking monomer. 2 is prepared by oxidation of sulfide 1, itself obtained via nucleophilic addition of 4-bromothiophenol to 2-chloroethanol.
• A pilot facility had been identified for kilo-scale manufacture, however large-scale manufacturing issues had not been addressed as the client’s focus had been to produce small quantities for materials testing.

Customer Requirements

• For pilot manufacture, quantification of exotherms that might occur under normal and abnormal operating conditions for stages 1 and 2 was needed,
• An assessment of feasible manufacturing conditions based on physicochemical properties was also requested
• Stage 2 was known to be particularly exothermic. Hydrogen peroxide and perborate are strong oxidizing agents requiring special precautions; hydrogen peroxide can also decompose to form copious quantities of oxygen gas. Since the rate of decomposition increases with increasing temperature, it was paramount to understand how control of the process temperature could be achieved on large-scale
• In particular, accumulation of the peroxide species in solution could be potentially very dangerous and must be avoided.

Approach

• Reaction calorimetry was carried out on each of stages 1 and 2 and used to calculate ΔHr.
• Kinetic models based on the reaction chemistry were prepared and kinetic parameters were regressed to Qr data.
• Reaction models were combined with detailed reactor model based on the chosen pilot facilities in order to construct process models. These models were then used to calculate Maximum Temperature of the Synthesis Reaction under adiabatic conditions (MTSR) values and predict the effects of reagent accumulation under different scenarios
• A detailed process review based on laboratory procedures was also carried out. This entailed assessing the lab process according to key scale-up criteria (safety, permissibility, regulatory, environmental and economic factors).
• Process flow-sheets and material balances were also prepared to assist the pilot manufacturer with equipment selection.