18.1. Carboxylic acids
A subsection of Chemistry, 9701, through 18. Carboxylic acids and derivatives
Listing 10 of 132 questions
State and explain the relative acidities of ethanol and phenol. In the table below, give the reaction conditions for the formation of organic products D and E and draw their structures. OH phenol HNO3 Br2 D E reagent conditions structure HNO3 dilute, 5 °C D Br2 E Name the mechanism of the reaction forming compound E. Phenylamine reacts with aqueous bromine to give compound F. Describe the appearance of compound F. Phenylamine reacts with nitrous acid to form a diazonium salt. State the conditions for this reaction. The diazonium salt in reacts with an alkaline solution of phenol to produce a coloured compound, G. Draw the structure of G. Compound H is a primary amine which has three peaks in its carbon-13NMR spectrum. H3C CH3 CH2 NH2 C H CH2 compound H An isomer of H is another primary amine J which also has three peaks in its carbon-13NMR spectrum. Use this information to suggest the structure of J. Another isomer of H is the tertiary amine K. It has three peaks in its protonNMR spectrum. One of the peaks is a doublet. CH3 H3C CH3 CH3 N CH K Circle the protons responsible for the doublet.
9701_m16_qp_42
THEORY
2016
Paper 4, Variant 2
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Acyl chlorides are useful intermediates in organic syntheses. State a suitable reagent for converting carboxylic acids into acyl chlorides. Construct an equation for the reaction between ethanoic acid, CH3CO2H, and the reagent you have stated in . In the boxes provided draw the structures of the compounds formed when benzoyl chloride undergoes the following reactions. C2H5OH COCl I II A NH3 B Name the functional group in • compound A • compound B . What type of reaction is reaction II? Suggest suitable acyl chlorides to use in the following reaction. Draw their structures in the boxes provided. + H2N NH2 NH HN O O OH OH O O C E O O O n + D F Compound E dissolves in, but does not react with, cold water. Suggest the major type of intermolecular interaction that occurs between E and water. A solution of the diamine H2NCH2CH2NH2 in water has pH = 11 but a solution of E in water has pH = 7. Suggest why this is the case. What type of polymer is compound F?
9701_s10_qp_41
THEORY
2010
Paper 4, Variant 1
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The compound responsible for the hot taste of chilli peppers is capsaicin. Its molecular structure can be deduced by the following reaction scheme. capsaicin, C18H27NO3 C, C10H18O2 D, C6H10O4 E, C4H8O2 + + boil with H3O+ reaction 5 reaction 3 reaction 4 heat with KCN heat with concentrated acidified KMnO4 NH2 OCH3 HO F, C6H8N2 Br(CH2)4Br (CH3)2CHCH2OH reaction 1 reaction 2 Compounds C, D and E all react with Na2CO3. Answer the following questions. Suggest reagents and conditions for reaction 3. What type of reaction is reaction 4? Suggest reagents and conditions for reaction 5. Name the functional group in C that has reacted with hot concentrated acidifi ed KMnO4. Suggest the name of the functional group in capsaicin that has reacted in reaction 1. Work out structures for compounds C–F and capsaicin, and draw their structural formulae in the boxes opposite.
9701_w12_qp_41
THEORY
2012
Paper 4, Variant 1
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The compound responsible for the hot taste of chilli peppers is capsaicin. Its molecular structure can be deduced by the following reaction scheme. capsaicin, C18H27NO3 C, C10H18O2 D, C6H10O4 E, C4H8O2 + + boil with H3O+ reaction 5 reaction 3 reaction 4 heat with KCN heat with concentrated acidified KMnO4 NH2 OCH3 HO F, C6H8N2 Br(CH2)4Br (CH3)2CHCH2OH reaction 1 reaction 2 Compounds C, D and E all react with Na2CO3. Answer the following questions. Suggest reagents and conditions for reaction 3. What type of reaction is reaction 4? Suggest reagents and conditions for reaction 5. Name the functional group in C that has reacted with hot concentrated acidifi ed KMnO4. Suggest the name of the functional group in capsaicin that has reacted in reaction 1. Work out structures for compounds C–F and capsaicin, and draw their structural formulae in the boxes opposite.
9701_w12_qp_42
THEORY
2012
Paper 4, Variant 2
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CompoundB is a liquid with a fruity smell. O B O Br The reaction scheme shows how B can be made from ethanol, C2H5OH. O B O Br O HO O HO Br C2H5OH and H2SO4 C2H5OH reaction 2 reaction 3 reaction 1 Reaction1 is an oxidation reaction. Give the reagentand conditions required for reaction1. reagentconditions  Construct an equation to represent reaction1. Use to represent an oxygen atom from the oxidising agent in this reaction. Suggest the type of reaction that occurs in reaction2. H2SO4 acts as a homogeneous catalyst in reaction3. Explain why H2SO4 is described as homogeneous. Reaction2 needs to take place in the absence of water to prevent formation of compound C. O C HO OH If C is present in the reaction mixture of reaction3, a different compound, compoundD, will also form. CompoundD has two identical functional groups. The infrared spectrum of D shows strong absorptions at 1100 cm–1 and 1720 cm–1, but no absorption due to O–H bonds. Use the Data Booklet to identify the functional group present in D. Explain your answer as fully as you can. Some other reactions of C are shown. O C HO OH Na2CO3 E F (CH2OH)2 G (CH2Cl )2 SOCl 2 Draw the structure of E.  Suggest why NaBH4 is not a suitable reagent to make F, (CH2OH)2, from C. Explain your answer. Construct an equation for the reaction of (CH2OH)2 with SOCl 2 to form G, (CH2Cl )2. Explain why C is very soluble in water. 
9701_w21_qp_21
THEORY
2021
Paper 2, Variant 1
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Questions Discovered
132