2 Stereoisomerism

 

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4.1.3 alkenes Page 2 - 3

Oxford Textbook Pages : 203 - 206

CGP Revision Guide Pages : 93 - 95

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Show Specification Ref : 4.1.3c, 4.1.3d

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Question 1 / 5

AQA Jun 2011 Paper 2 Q6 do not write outside the box the table below shows the structures of three isomers with the molecular formula c h o e pent en ol pentanal isomer h c c c ch oh ch isomer ch ch ch ch isomer c o ch ch ch c o h c a complete the table by naming isomer mark b state the type of structural isomerism shown by these three isomers mark c the compound z pent en ol is a stereoisomer of e pent en ol c i draw the structure of z pent en ol mark wmp jun chem do not write outside the box c ii identify the feature of the double bond in e pent en ol and that in z pent en ol that causes these two compounds to be stereoisomers mark d 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 test reagent observation with isomer observation with isomer marks question continues on the next page turn over wmp jun chem e the following is the infrared spectrum of one of the isomers or do not write outside the box transmittance wavenumber cm e i deduce which of the isomers or would give this infrared spectrum you may find it helpful to refer to table on the data sheet mark e ii identify two features of the infrared spectrum that support your deduction in each case identify the functional group responsible feature and functional group feature and functional group marks wmp jun chem turn over for the next question do not write on this page answer in the spaces provided turn over wmp jun chem
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Question 2 / 5

AQA Jun 2012 Paper 2 Q7 do not write outside the box alkenes are useful intermediates in the synthesis of organic compounds a i complete the elimination mechanism by drawing appropriate curly arrows ho h h h ch c c c ch ch ch ch ch chch ch h o br h h br bromohexane hex ene a ii draw structures for the e and z stereoisomers of hex ene e isomer of hex ene z isomer of hex ene marks marks a iii state the meaning of the term stereoisomers marks extra space wmp jun chem do not write outside the box b the equation for the first reaction in the conversion of hex ene into hexan ol is shown below ch ch ch chch ch h so ch ch ch ch oso oh ch ch outline a mechanism for this reaction marks turn over for the next question turn over 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 2014 Paper 2 Q9 ethanol is an important fuel do not write outside the box a a dilute aqueous solution of ethanol can be produced by the fermentation of an aqueous solution of glucose it is claimed that the ethanol obtained from this solution is a carbon neutral biofuel write an equation for this fermentation reaction give two other essential conditions for this reaction to produce a good yield of ethanol name a process used to produce a much more concentrated solution of ethanol from a dilute aqueous solution state the meaning of the term carbon neutral in the context of this biofuel marks extra space question continues on the next page turn over wmp jun chem do not write outside the box b a student carried out a laboratory experiment to determine the enthalpy change when a sample of ethanol was burned the heat produced was used to warm some water in a copper calorimeter the student found that the temperature of g of water increased by c when mol of pure ethanol was burned in air use the student s results to calculate a value in kj mol for the enthalpy change when one mole of ethanol is burned the specific heat capacity of water is j k g deduce two reasons why the student s value for the standard enthalpy of combustion of ethanol is different from a data book value of kj mol marks extra space wmp jun chem do not write outside the box c mean bond enthalpies can be used to calculate enthalpies of reaction c i give the meaning of the term mean bond enthalpy marks c ii consider the mean bond enthalpy data in table table c h c c c o o o c o o h mean bond enthalpy kj mol to be calculated use the data in table and the equation shown to calculate a value for the bond enthalpy for the o o double bond in an oxygen molecule marks ch ch oh g o g co g h o g h kj mol end of questions wmp jun chem
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Question 5 / 5

AQA Jun 2016 Paper 2 Q8 section b answer all questions in the spaces provided do not write outside the box two reactions of bromopentane ch ch ch chbrch are shown c h reaction ch ch ch chbrch reaction c h oh the c h formed in reaction exists as a mixture of three isomers one of which is pent ene two of the isomers are a pair of stereoisomers all three isomers decolourise bromine a the same reagent is used in both reactions the product is determined by the choice of conditions state the reagent and the conditions for each of reaction and reaction state the role of the reagent in each reaction name and outline the mechanism of reaction for the formation of pent ene marks wmp jun chem do not write outside the box b all three isomers of c h contain the same functional group draw the displayed formula of pent ene draw the structures of the pair of stereoisomers and give their full iupac names explain the origin of the stereoisomerism shown marks turn over wmp jun chem do not write outside the box c the rates of hydrolysis of two chloroalkanes can be investigated by adding aqueous silver nitrate to the chloroalkanes during the hydrolysis reactions chloride ions are liberated slowly precipitates of silver chloride are formed outline a method to compare the rate of hydrolysis of chlorobutane with that of chlorobutane state how the method would ensure a fair test marks wmp jun chem turn over for the next question do not write on this page answer in the spaces provided turn over wmp jun chem
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