2-(N-morpholino) ethanesulfonic acid CAS 4432-31-9
33695-250g

MES (2-(N-morpholino)ethanesulfonic acid) is a chemical compound that contains a morpholine ring.

It has a molecular weight of 195.2 g/mol and the chemical formula is C₆H₁₃NO₄S. 

MES is used as a buffering agent in biology and biochemistry. It has pK_a value of 6.15 at 20 °C. The pH (and pK_a at ionic strength I≠0) of the buffer solution changes with concentration and temperature, and this effect may be predicted using online calculators.^[2] MES is highly soluble in water.