17. Carbonyl compounds
A section of Chemistry, 9701
Listing 10 of 304 questions
Explain why trichloroethanoic acid, CCl 3COOH, is more acidic than ethanoic acid, CH3COOH. Acyl chlorides are formed by reacting carboxylic acids with thionyl chloride, SOCl 2. Ethanedioyl chloride, (COCl )2, can be prepared by reacting ethanedioic acid, (COOH)2, with an excess of SOCl 2. Write an equation for this reaction. Samples of (COCl )2 are reacted separately with an excess of warm acidified KMnO4and with H2NCH2CH2NH2. The carbon‑containing product from the reaction with H2NCH2CH2NH2 has the molecular formula C4H6N2O2. Complete the boxes in to suggest the structure of the carbon‑containing product in each reaction. with warm acidified KMnO4with H2NCH2CH2NH2 A polyester can be synthesised from the reaction of (COCl )2 with ethane‑1,2‑diol, HOCH2CH2OH. Draw two repeat units of the polymer formed. Any functional groups should be displayed. Compound H, C6H10O3, reacts with alkaline I2to form yellow precipitate J but does not react with Na2CO3. The proton (1H) NMR spectrum of H in CDCl 3 is shown in . 4.0 3.0 2.0 chemical shift δ / ppm 1.0 Table 9.1 environment of proton example chemical shift range δ / ppm alkane –CH3, –CH2–, >CH– 0.9–1.7 alkyl next to C=O CH3–C=O, –CH2–C=O, >CH–C=O 2.2–3.0 alkyl next to aromatic ring CH3–Ar, –CH2–Ar, >CH–Ar 2.3–3.0 alkyl next to electronegative atom CH3–O, –CH2–O, –CH2–Cl 3.2–4.0 attached to alkene =CHR 4.5–6.0 attached to aromatic ring H–Ar 6.0–9.0 aldehyde HCOR 9.3–10.5 alcohol ROH 0.5–6.0 phenol Ar–OH 4.5–7.0 carboxylic acid RCOOH 9.0–13.0 alkyl amine R–NH– 1.0–5.0 aryl amine Ar–NH2 3.0–6.0 amide RCONHR 5.0–12.0 , , Identify yellow precipitate J. Complete Table 9.2 for the proton (1H) NMR spectrum of H, C6H10O3. Table 9.2 chemical shift δ / ppm splitting pattern number of 1H atoms responsible for the peak number of protons on adjacent carbon atoms 1.15 2.25 3.60 3.95 Suggest a structure for H, C6H10O3. , ,
9701_s24_qp_42
THEORY
2024
Paper 4, Variant 2
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The reaction scheme shows some reactions of [Co(H2O)6]2+. [Co(H2O)6]2+ CO3 2–[Co(H2O)4(OH)2] solution of A precipitate B reaction 1 reaction 3 reaction 2 excess NH3Write the formulae of the following species. A B  State a suitable reagent for reaction1. Write an equation for reaction2. Write an ionic equation for reaction3. Co2+ ions catalyse the oxidation of 2,3-dihydroxybutanedioate ions, C4H4O6 2–, to methanoate ions, HCO2 –, carbon dioxide and water. What property of transition elements allows Co2+ ions to act as a catalyst? Draw the structure of the 2,3-dihydroxybutanedioate ion.  Complete the equation for the oxidation of 2,3-dihydroxybutanedioate. Use for the oxidising agent in this reaction. C4H4O6 2– + ���������������������������������������������������������������������������������� Platin, Pt(NH3)2Cl 2, displays cis-trans isomerism. Draw the structures of these isomers. cis isomer trans isomer  Cis-platin is an effective anti-cancer drug. Describe the action of cis-platin in this role. The use of cis‑platin can cause side effects so carboplatin has been developed. Carboplatin can be synthesised from cis‑platin, Pt(NH3)2Cl 2, by replacing the two chloride ion ligands with a single cyclobutane‑1,1‑dicarboxylate ion ligand as shown. Pt(NH3)2Cl 2 + cis-platin O O O– O– 2– + 2Cl – cyclobutane-1,1-dicarboxylate ion carboplatin Suggest the structure for carboplatin and draw it in the box. 
9701_w18_qp_42
THEORY
2018
Paper 4, Variant 2
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Questions Discovered
304