Docstoc

AROMATIC CHEMISTRY TEXTBOOK ANSWERS

Document Sample
AROMATIC CHEMISTRY TEXTBOOK ANSWERS Powered By Docstoc
					                             AROMATIC CHEMISTRY

                         Answers to end-of-chapter questions

1.   i)    In cylcohexene one double bond is hydrogenated
           In cyclohexa-1,3,5-triene three double bonds are hydrogenated            1
           So the enthalpy change should be 3 x –119.6 = -358.8 kJmol-1             1
     ii)   Benzene is more stable than cyclohexa-1,3,5-triene                       1
           Due to the delocalisation of the -electrons                             1
           So benzene is lower in energy (by 153 kJmol-1)                           1
           So there is less energy to release when it is hydrogenated               1
           (diagram gets third and fourth marks):

                                                                           Total 6 marks

2.   a)    step 1: acylation or electrophilic substitution                          1
           CH3CH2COCl and AlCl3                                                     2
           step 2: reduction                                                        1
           NaBH4                                                                    1
           step 3: elimination or dehydration                                       1
           conc H2SO4                                                               1
     b)                                                       +        -
            CH3CH2COCl + AlCl3                        CH3CH2CO + AlCl4
                                                                     -
                                                                  AlCl4
                    +                                        H
            CH3CH2CO
                                                        +
                                                             COCH2CH3


                                       COCH2CH3

                                               +     AlCl3
                                                                                    4

                                                                      Total 11 marks
3.   conc HNO3, conc H2SO4                                                   1
     HNO3 + H2SO4  HSO4- + NO2+ + H2O                                       1
     electrophilic substitution                                              1
                                   -
         HNO3 + H2SO4           HSO4 + NO+ + H2O
                                         2



                                                              -
                                                           HSO4
             +                                   H
           NO2
                                             +
                                                     NO2


                            NO2

                                        H2SO4
                                    +                                        4



                                                                    Total 7 marks

4.   a)   i)     CH3CH2Cl + AlCl3  CH3CH2 + AlCl4-                          1
          ii)    CH2=CH2 + HCl + AlCl3  CH3CH2+ + AlCl4-                    1
          iii)   electrophilic substitution                                  1
                                                                      -
                                                                   AlCl4
                        +                                      H
                   CH3CH2
                                                           +
                                                               CH2CH3


                                        CH2CH3

                                                 +    AlCl3
                                                                             4
     b)   ethene is a cheaper raw material                                   1
          the reaction is faster                                             1
     c)   phenylethene/styrene                                               1
          polyphenylethene/polystyrene                                       1

                                                                   Total 11 marks
5.   a)   step 1: acylation/electrophilic substitution                        1
          CH3COCl and AlCl3                                                   2
          step 2: nitration/electrophilic substitution                        1
          conc HNO3, conc H2SO4                                               1
          step 3: reduction                                                   1
          Sn and conc HCl                                                     1
     b)   HNO3 + H2SO4  HSO4- + NO2+ + H2O                                   1
                                                -
              HNO3 + H2SO4                HSO4 + NO+ + H2O
                                                       2



                                                                -
                                                             HSO4
                  +                                  H
                NO2
                                                +
                                                       NO2


                                 NO2

                                            H2SO4
                                        +                                     4

                                                                    Total 12 marks

6.   a)   C6H5CH2Br + 2NH3  C6H5CH2NH2 + NH4Br                               2
          nucleophilic substitution                                           1
     b)   reduction                                                           1
          C6H5CN + 4[H]  C6H5CH2NH2                                          1
          LiAlH4                                                              1

                                                                     Total 6 marks

                                                             TOTAL 53 MARKS

				
DOCUMENT INFO
Shared By:
Stats:
views:35
posted:7/17/2011
language:English
pages:3
About