Such catalysts accelerate reactions between reagents dissolved in immiscible solvents. More specific Coombs reagents or monoclonal antibodies can be used. Various organometallic and inorganic reagents are effective. Activating reagents include phosphoryl chloride and peptide coupling reagents. Both Grignard reagents and organolithium compounds behave as the R synthon. They are produced by chlorination of sulfonic acids using thionyl chloride and related reagents. Examples of Grignard reagents are phenylmagnesium bromide and ethylmagnesium bromide. Polar aprotic solvents are generally incompatible with strong bases, such as Grignard reagents or "t"-butyllithium. This makes aromatic compounds more prone to attacks by electrophilic reagents. Below are some common methods for preparing organolithium reagents. Alcohols, water, amines, thiols and many other reagents add to epoxides. Paraffin is unaffected by most common chemical reagents but burns readily. Some tin reagents are useful in organic chemistry. The most common commercial reagents for transfection of siRNA are Lipofectamine and Neon Transfection. Emulsion PCR takes place in microreactors containing all the necessary reagents for PCR.