https://youglish.com/search/raison%20d%27%C3%AAtre/all
Not exactly English, but it's in the dictionary. I don't know if I should be impressed that the first result actually sounded pretty reasonable or disappointed at how bad some of these pronunciations are.
Of course, the whole thing is gonna be "results may vary", I suppose... https://youglish.com/getcid/25032799/electrophoresis