No perfect replacement for R-22 has been found in this galaxy.
Until now, we have all assumed we will never have to worry about the phaseout of R-22, because science will eventually come up with a solution. However, that just won't be the case here. For, as one DuPont scientist explained it, “If we want a new and better refrigerant, we will have to look for it in another galaxy. We already know of all the gases on earth and what properties we can combine. And all these potential refrigerants (other than HFCs) are toxic, flammable, or they don't have the other necessary properties for air conditioners.”