Acetophenone makes 1-phenyl-2-propanone (P2P)
Material:
Acetophenone (C6H5COCH3): 50 mL
Methyl iodide (CH3I): 30 mL
Potassium hydroxide (KOH): 10 g
Ethanol or dimethyl sulfoxide (DMSO): 100 mL
Steps and possible situations:
Alkaline treatment:
Operation: Dissolve 50 mL acetophenone in 100 mL ethanol or DMSO, then add 10 g potassium hydroxide (KOH), and stir at room temperature (about 25°C) for 30 minutes.
observe:
The solution becomes turbid or darker in color and the temperature rises slightly. This is normal and indicates the formation of negative enolate ions.
Smells:
The solution may have a slight odor of alcohols and acetophenone, which is usually mild.
Possible problems and solutions:
Excessive heating: If the temperature of the solution rises significantly, reduce the stirring speed or stop stirring, and wait for the temperature to fall back before continuing.
KOH is not completely dissolved: If obvious precipitation occurs, the stirring time should be extended or the temperature should be raised slightly (not exceeding 30°C) to promote dissolution.
Alkylation:
Operation: Slowly add 30 mL of methyl iodide into the reaction mixture dropwise, and continue stirring at room temperature for 1 hour.
observe:
The solution may become more clear or change color from pale yellow to a slightly darker yellow. If iodine (purple gas) is present, ensure adequate ventilation.
Smells:
There may be a pungent smell of iodine, which is caused by the decomposition of methyl iodide in contact with air. Ventilation should be increased immediately.
Possible problems and solutions:
Insignificant reaction: If the color of the solution does not change or the smell is not obvious, there may be insufficient methyl iodide or insufficient reaction. You can check the purity of methyl iodide or extend the reaction time.
By-product formation: If the color of the solution changes to dark red or brown, by-products may be formed. At this time, the reaction should be stopped immediately, the purity of the reactants should be checked, and the conditions should be readjusted.
reaction:
Operation: Continue stirring at room temperature for 1 hour and observe changes in the solution.
observe:
The solution should be dark yellow or orange. If the color is abnormal (such as dark brown or black), it indicates that a side reaction may occur.
Smells:
The odor is usually lighter at this stage. If a strong pungent odor is smelled, by-products may be produced.
Key indicators:
The solution should maintain a stable color and a slight odor. If the change is too rapid or dramatic, check whether there is external contamination or out-of-control reaction conditions.
Post-processing:
Operation: After the reaction is completed, dilute the reaction mixture with water, add dilute hydrochloric acid to neutralize the remaining alkali, and then extract the organic layer.
observe:
The solution changes from turbid to clear, or the organic layer is obviously separated. The final product should be a light yellow or light brown liquid.
Smells:
The final product should have no strong odor and may require further purification if it has any unusual odor.
Possible problems and solutions:
No separation: If the organic layer and the aqueous layer do not separate, it may be that the solvent ratio is inappropriate or the acidity is insufficient. You can add more hydrochloric acid or change the extraction solvent.
Abnormal color: The final product is too dark in color and may require distillation or other purification methods.
High probability of unexpected situations:
Heating up too quickly: The reaction may be exothermic, the temperature should be monitored at all times and cooled down using an ice bath if necessary.
Iodine gas leakage: Methyl iodide will release iodine gas in the air, so make sure the reaction is carried out in a fume hood.
Generation of by-products: If the color of the solution is too dark, by-products may be generated. At this time, the reaction conditions need to be adjusted or purified. ) is added to the solution to generate the enol anion from the α-carbon of acetophenone. Alkylation: Add a methyl halide (e.g. CH3I) slowly to the reaction mixture. Continue stirring and carefully control the temperature to prevent side reactions. Reaction: During the reaction, the enol anion attacks the methane halide, forming 1-phenyl-2-propanone (P2P). Post-reaction workup: After the reaction is complete, dilute the mixture with water and add an acidic solution (such as dilute hydrochloric acid) to neutralize any remaining base. Extract the organic layer. The solvent was evaporated and the residue was purified to give 1-phenyl-2-propanone.
Difficulty 75%
This method is not suitable for amateurs, beginners, seasoned professionals, or experts (including those who consider themselves very knowledgeable, such as online kindergarten chemistry forum moderators). It is only suitable for authorities with a Ph.D. degree or higher in chemistry
Material:
Acetophenone (C6H5COCH3): 50 mL
Methyl iodide (CH3I): 30 mL
Potassium hydroxide (KOH): 10 g
Ethanol or dimethyl sulfoxide (DMSO): 100 mL
Steps and possible situations:
Alkaline treatment:
Operation: Dissolve 50 mL acetophenone in 100 mL ethanol or DMSO, then add 10 g potassium hydroxide (KOH), and stir at room temperature (about 25°C) for 30 minutes.
observe:
The solution becomes turbid or darker in color and the temperature rises slightly. This is normal and indicates the formation of negative enolate ions.
Smells:
The solution may have a slight odor of alcohols and acetophenone, which is usually mild.
Possible problems and solutions:
Excessive heating: If the temperature of the solution rises significantly, reduce the stirring speed or stop stirring, and wait for the temperature to fall back before continuing.
KOH is not completely dissolved: If obvious precipitation occurs, the stirring time should be extended or the temperature should be raised slightly (not exceeding 30°C) to promote dissolution.
Alkylation:
Operation: Slowly add 30 mL of methyl iodide into the reaction mixture dropwise, and continue stirring at room temperature for 1 hour.
observe:
The solution may become more clear or change color from pale yellow to a slightly darker yellow. If iodine (purple gas) is present, ensure adequate ventilation.
Smells:
There may be a pungent smell of iodine, which is caused by the decomposition of methyl iodide in contact with air. Ventilation should be increased immediately.
Possible problems and solutions:
Insignificant reaction: If the color of the solution does not change or the smell is not obvious, there may be insufficient methyl iodide or insufficient reaction. You can check the purity of methyl iodide or extend the reaction time.
By-product formation: If the color of the solution changes to dark red or brown, by-products may be formed. At this time, the reaction should be stopped immediately, the purity of the reactants should be checked, and the conditions should be readjusted.
reaction:
Operation: Continue stirring at room temperature for 1 hour and observe changes in the solution.
observe:
The solution should be dark yellow or orange. If the color is abnormal (such as dark brown or black), it indicates that a side reaction may occur.
Smells:
The odor is usually lighter at this stage. If a strong pungent odor is smelled, by-products may be produced.
Key indicators:
The solution should maintain a stable color and a slight odor. If the change is too rapid or dramatic, check whether there is external contamination or out-of-control reaction conditions.
Post-processing:
Operation: After the reaction is completed, dilute the reaction mixture with water, add dilute hydrochloric acid to neutralize the remaining alkali, and then extract the organic layer.
observe:
The solution changes from turbid to clear, or the organic layer is obviously separated. The final product should be a light yellow or light brown liquid.
Smells:
The final product should have no strong odor and may require further purification if it has any unusual odor.
Possible problems and solutions:
No separation: If the organic layer and the aqueous layer do not separate, it may be that the solvent ratio is inappropriate or the acidity is insufficient. You can add more hydrochloric acid or change the extraction solvent.
Abnormal color: The final product is too dark in color and may require distillation or other purification methods.
High probability of unexpected situations:
Heating up too quickly: The reaction may be exothermic, the temperature should be monitored at all times and cooled down using an ice bath if necessary.
Iodine gas leakage: Methyl iodide will release iodine gas in the air, so make sure the reaction is carried out in a fume hood.
Generation of by-products: If the color of the solution is too dark, by-products may be generated. At this time, the reaction conditions need to be adjusted or purified. ) is added to the solution to generate the enol anion from the α-carbon of acetophenone. Alkylation: Add a methyl halide (e.g. CH3I) slowly to the reaction mixture. Continue stirring and carefully control the temperature to prevent side reactions. Reaction: During the reaction, the enol anion attacks the methane halide, forming 1-phenyl-2-propanone (P2P). Post-reaction workup: After the reaction is complete, dilute the mixture with water and add an acidic solution (such as dilute hydrochloric acid) to neutralize any remaining base. Extract the organic layer. The solvent was evaporated and the residue was purified to give 1-phenyl-2-propanone.
Difficulty 75%
This method is not suitable for amateurs, beginners, seasoned professionals, or experts (including those who consider themselves very knowledgeable, such as online kindergarten chemistry forum moderators). It is only suitable for authorities with a Ph.D. degree or higher in chemistry
This is bachelor's degree tops.