In the process of making controlled substances, the chemical reactions involved are often highly dangerous, so special attention needs to be paid to prevent accidents. The following are some types of chemical reactions that require special attention and their preventive measures： ### 1. **exothermic reaction** -**Features**: A large amount of heat is released during the reaction, which may cause the temperature to rise rapidly and cause a runaway reaction. -**Preventive measures**： -Use a cooling system or ice bath to control the reaction temperature. -Slowly add the reactants to avoid severe exothermic effects. -Monitor the reaction temperature and set up an alarm system. ### 2. **Redox reaction** -**Features**: It involves electron transfer and may produce flammable and explosive gases or substances. -**Preventive measures**： -React in an inert gas (such as nitrogen or argon) environment. - Avoid using strong oxidizing agents in direct contact with reducing agents. - Ensure good ventilation to prevent gas accumulation. ### 3. **Polymerization reaction** -**Features**: Monomer molecules combine to form a polymer, which may be accompanied by severe exothermic and pressure increase. -**Preventive measures**： - Use appropriate initiators and catalysts to control the reaction rate. -Monitor the reaction pressure and temperature to prevent runaway. -Use explosion-proof equipment, such as explosion-proof membranes or safety valves. ### 4. **Acid-base neutralization reaction** -**Features**: Acid-base reactions are usually exothermic, which may cause the solution to boil or splash. -**Preventive measures**： -Slowly add acid or alkali to avoid violent reactions. - Use appropriate protective equipment, such as goggles and gloves. - Operate in a fume hood to prevent the release of harmful gases. ### 5. **Organic synthesis reaction** -**Features**: Flammable and explosive organic solvents and intermediates may be involved. -**Preventive measures**： -Use explosion-proof equipment and inert gas protection. -Avoid using highly volatile solvents or operating in fume hoods. - Strictly control the reaction conditions to prevent side reactions or out of control. ### 6. **High pressure reaction** -**Features**: When carried out under high pressure conditions, the container may break or explode. -**Preventive measures**： -Use a certified high pressure reactor. - Check the equipment regularly to ensure that it is intact. -Set up a pressure release device, such as a safety valve or rupture disc. ### 7. **Photochemical reaction** -**Features**: Carried out under light conditions, free radicals or other highly active substances may be produced. -**Preventive measures**： - Use appropriate filters to control the light intensity and wavelength. - React in an inert gas environment to prevent oxygen or other gases from participating in the reaction. - Monitor the reaction process to prevent side reactions or out of control. ### 8. **Catalytic reaction** -**Features**: The catalyst may accelerate the reaction rate, causing it to get out of control. -**Preventive measures**： - Select the appropriate catalyst and control its dosage and activity. -Monitor the reaction rate to prevent poisoning or inactivation of the catalyst. -Use appropriate cooling and stirring systems to ensure that the reaction proceeds evenly. ### 9. **Gas-liquid reaction** -**Features**: The gas reacts with the liquid, which may produce high pressure or gas release. -**Preventive measures**： - Use appropriate reaction vessels to ensure that they can withstand pressure. -Control the gas flow rate to avoid violent reactions. -Set up a gas absorption device to prevent the release of harmful gases. ### 10. **Synthesis of explosive substances** -**Features**: It involves high-energy compounds and can easily cause explosions. -**Preventive measures**： -Operate in a specially designed explosion-proof laboratory. - Use trace reagents to avoid large-scale reactions. - Strictly control the reaction conditions to avoid friction, impact or electrostatic sparks. ### Summary When performing any chemical reaction involving controlled substances, laboratory safety procedures must be strictly observed, appropriate personal protective equipment must be worn, and all equipment must be in good condition. In addition, a detailed emergency plan should be formulated so that it can respond quickly and effectively in the event of an accident. Through the above measures, the risk of accidents can be minimized and the experiment can be carried out safely.