3 Electrophilic addition

 

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3.4 Alkenes Page 2 - 3

Oxford Textbook Pages : 220 - 223

CGP Revision Guide Pages : 143 - 145

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Show Specification Ref : 3.3.4.2

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Question 1 / 5

AQA Jan 2011 Paper 2 Q7 do not write outside the box a the reaction of bromine with propane is similar to that of chlorine with methane three steps in the mechanism for the bromination of propane to form bromopropane are shown below step step step br br cid ch ch ch ch ch ch cid br br cid ch ch ch cid hbr ch ch ch br br cid a i name the type of mechanism in this reaction mark a ii give an essential condition for step to occur mark a iii name the type of step illustrated by steps and mark a iv in this mechanism a different type of step occurs in which free radicals combine name this type of step write an equation to show how hexane could be formed from two free radicals in the mechanism of this reaction type of step equation marks a v write an overall equation for the reaction between bromine and propane by the same mechanism to produce octabromopropane c br mark wmp jan chem do not write outside the box b bromine reacts with alkenes even though bromine is a non polar molecule b i explain why bromine molecules react with the double bonds in alkenes marks extra space b ii name the type of mechanism involved in this reaction mark b iii draw the structure of the compound with mr formed when penta diene h c chch ch ch reacts with an excess of bromine c two products are formed when propene reacts with hydrogen bromide draw the structure of the intermediate that leads to the formation of the major product in the reaction of propene with hydrogen bromide give the name of this type of intermediate structure of intermediate mark type of intermediate marks turn over wmp jan chem there are no questions printed on this page do not write on this page answer in the spaces provided wmp jan chem
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Question 2 / 5

AQA Jun 2010 Paper 2 Q2 do not write outside the box a a student carried out an experiment to study the rates of hydrolysis of some haloalkanes in the experiment two different haloalkanes were placed in separate test tubes containing silver nitrate solution the haloalkanes reacted with the water in the silver nitrate solution the student timed how long it took for the first appearance of the silver halide precipitate in each tube at a constant temperature this time was used to provide a measure of the initial rate of reaction the student obtained the following results time to form a precipitate s bromobutane iodobutane a i state the meaning of the term hydrolysis mark a ii state the colour of the precipitate formed when iodide ions react with silver nitrate and write the simplest ionic equation for this reaction colour of precipitate simplest ionic equation marks a iii use your knowledge of the reactions of halide ions with silver nitrate to suggest why the student did not include fluorobutane in this experiment marks wmp jun chem do not write outside the box b the student used the following enthalpy data to try to account for the different initial rates of hydrolysis of the haloalkanes used in part a the student deduced that the rate of hydrolysis of a haloalkane is influenced by the strength of the carbon halogen bond in the haloalkane bond enthalpy kj mol c br c i state how the experimental evidence enabled the student to make this deduction mark c the student had read that the reaction of water with haloalkanes was similar to the reaction of aqueous sodium hydroxide with haloalkanes and was an example of a nucleophilic substitution reaction c i state the meaning of the term nucleophile mark c ii when a hydroxide ion collides with a molecule of bromobutane the following reaction occurs ch ch ch ch br oh ch ch ch ch oh br outline the nucleophilic substitution mechanism for this reaction question continues on the next page marks turn over wmp jun chem do not write outside the box d the reaction of hydroxide ions with bromo methylpropane may occur by a different mechanism from the one in part c this different mechanism involves the formation of a carbocation d i complete the following equation by drawing the structure of the carbocation formed when the c br bond in bromo methylpropane is broken ch ch c br ch br mark d ii suggest one reason why this reaction occurs by a mechanism involving a carbocation but the reaction in part c ii does not mark wmp jun chem
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Question 3 / 5

AQA Jun 2014 Paper 2 Q7 do not write outside the box table gives the names and structures of some structural isomers with the molecular formula c h table name of isomer structure isomer pent ene ch ch chch ch isomer cyclopentane isomer methylbut ene ch chch ch isomer methylbut ene ch c chch isomer methylbut ene h c c ch ch ch a isomer exists as e and z stereoisomers a i state the meaning of the term stereoisomers marks a ii draw the structure of the e stereoisomer of isomer mark wmp jun chem do not write outside the box b a chemical test can be used to distinguish between separate samples of isomer and isomer identify a suitable reagent for the test state what you would observe with isomer and with isomer marks reagent observation with isomer observation with isomer c use table a on the data sheet when answering this question isomer and isomer have similar structures c i state the infrared absorption range that shows that isomer and isomer contain the same functional group mark c ii state one way that the infrared spectrum of isomer is different from the infrared spectrum of isomer mark question continues on the next page turn over wmp jun chem do not write outside the box d two alcohols are formed by the hydration of isomer draw the displayed formula for the alcohol formed that is oxidised readily by acidified potassium dichromate vi mark e isomer reacts with hydrogen bromide to give two structurally isomeric bromoalkanes e i name and outline a mechanism for the reaction of isomer with hydrogen bromide to give bromo methylbutane as the major product marks ch c chch hbr ch cbrch ch name of mechanism mechanism wmp jun chem do not write outside the box e ii the minor product in this reaction mixture is bromo methylbutane explain why this bromoalkane is formed as a minor product marks f name and outline a mechanism for the following reaction to form isomer state the role of the hydroxide ion in this reaction marks ch cbrch ch koh h c c ch ch ch kbr h o name of mechanism mechanism role of hydroxide ion turn over wmp jun chem
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Question 4 / 5

AQA Jun 2015 Paper 2 Q8 section b do not write outside the box answer all questions in the spaces provided consider the following scheme of reactions ch reaction ch h c c ch ch h c c chcl ch reaction ch ch ch reaction h c c ch nh ch ch a give the iupac name for compound p and that for compound q marks p q wmp jun chem do not write outside the box b the conversion of p into q in reaction uses hcl name and outline a mechanism for this reaction marks c the conversion of q into r in reaction uses nh name and outline a mechanism for this reaction marks question continues on the next page turn over wmp jun chem do not write outside the box d state the type of reaction shown by reaction identify a reagent for this reaction give one condition necessary for a high yield of product when q is converted into p marks e hydrogen bromide hbr could be used in the overall conversion of p into r instead of using hcl hydrogen bromide is made by the reaction of nabr with concentrated phosphoric acid concentrated sulfuric acid is not used to make hbr from nabr write an equation for the reaction of nabr with h po to produce hbr and na po only identify two toxic gases that are formed together with hbr when nabr reacts with concentrated h so state the role of h so in the formation of these two toxic gases marks wmp jun chem
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Question 5 / 5

AQA Jun 2016 Paper 2 Q9 do not write outside the box a alcohols can be prepared from alkenes in various ways on a laboratory scale a mixture of propan ol and propan ol can be prepared from propene in two steps in step propene reacts with cold concentrated sulfuric acid to form intermediate compounds in step the intermediate compounds react with water to form the mixture of alcohols name and outline the mechanism for the reaction between propene and concentrated sulfuric acid to form the intermediate compound which gives propan ol in step explain why propan ol is the major product of this preparation marks wmp jun chem do not write outside the box b on an industrial scale ethanol can be produced from ethene by direct hydration or from glucose by fermentation state the conditions for the direct hydration reaction state two advantages and two disadvantages of the fermentation method compared with the direct hydration method marks end of questions wmp jun chem
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