21. Organic synthesis
A section of Chemistry, 9701
Listing 10 of 83 questions
A series of experiments is carried out in which the reagent shown at the top of the column of the table is mixed, in turn, with each of the reagents at the side. Complete the following table by writing in each box the formula of any gas produced. Write x in the box if no gas is produced. The fi rst column has been completed as an illustration. H2O OH CO2H OH Na H2 KOHx Na2CO3x Compound C is responsible for the pleasant aroma of apples. It can be prepared from phenol by the following 3-step synthesis. OH OH C A CH3 H3C CH3 step OH C B CH3 H3C CH3 step O O C C CH3 CH3 H3C CH3 step The only by-product of step 1 is HCl. Suggest the reagent that was used to react with phenol to produce compound A. What type of reaction is occurring in step 2? What reagents and conditions are required for step 3? State the reagent and conditions needed to convert C back to B, the reverse of step 3. Either compound A or compound B, or both, react with the following reagents. For each reagent draw the structure of the organic product formed with A, and with B. If no reaction occurs, write ‘no reaction’ in the relevant box. reagent and conditions product with A product with B an excess of Br2heat with HBr pass vapour over heated Al 2O3 heat with acidifi ed K2Cr2O7 Choose one of the above reactions to enable you to distinguish between A and B. State below the observations you would make with each compound. reagent observation with A observation with B
9701_s13_qp_41
THEORY
2013
Paper 4, Variant 1
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A series of experiments is carried out in which the reagent shown at the top of the column of the table is mixed, in turn, with each of the reagents at the side. Complete the following table by writing in each box the formula of any gas produced. Write x in the box if no gas is produced. The fi rst column has been completed as an illustration. H2O OH CO2H OH Na H2 KOHx Na2CO3x Compound C is responsible for the pleasant aroma of apples. It can be prepared from phenol by the following 3-step synthesis. OH OH C A CH3 H3C CH3 step OH C B CH3 H3C CH3 step O O C C CH3 CH3 H3C CH3 step The only by-product of step 1 is HCl. Suggest the reagent that was used to react with phenol to produce compound A. What type of reaction is occurring in step 2? What reagents and conditions are required for step 3? State the reagent and conditions needed to convert C back to B, the reverse of step 3. Either compound A or compound B, or both, react with the following reagents. For each reagent draw the structure of the organic product formed with A, and with B. If no reaction occurs, write ‘no reaction’ in the relevant box. reagent and conditions product with A product with B an excess of Br2heat with HBr pass vapour over heated Al 2O3 heat with acidifi ed K2Cr2O7 Choose one of the above reactions to enable you to distinguish between A and B. State below the observations you would make with each compound. reagent observation with A observation with B
9701_s13_qp_43
THEORY
2013
Paper 4, Variant 3
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Menthol and menthone, the main constituents of oil of peppermint, can be made synthetically from thymol by the following route. I OH II OH thymol menthol menthone O State the type of reaction of • reaction I, • reaction II. Suggest one test for each of the three compounds that would give a positive result with the stated compound but a negative result with both the other two compounds. thymol test observation menthol test observation menthone test observation
9701_w10_qp_43
THEORY
2010
Paper 4, Variant 3
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Questions Discovered
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