AS Organic Chemistry - A-level chemistry _AQA_

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AS Organic Chemistry - A-level chemistry _AQA_ Powered By Docstoc
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Date Due : ……………………………………………………………




              Year 13                80%     A
                                     70%     B
           A2 Chemistry              60%     C
            2007-2008                50%     D
                                     40%     E
                                     Below   U

  Organic Questions Part I



        Questions on                         %
     AS Organic Chemistry,
      Optical Isomerism &
     Carbonyl Compounds
                                             65
13.4 Isomerism Assessed Homework Part I


                                                 SECTION A

Use the following grid to help you answer questions 1 – 10:


             Summarised directions for recording responses to multiple completion
                                          questions

                    A                   B                     C                 D
           (i), (ii) and (iii)   (i) and (iii) only   (ii) and (iv) only   (iv) alone
                   only

1.   Correct statements about non-cyclic compounds include

     1         there are two geometrical isomers of C3H5Cl

     2         there are two position isomers of C3H7Cl

     3         there are two optical isomers of C3H6Cl2

     4         there are two chain isomers of C3H8



2.   Possible products formed on reduction of CH3CH=CHCHO include

     (i)       CH3CH=CHCH2OH

     (ii)      CH3CH=CHCOOH

     (iii)     CH3CH2CH2CH2OH

     (iv)      CH3CH2CH2COOH

                                                                                 Answer:



3.   Which of the following statements about the ant pheromone hex-2-enal,
     CH3CH2CH2CH=CHCHO, is/are true?

     (1)       It undergoes electrophilic addition reactions.

     (2)       It can be oxidised to a carboxylic acid.

     (3)       It undergoes nucleophilic addition reactions.

     (4)       It does not exist in stereoisomeric forms.

                                                                                 Answer:




                                                                                           1
13.4 Isomerism Assessed Homework Part I


4.   Initial nucleophilic attack on the organic compound occurs in

                        Cl
     (1)                 
             CH3CH2CH3 2  CH3CHClCH3

     (2)                HBr
             CH3CH=CH2  CH3CHBrCH3

                          H 2SO 4
     (3)     CH3CH2CH2OH   CH3CH=CH2

                        HCN
     (4)                  
             CH3CH2CHO    CH3CH2CH(OH)CN

                                                                           Answer:



5.   Which of the following pairs of compounds react to produce a deposit of metallic silver?

     (i)     Aqueous sodium chloride and aqueous silver nitrate,

     (ii)    Copper and aqueous silver nitrate,

     (iii)   Propanone and ammoniacal silver nitrate,

     (iv)    Propanal and ammoniacal silver nitrate.

                                                                           Answer:



6.   Free radical reactions include

     (i)     CH3CH2CH2CH2CH3  CH3CH=CH2 + CH3CH3

     (ii)    CH3CH2CHO + HCN  CH3CH2CH(OH)CN

     (iii)   CH3CH3 + Cl2  CH3CH2Cl + HCl

     (iv)    CH3CH = CHCH3 + Br2  CH3CHBrCHBrCH3

                                                                           Answer:

7.   Compounds which have stereoisomers include

     1       ClCH2CH(CH3)CH2CH2Cl

     2       (CH3)2C=CHCH2Cl

     3       CH3CHClCH2CH2CH2Cl

     4       (CH3) 2CHCH=CCl2


                                                                           Answer:


                                                                                                2
13.4 Isomerism Assessed Homework Part I



8.    Correct statements about CH3CH2CH=CHCOOH include

      (1)    it can be formed by oxidation of pent-3-en-1-ol.

      (2)    it forms an addition polymer.

      (3)    it exists as two optical isomers.

      (4)    it is a structural isomer of                      O

                                                           O

                                                                                                 Answer:


9.    A mechanism for the reaction between ammonia and ethanoyl chloride is given below.
                                                  –
                      O                               O:                           O                  O
                                   Step 1                          Step 2              Step 3
            H3C       C       Cl            H3C       C    Cl               H3C    C            H3C   C    NH 2

                      N                            N+                              N+
                  H       H                       H H                             H H
                      H                            H                               H

      Correct statements include

      1      the ammonia behaves as a nucleophile.

      2      the proton loss in step 3 has been shown incorrectly.

      3      the ammonia attacks an electron-deficient carbon atom.

      4      this mechanism is called nucleophilic substitution.

                                                                                                 Answer:


10.   Pairs of functional group isomers include

      1      CH3CH2CH2CH2NO2 and CH3CH2CH(NH2)COOH

      2      HOCH2CH2CH2CHO and CH3COCH2CH2OH

      3      H2NCH2CH2CH2COOH and H2NCH2COOCH2CH3

      4      CH3CH2CH=CH2 and CH3CH=CHCH3



                                                                                                 Answer:




                                                                                                                  3
13.4 Isomerism Assessed Homework Part I


11.   This question concerns the preparation of the plastic poly(methyl 2-methylpropenoate)
      (Perspex), starting from propanone.

                                                   CN                            CN
                                 Step 1                          Step 2
                   CH 3 COCH 3            H 3C     C     CH3              H 2C   C     CH 3

                                                   OH                       Compound L

                                            Compound K                               Step 3


                    H   COOCH3                     COOCH 3                       COOH
                             Step 5                              Step 4
                   C    C n               H 2C     C     CH 3             H 2C   C     CH 3

                    H   CH3                 Compound N                     Compound M


      Which one of the following sets of reagents is not suitable for the step indicated?

      A     Step 1 HCN (NaCN then dilute HCl)

      B     Step 2 hot ethanolic KOH

      C     Step 3 warm aqueous H2SO4

      D     Step 4 CH3OH with an acid catalyst

                                                                                 Answer:
12.   Ibuprofen is a drug used as an alternative to aspirin for the relief of pain, fever and
      inflammation.
      The structure of ibuprofen is shown below.

                                                          O
                                                 H 3C     C
                                                        CH OH




                                                        CH 2
                                                        CH
                                                 H 3C     CH 3

      Which one of the following statements is not correct?

      A     It has optical isomers.

      B     It liberates carbon dioxide with sodium carbonate solution.

      C     It undergoes esterification with ethanol.

      D     It undergoes oxidation with acidified potassium dichromate(VI).

                                                                                      Answer:



                                                                                                4
13.4 Isomerism Assessed Homework Part I

13.   This question concerns the preparation of the plastic poly(methyl 2-methylpropenoate)
      (Perspex), starting from propanone.

                                                      CN                          CN
                                      Step 1                      Step 2
                  CH 3 COCH 3                  H 3C   C    CH3             H 2C   C     CH 3

                                                      OH                     Compound L

                                                 Compound K                           Step 3


                   H       COOCH3                     COOCH 3                     COOH
                                Step 5                            Step 4
                   C       C n                 H 2C   C    CH 3            H 2C   C     CH 3

                   H       CH3                   Compound N                 Compound M


      Which one of the following is not a structural isomer of Compound M?

      A                O          O
            H 2C            C

             H 2C          CH 2

      B
                            H
            H2C        C
                            COOCH3

      C
                   O
            H 2C       CH       CH 2OH

      D
                         O
            H 3C       CH CH           CHO

                                                                                      Answer:




                                                                                                5
13.4 Isomerism Assessed Homework Part I

Section B
14.   Consider the reaction scheme below which starts from butanone.

                                                                                         CN
                                                         Reaction 1
                    H3 C        C       CH 2 CH 3                            H 3C        C       CH 2 CH 3

                                O                                                        OH
                                                                                         A
                                     Reaction 2


                                 H                        excess
                                                        conc, H 2 SO 4
                    H 3C        C       CH 2 CH 3                                  but–1–ene and but–2–ene
                                                             180°C
                                OH
                                B

      (a)   (i)     Give a suitable reagent for Reaction 1 and state the type of mechanism
                         involved.

                    Reagent. ........................................................................................................

                    Type of mechanism. .......................................................................................

            (ii)    Outline the mechanism for reaction 1.




            (iii)   When 5.0 g of butanone were used to carry out Reaction 1, the yield was
                    64% of the theoretical maximum. Calculate the mass of compound A
                    formed.

                    ........................................................................................................... .............

                    ........................................................................................................................

                    ........................................................................................................................
                                                                                                                                                (10)

      (b)   (i)     Give a suitable reagent for Reaction 2.

                    ........................................................................................................................

            (ii)    Product B is found to be optically inactive. Suggest why this is so.

                    .......................................................................................................................

                    ........................................................................................................................

                                                                                                                                                  6
13.4 Isomerism Assessed Homework Part I



      (c)   Draw the structure of the repeating unit in the polymer which can be formed from
            but-1-ene.




                                                                                                                                  (4)
                                                                                                                     (Total 14 marks)


15.   Consider the following reaction scheme.

                                                                              Reaction 2                              O
                                                  CH 3 CH 2 CH 2 OH                                CH 3 CH 2 C
                           Reaction 1                         Q                                            R          OH

                                O
             CH 3 CH 2 C
                                H                                   OH
                   P
                           Reaction 3
                                                   CH 3 CH 2        C     H

                                                                    CN

      (a)   Give the reagent(s) for Reaction 1, name the type of reaction involved and give
            the mechanism for the reaction.

            Reagent(s)................................................................................................................

            Type of reaction........................................................................................................

            Mechanism




                                                                                                                                         (6)

      (b)   (i)     Give the reagent(s) and conditions for Reaction 2.

                    Reagent(s)......................................................................................................

                    Conditions.......................................................................................................

            (ii)    Write an equation for this reaction using the symbol [O] to represent the
                    oxidising agent.


                                                                                                                                         (4)


                                                                                                                                          7
13.4 Isomerism Assessed Homework Part I



      (c)    Reaction 3 produces a mixture of two stereoisomers.

             (i)           What is the relationship between these two isomers?

                           ........................................................................................................................

                           ........................................................................................................................

             (ii)          How can separate samples of these isomers be distinguished?

                           ........................................................................................................................

                           ........................................................................................................................
                                                                                                                                                      (3)


      (d)    Write an equation for the complete combustion of P.

             ............................................................................................................................. ....
                                                                                                                                              (2)
                                                                                                                                 (Total 15 marks)




16.    (a)          Give the structural formulae, showing all the covalent bonds for all the isomers
                    of C4H9Br and name them.




                                                                                                                                                      (3)
       (b)          The compounds in (a) all react on heating with aqueous sodium hydroxide by a
                    nucleophilic substitution reaction. For one of these isomers, the reaction at a given
                    temperature was found to be first order with respect to the organic molecule and
                    first order overall.
                    (i)           Explain what is meant by the term nucleophile
                                  ………………………………………………………………………………………
                                  ………………………………………………………………………………………
                    (ii)          Identify the nucleophile in this reaction
                                  ……………………………………………………………………………
                    (iii)         Write a rate expression for this reaction
                                  …………………………………………………………………………….
                                                                                                                                                      (3)

                                                                                                                                                       8
13.4 Isomerism Assessed Homework Part I


(c)   (i)     Identify the isomer in (a) that is chiral and explain briefly why it is chiral.




                 …………………………………………………………………………….
                 …………………………………………………………………………….
                                                                                                      (2)
                                                                                            TOTAL 8 marks


17.     This question concerns the compound Q pent-3-en-ol
                 CH3CH(OH)CH=CHCH3


        (a)      Give the structural formula of a compound isomeric with Q which does not contain a
                 carbon-carbon double bond.




                                                                                                      (1)


        (b)      Q shows two types of isomerism
                 (i)     Draw the geometric isomers of Q and state why Q shows this type of
                         isomerism




                         ………………………………………………………………………………………
                         ………………………………………………………………………………………
                                                                                                      (2)




                                                                                                       9
13.4 Isomerism Assessed Homework Part I


                   (ii)          Draw the optical isomers of Q and state what effect such isomers have on
                                 the plane of plane polarised light




                                 ………………………………………………………………………………………
                                 ………………………………………………………………………………………
                                                                                                                                                     (3)
                                                                                                                              (TOTAL 6 marks)


18.   (a)   Consider the following pair of isomers.

                                           O                                                          O
                               H      C                                                 HO        C
                                           OCH 2 CH 2 CH 3                                            CH 2 CH 2 CH 3

                                                C                                                     D

            (i)           Name compound C.

                          ........................................................................................................................

            (ii)          Identify a reagent which could be used in a test-tube reaction to distinguish
                          between C and D. In each case, state what you would observe.

                          Reagent .........................................................................................................

                          Observation with C .........................................................................................

                          Observation with D..........................................................................................
                                                                                                                                                     (4)

      (b)   Consider the following pair of isomers.

                                          O                                                         O
                           H3 C       C                                                 H      C
                                          CH 2 CH 2 CH 3                                            CH 2 CH 2 CH 2 CH 3

                                           E                                                          F

            (i)           Name compound E.

                          ........................................................................................................................



                                                                                                                                                     10
13.4 Isomerism Assessed Homework Part I



          (ii)   Identify a reagent which could be used in a test-tube reaction to distinguish
                 between E and F. In each case, state what you would observe.

                 Reagent .........................................................................................................

                 Observation with E ........................................................................................

                 Observation with F..........................................................................................
                                                                                                                                     (4)

    (c)   Draw the structure of the chain isomer of F which shows optical isomerism.




                                                                                                                               (1)
                                                                                                                   (Total 9 marks)




                                                                                                                                     11

				
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