Donald Cram for Herbert Lindlar
Me: Is that you Herbert Lindlar?
Cram: Actually no, it is me, the famous chemist from UCLA Donald Cram. I know you could not find a photo of the real Dr. Lindlar, so you used my stylin’ photo here to channel him. It is an action shot, but why don’t I have any safety glasses on? Oops, don’t tell anyone. Dr. Lindlar was born in England, but he moved to Switzerland and completed his PhD in Chemistry there, then spent his long career as a chemist at Hoffman-LaRoche. He knew that alkynes are usually reduced all the way to alkanes with catalytic metals such as Pd or Pt in the presence of hydrogen. Dr. Lindlar predicted that if just the right catalyst poisons could be found, a catalyst formulation could be identified that was strong enough to reduce alkynes to alkenes in the presence of hydrogen, but then is not strong enough to reduce alkenes any farther. After trying many, many additives, Lindlar found that adding a molecule called quinoline along with some lead was perfect. The Lindlar catalyst formula in the presence of hydrogen adds two H atoms with syn addition geometry, so it gives cis alkenes from alkynes. Wacky stuff, the mechanism was only figured out recently.
Me: Fascinating, anything else?
Cram: Remember, Dr. Lindlar’s catalyst can reduce alkynes to cis alkenes. One more thing, Dr. Herbert Lindlar lived to be one hundred years old. And even though he lived so long, he somehow avoided having any pictures available on the internet! Crazy. Peace out, from here!
