When working with controlled substances, certain chemical reactions must be handled with caution to prevent accidents, explosions, or toxic releases. The following are some key chemical reactions that require special attention when working with controlled substances: 1. **High-energy reactions**: Reactions involving high-energy intermediates such as nitration, bromination, or chlorination can quickly get out of control and result in explosions. The Walden Synthesis, Xanthan Synthesis, and Soddy Reaction are all examples of high-energy reactions. 2. **STILL?? Reactions**: This reaction involves the addition of ozone (O3) to an olefin to form oxidized ozone, which can result in explosions or heat release. Safety precautions are essential when working with ozone or other highly reactive oxidizing agents. 3. **Catalytic hydrogenation reactions**: These reactions may involve high pressures and flammable gases such as hydrogen. The use of hydrogenating agents such as Raney nickel or palladium may introduce the risk of fire or explosion. 4. **Imine formation reactions**: These reactions may involve the use of strong bases such as diisopropylamine (DIPEA) or toxic reagents such as thalidomide. Caution and ventilation are essential when working with these reagents. 5. **Alkylation reactions**: These reactions involve the addition of an alkyl group to a molecule, which may involve the use of a strong nucleophile such as an alkyl lithium or a Grignard reagent. These reactions can be violent and may introduce a risk of fire or explosion. 6. **Phosphorylation reactions**: These reactions may involve the use of corrosive reagents such as phosphoric anhydride (POCl3), which presents a risk of burns, skin and eye irritation, and damage to equipment. 7. **Nitration reactions**: These reactions involve the addition of a nitro (NO2) group to a molecule, which may involve the use of a strong oxidizing agent such as nitric acid (HNO3) or nitrates. This may introduce a risk of fire, explosion, or toxic gas release. 8. **Grignard reactions**: These reactions involve the use of a Grignard reagent such as methylmagnesium bromide (CH3MgBr), which may be sensitive and unpredictable. 9. **Stereoselective reactions**: These reactions may involve the use of flammable or explosive materials such as alkyl metals such as lithium or magnesium, and caution is required when handling these reactants. 10. **Self-accelerating reactivity**: Certain reactions, such as nucleotide synthesis or Condrieu-Vig reactions, can rapidly self-accelerate due to exothermic or saturated conditions, leading to accidents or the release of hazardous materials. When handling controlled substances, you must: * Perform a thorough risk assessment * Follow established safety protocols and guidelines * Use personal protective equipment (PPE) * Ensure adequate ventilation in the laboratory * Monitor the temperature, pressure, and pH of the reaction * Have emergency equipment ready, such as fire extinguishers and emergency showers * Train operators about potential hazards and emergency procedures Always consult a safety expert, laboratory supervisor, or manufacturer documentation to ensure you understand the specific hazards and risks associated with potentially hazardous chemical reactions.