21. Organic synthesis
A section of Chemistry, 9701
Listing 10 of 83 questions
describes a sequence of reactions that can be used to produce a food additive, compound Y, from CH3CH2Cl . CH3CH2Cl CH3CH2CN CH3CH2COOH step 1 X Y step 2 dilute acid step 3 CaState the reagent and conditions for step 1 in . Give the systematic name of X. Identify the type of reaction that occurs when dilute acid is added to X in step 2. In step 3, Y and a gas are produced. Construct an equation for step 3. CH3CH2COOH can also be formed from propan-1-ol and potassium dichromate(. State the conditions required. Complete Table 3.1 to show the number of sigma bonds (σ ) and pi bonds (π) present in a molecule of X. Table 3.1 type of bond number of bonds in X sigma (σ ) pi (π)
9701_s23_qp_22
THEORY
2023
Paper 2, Variant 2
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4-nitromethylbenzene can be prepared via an electrophilic substitution reaction as shown. CH3 conc. HNO3 conc. H2SO4 methylbenzene CH3 NO2 H intermediate T CH3 NO2 4-nitromethylbenzene This reaction also forms an isomer of 4-nitromethylbenzene as a by-product. Draw the structure of this by-product. Write an equation for the reaction between HNO3 and H2SO4 that forms the electrophile for this reaction. Describe how the structure and bonding of the six-membered ring in intermediateT differs from that in methylbenzene. Benzocaine is used as a local anaesthetic. It can be synthesised from 4-nitromethylbenzene by the route shown. CH3 NO2 step 1 CH3 NH2 CH3 NHCOCH3 step 2 CO2CH2CH3 NH2 step 5 CO2H NH2 benzocaine W CO2H NHCOCH3 step 4 step 3 4-nitromethylbenzene Give the systematic name of compound W. Suggest the reagents and conditions for steps 1– 5. step 1 step 2 step 3 step 4 step 5 Suggest how the basicity of benzocaine would compare to that of ethylamine. Explain your answer. A sample of benzocaine, shown below, was analysed by proton NMR and carbon-13 NMR spectroscopy. Predict the number of peaks that would be seen in the carbon-13 NMR spectrum. Benzocaine was dissolved in CDCl 3 and the proton NMR spectrum of this solution was recorded. δ / ppm CO2CH2CH3 NH2 benzocaine Suggest why CDCl 3 and not CHCl 3 is used as the solvent when obtaining a proton NMR spectrum. Use the Data Booklet and the spectrum in to complete the table for the proton NMRspectrum of benzocaine. The actual chemical shifts, δ, for the four absorptions have been added. δ / ppm group responsible for the peak number of 1H atoms responsible for the peak splitting pattern 1.2 3.5 5.5 7.1–7.4 multiplet Explain the splitting pattern for the absorption at δ1.2 ppm. The proton NMR spectrum of benzocaine dissolved in D2O was recorded. Suggest how this spectrum would differ from the spectrum in . Explain your answer. Benzocaine can also be used to synthesise the dyestuff S by the following route. step 1 step 2 NaOH, R S OH phenol CO2CH2CH3 NH2 benzocaine Suggest the reagents used for step 1. Suggest structures for compounds R and S and draw them in the boxes.
9701_w17_qp_41
THEORY
2017
Paper 4, Variant 1
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4-nitromethylbenzene can be prepared via an electrophilic substitution reaction as shown. CH3 conc. HNO3 conc. H2SO4 methylbenzene CH3 NO2 H intermediate T CH3 NO2 4-nitromethylbenzene This reaction also forms an isomer of 4-nitromethylbenzene as a by-product. Draw the structure of this by-product. Write an equation for the reaction between HNO3 and H2SO4 that forms the electrophile for this reaction. Describe how the structure and bonding of the six-membered ring in intermediateT differs from that in methylbenzene. Benzocaine is used as a local anaesthetic. It can be synthesised from 4-nitromethylbenzene by the route shown. CH3 NO2 step 1 CH3 NH2 CH3 NHCOCH3 step 2 CO2CH2CH3 NH2 step 5 CO2H NH2 benzocaine W CO2H NHCOCH3 step 4 step 3 4-nitromethylbenzene Give the systematic name of compound W. Suggest the reagents and conditions for steps 1– 5. step 1 step 2 step 3 step 4 step 5 Suggest how the basicity of benzocaine would compare to that of ethylamine. Explain your answer. A sample of benzocaine, shown below, was analysed by proton NMR and carbon-13 NMR spectroscopy. Predict the number of peaks that would be seen in the carbon-13 NMR spectrum. Benzocaine was dissolved in CDCl 3 and the proton NMR spectrum of this solution was recorded. δ / ppm CO2CH2CH3 NH2 benzocaine Suggest why CDCl 3 and not CHCl 3 is used as the solvent when obtaining a proton NMR spectrum. Use the Data Booklet and the spectrum in to complete the table for the proton NMRspectrum of benzocaine. The actual chemical shifts, δ, for the four absorptions have been added. δ / ppm group responsible for the peak number of 1H atoms responsible for the peak splitting pattern 1.2 3.5 5.5 7.1–7.4 multiplet Explain the splitting pattern for the absorption at δ1.2 ppm. The proton NMR spectrum of benzocaine dissolved in D2O was recorded. Suggest how this spectrum would differ from the spectrum in . Explain your answer. Benzocaine can also be used to synthesise the dyestuff S by the following route. step 1 step 2 NaOH, R S OH phenol CO2CH2CH3 NH2 benzocaine Suggest the reagents used for step 1. Suggest structures for compounds R and S and draw them in the boxes.
9701_w17_qp_43
THEORY
2017
Paper 4, Variant 3
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2-hydroxypropanoic acid can be synthesised in four steps from ethanoicacid. OH O ethanoic acid step 1 Cl O CN O O OH O OH OH O 2-hydroxypropanoic acid step 2 step 3 step 4 Suggest a reagent for step 2. Suggest reagents and conditions for steps 1 and 4. step 1 step 4  Compound R can be used in the synthesis of compound T as shown. step I warm step II LiAl H4 Cl NH2 O R S C5H9NO T Suggest the structures of S and T and draw them in the boxes. Name the type of reaction for stepI and stepII. step I step II  Compound R can be polymerised. Draw a section of this polymer showing two repeat units.  
9701_w18_qp_42
THEORY
2018
Paper 4, Variant 2
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Questions Discovered
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