There is an extensive article on smoke, wood and combustion on Amazingribs by MeatHead. Here is the address (not sure this violates the link rules): amazingribs.com/more-technique-and-science/grill-and-smoker-setup-and-firing/what-you-need-know-about-wood-smoke-and.
Meathead writes (apparently quoting Dr. Blonder), “Smoke includes as many as 100 compounds in the form of microscopic solids including char, creosote, ash, and phenols, as well as combustion gases that include carbon monoxide, carbon dioxide, nitric oxide, syringol, and liquids such as water vapor and syringol, an oil.â€
What happens to them when they’re exposed to searing heat in the direct-zone? One at a time–
Char . . . . . . . . . . . . . . It’s what’s left behind if wood is burned without adequate oxygen. Wood char is charcoal. Searing the meat will burn off the char.
Creosote. . . . . . . . . . . It burns as anyone who’s had a chimney fire will tell you. So, it burns off during searing.
Ash. . . . . . . . . . . . . . . It’s not combustible. It stays behind after searing.
Phenols . . . . . . . . . . . Phenols will sublimate and boil off at direct-zone temperatures.
Carbon monoxide. . . . It’s a gas. If it hangs around the meat, it’ll burn and become carbon dioxide.
Carbon dioxide. . . . . . It’s a gas. I doubt that it stays with the meat but if it does, it’s without odor or taste.
Nitric oxide . . . . . . . . It’s a gas. It’ll burn and become nitrogen dioxide.
Syringol. . . . . . . . . . . It ignites at about 285°. The direct zone will burn it.
Syringol oil . . . . . . . . It's a mix of syringol and water. The water evaporates and the syringol burns.
So, smoke flavor sitting on the meat’s surface is hit with our direct zone’s 1,000° heat and all but ash boils or burns off.
Interestingly, wood ash and water make caustic lye, potassium hydroxide. It’s not likely that we get much lye in a bite, but I wonder…
Searing in a frying pan won’t be at 1,000°, in fact I try to avoid searing by browning our steaks at much lower temperatures.