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14.2. Alkenes
A subsection of Chemistry, 9701, through 14. Hydrocarbons
Listing 10 of 191 questions
1,3-dimethylbenzene is a useful starting material for several commercially important compounds. The artifi cial ‘musk ketone’, A, is a perfume agent added to many cosmetics and detergents. It is made from 1,3-dimethylbenzene by the following route. 1,3-dimethylbenzene ‘musk ketone’ A step 1 step 2 step 3 O O O2N NO2 The only by-product of step 2 is HCl. Suggest the reagent that was used in this step. Suggest the type of reaction that is occurring during both step 2 and step 3. State the reagents and conditions needed for step 3. Suggest the structures of the two products formed when A is reacted with alkaline aqueous iodine. 1,3-dimethylbenzene is also a starting material for the synthesis of the polymer Nomex, used in fi reproof protective clothing worn by fi refi ghters, military pilots and racing car drivers. The polymer is made from 1,3-dimethylbenzene and 1,3-dinitrobenzene by the following route. 1,3-dimethylbenzene 1,3-dinitrobenzene step 1 step 3 Nomex step 2 HO2C H2N NH2 O2N NO2 CO2H Draw the structure of one repeat unit of Nomex in the box above. What type of polymer is Nomex? Suggest the by-product formed during step 3. Suggest reagents and conditions for step 2. Suggest how and why the properties of the polymer might change if some of the diamine monomer were replaced with 1,3,5-triaminobenzene. NH2 NH2 1,3,5-triaminobenzene H2N
9701_s15_qp_41
THEORY
2015
Paper 4, Variant 1
View
Long chain alkanes such as 4-methylheptane can be ‘cracked’ to produce shorter chain hydrocarbons. 4-methylheptane B C3H8 a mixture of C, D and E (isomers of C5H10) + State the conditions necessary for this reaction to take place. Suggest the structure of B. B Compounds C, D and E are isomers with the molecular formula C5H10. On heating with concentrated acidifi ed KMnO4, ● compound C gives CO2 and compound F (C4H8O2), ● D and E each give a 1 : 1 mixture of compounds G (C2H4O2) and H (C3H6O2). Suggest structures for compounds C - H. C D E F G H Name the type of isomerism shown between D and E. Propene, CH3CH=CH2, reacts with bromine to give 1,2-dibromopropane. How is this reaction usually carried out? State the type of reaction that is occurring here. Draw the mechanism of this reaction, including the structures of any intermediates, and any dipoles, lone pairs and curly arrows to show the movements of electrons.
9701_s15_qp_41
THEORY
2015
Paper 4, Variant 1
View
1,3-dimethylbenzene is a useful starting material for several commercially important compounds. The artifi cial ‘musk ketone’, A, is a perfume agent added to many cosmetics and detergents. It is made from 1,3-dimethylbenzene by the following route. 1,3-dimethylbenzene ‘musk ketone’ A step 1 step 2 step 3 O O O2N NO2 The only by-product of step 2 is HCl. Suggest the reagent that was used in this step. Suggest the type of reaction that is occurring during both step 2 and step 3. State the reagents and conditions needed for step 3. Suggest the structures of the two products formed when A is reacted with alkaline aqueous iodine. 1,3-dimethylbenzene is also a starting material for the synthesis of the polymer Nomex, used in fi reproof protective clothing worn by fi refi ghters, military pilots and racing car drivers. The polymer is made from 1,3-dimethylbenzene and 1,3-dinitrobenzene by the following route. 1,3-dimethylbenzene 1,3-dinitrobenzene step 1 step 3 Nomex step 2 HO2C H2N NH2 O2N NO2 CO2H Draw the structure of one repeat unit of Nomex in the box above. What type of polymer is Nomex? Suggest the by-product formed during step 3. Suggest reagents and conditions for step 2. Suggest how and why the properties of the polymer might change if some of the diamine monomer were replaced with 1,3,5-triaminobenzene. NH2 NH2 1,3,5-triaminobenzene H2N
9701_s15_qp_43
THEORY
2015
Paper 4, Variant 3
View
Long chain alkanes such as 4-methylheptane can be ‘cracked’ to produce shorter chain hydrocarbons. 4-methylheptane B C3H8 a mixture of C, D and E (isomers of C5H10) + State the conditions necessary for this reaction to take place. Suggest the structure of B. B Compounds C, D and E are isomers with the molecular formula C5H10. On heating with concentrated acidifi ed KMnO4, ● compound C gives CO2 and compound F (C4H8O2), ● D and E each give a 1 : 1 mixture of compounds G (C2H4O2) and H (C3H6O2). Suggest structures for compounds C - H. C D E F G H Name the type of isomerism shown between D and E. Propene, CH3CH=CH2, reacts with bromine to give 1,2-dibromopropane. How is this reaction usually carried out? State the type of reaction that is occurring here. Draw the mechanism of this reaction, including the structures of any intermediates, and any dipoles, lone pairs and curly arrows to show the movements of electrons.
9701_s15_qp_43
THEORY
2015
Paper 4, Variant 3
View
Questions Discovered
191