How to extract (pure) nicotine from tobacco without all of the carcinogens?

That is exactly what: e-cigarettes do, or commercially available vaporizers. In e-cigs the nicotine is provided in a liquid form which is volatilized in a heating chamber electrically, releasing nicotine as a vapor without other elements. However, the oils, propellant, flavorings, preservatives and other chemicals have never been subjected to testing, and nobody knows what they do to people long-term. It is still bad.