最苦的物质是什么？ What is the most bitter compound?

The most bitter chemical compound is commonly believed to be N-[(2-[2,6-Dimethylphenyl)amino]-2-oxoethyl]-N,N-diethylbenzenemethanaminium benzoate [3734-33-6]. Fortunately, no one goes around using that name! It's usually called Bitrex or Denatonium Benzoate. You'll find it added to toxic liquids to deter people and pets from drinking them. For example, it is commonly added to methyl alcohol (methanol), bathroom cleaner, shampoo, soap, rat poison, nail polish remover and antifreeze. It's added to insulation to prevent rodents from chewing on wiring. It's also used in products applied to skin/fingernails to help keep people from biting their nails or sucking their thumbs. Now you know!