The influence of water on the rates of 1,3-dipolar cycloaddition reactions: trigger points for exponential rate increases in water-organic solvent mixtures. Water-super versus water-normal dipolarophiles.

摘要: The nature of the rate enhancements caused by gradually increasing mole fraction water in solvent (from 0 to 1) for cycloaddition reactions pyridazinium-dicyanomethanide 1,3-dipole, 2, with dipolarophiles ethyl vinyl ketone (a water-super dipolarophile) and methyl acrylate water-normal organic solvents acetonitrile, acetone, methanol, ethanol, tert-butyl alcohol at 37 °C are explored. In each case as surpassed ca. 0.9, exponential were triggered. When methanol replaced water, smaller, no triggering effect was observed. dramatic enhancement triggered dipolarophile significantly reduced temperature raised range 29−64 °C. results suggest that a dominant hydrogen-bonding operates water-induced 1,3-dipolar well hydrophobic effect. h...