14. Hydrocarbons
A section of Chemistry, 9701
Listing 10 of 313 questions
Bromine reacts with butane in the presence of ultraviolet light to form bromobutane. Two structural isomers with the molecular formula C4H9Br are produced during this reaction. Draw the two structural isomers and state the systematic name of each isomer. structural isomer 1 name structural isomer 2 name  Identify the type of structural isomerism shown in . Halothane is an anaesthetic. F C F F C halothane Cl Br H Identify the chiral centre in halothane and mark it with an asterisk (*). When halothane reacts in ultraviolet light, homolytic fission occurs and the C–Br bond is broken. Construct an equation to show the homolytic fission of halothane, CF3CHBrCl. Complete Fig.4.2 to show the arrangement of electrons in a bromine atom using the electrons in boxes notation. 3d 4p 4s  X is an addition polymer. Cl X n Draw the monomer of X.  Suggest one reason why the disposal of items made from X is difficult. 
9701_s22_qp_22
THEORY
2022
Paper 2, Variant 2
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Compound W, CH2=CHCN, is used to make an addition polymer which is present in carbon fibres. Draw one repeat unit of the addition polymer of W. CH3CHO is used in a two-step synthetic route to form W, as shown in . In step 1, CH3CHO is heated with HCN in the presence of KCN. CH3CHO CH3CH(OH)CN CH2=CHCN step 1 step 2 W Name the mechanism for the reaction in step 1 in . Complete to show the mechanism for the reaction in step 1. Include all products, charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. O H CH3 C N C Suggest a suitable reagent and conditions for step 2 in . shows the infrared spectrum of W, CH2=CHCN. wavenumber / cm–1 S T transmittance / % 50 Table 6.1 bond functional groups containing the bond characteristic infrared absorption range (in wavenumbers) / cm–1 C–O hydroxy, ester 1040–1300 C=C aromatic compound, alkene 1500–1680 C=O amide carbonyl, carboxyl ester 1640–1690 1670–1740 1710–1750 C≡N nitrile 2200–2250 C–H alkane 2850–2950 N–H amine, amide 3300–3500 O–H carboxyl hydroxy 2500–3000 3200–3600 Use Table 6.1 to identify the bonds responsible for the absorptions marked S and T on . S T Molecules of W, CH2=CHCN, do not show stereoisomerism. Describe stereoisomerism. Describe the two essential features of an alkene molecule that cause it to show geometrical stereoisomerism. Molecules of CH3CH(OH)CN exist as a pair of optical isomers. Draw three-dimensional diagrams in the boxes to show the optical isomers of CH3CH(OH)CN. isomer 1 isomer 2 Propanenitrile is heated with hydrogen gas and a platinum catalyst. The only product is propylamine. Construct an equation for this reaction. Propylamine can also be formed in a two-step synthesis from propan-1-ol, as shown in . CH3CH2CH2OH CH3CH2CH2Cl CH3CH2CH2NH2 step 1 SOCl 2 step 2 Name the type of reaction in step 1 in . Identify the reagent and conditions for step 2 in .
9701_s23_qp_23
THEORY
2023
Paper 2, Variant 3
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313