14.2. Alkenes
A subsection of Chemistry, 9701, through 14. Hydrocarbons
Listing 10 of 191 questions
Three alkenes, X, Y and Z, have the same molecular formula. Describe what is seen when aqueousbromine is added to X. X, Y and Z are reacted separately with hot, concentrated, acidified manganate(ions until no further reaction occurs. The carbon-containing products are shown in the table. alkene carbon-containing products X CO2 + (CH3)2CO Y CO2 + CH3CH2CO2H Z CH3CO2H Draw the structures of X, Y and Z. X Y Z  Deduce the molecular formula of X, Y and Z. The structures of V and W are shown. CH3(CH2)2CH2OH (CH3)3COH V W Name the class of compound that V and W each belong to. V W  V and W both react with sodium metal. Write an equation for the reaction of V with sodium metal. Name a reagent used to distinguish V from W. Describe any observations. reagent observations with V observations with W  
9701_s19_qp_23
THEORY
2019
Paper 2, Variant 3
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By reference to the formation of σ and π bonds, describe and explain the shape of a benzene molecule, C6H6. 2,3-dimethylphenylamine can be prepared from 1,2-dimethylbenzene in two steps as shown. 1,2-dimethylbenzene CH3 CH3 M CH3 CH3 NO2 2,3-dimethylphenylamine CH3 CH3 NH2 HNO3 / H2SO4 step 1 step 2 Step1 is catalysed by H2SO4. Write an equation to show how H2SO4 generates the electrophile during step1. Draw the mechanism of the reaction between this electrophile and 1,2-dimethylbenzene to form M. Include all relevant curly arrows and charges. intermediate CH3 CH3 M CH3 CH3 NO2  Write an equation to show how the H2SO4 catalyst is reformed. For step2, suggest the reagents and conditions and name the type of reaction. ● reagents and conditions ● type of reaction  The drug mefenamic acid can be made using 2,3-dimethylphenylamine in an excess of 2‑chlorobenzoic acid. 2,3-dimethylphenylamine CH3 CH3 2-chlorobenzoic acid mefenamic acid CO2H CO2H Cl + + HCl NH2 CH3 CH3 N H Deduce the molecular formula of mefenamic acid. Name the functional groups, apart from the benzene ring, in mefenamic acid. Calculate the maximum mass of mefenamic acid that could be formed from 5.00 g of 2,3‑dimethylphenylamine in this reaction. Give your answer to three significant figures.  mass of mefenamic acid = g The position of substitution in the electrophilic substitution of arenes can be explained based on the stability of the intermediate cations formed in the first step. The example given involves the bromination of methylbenzene. methylbenzene CH3 CH3 + CH3 3-position 2-position 4-position Br H Br H CH3 + + Br H Use this information and your knowledge about the stability of cations to suggest why the CH3 group directs incoming electrophiles to the 2- and 4-positions in preference to the 3-position. 
9701_s19_qp_42
THEORY
2019
Paper 4, Variant 2
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The reaction sequence shows how ethene, C2H4, can be converted into other organic molecules. C2H4 W reaction 1 reaction 2 reaction 6 reaction 3 reaction 4 heat with dilute acid OH reaction 5 O N HO Cl NH2 Complete the table to give ● ● the name of the reaction mechanisms of reactions 1 and 6 ● ● the reagents and conditions required for reactions 1, 2 and 6. reaction name of mechanism name of reagents and conditions  In reaction3 the organic molecule reacts with HCN and a KCN catalyst. Complete the diagram to show the mechanism of the reaction occurring. Include all relevant dipoles, lone pairs and curly arrows in your answer. C C C O CN H H3C H3C O H C OH CN H3C H H – C N N – C N –  Name the functional groups present in the product of reaction3. Draw the structure of the organic molecule W formed in reaction4.  
9701_s20_qp_22
THEORY
2020
Paper 2, Variant 2
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Questions Discovered
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