The Comparative Reaction Solvent Program at Gaylord Chemical Corporation systematically compares DMSO performance versus other common solvents in commercially important reactions. This project was undertaken to reinforce and expand the use of DMSO in discovery and process chemistry. Using established references from the chemical literature, our scientists test reaction systems to ascertain the yield, selectivity, and reaction rates of DMSO versus other solvents. We have thus far evaluated the performance of DMSO relative to standard solvents in the selected reactions shown below. We have found surprising yield advantages for DMSO in the Dieckmann Cyclization, Halex reaction, and Wittig reaction, to name specific examples. Thus, in the Dieckmann Cyclization, use of dimsyl ion in DMSO gave virtually quantitative yields of 2-carbethoxycyclopentanone, whereas the commercial process involving sodium metal in toluene resulted in only moderate yields of circa 70%.