Eduqas Chemistry for A Level Year 2: Student Bk

Component 2 118 Content 119 The structure and bonding in benzene 120 The resistance of benzene to addition reactions 121 Electrophilic substitution in benzene compounds 124 The comparative strength of C–Cl bonds in chlorobenzene and chloroalkanes The first year of this course includes work on aliphatic and alicylic compounds. Aliphatic compounds are traditionally classed as compounds where the carbon atoms form open chains, rather than rings. Alicyclic compounds do have a ring structure but they react as if they are aliphatic compounds. In the second year of this course, aromatic compounds are introduced. The word ‘aromatic’ comes from the Latin word ‘aroma’ meaning fragrance. Not all aromatic compounds have a fragrant smell but they do all contain an aromatic ring system. The simplest aromatic compound is benzene, which has the formula C 6 H 6 . OA1.2 Aromaticity You should be able to demonstrate and apply knowledge and understanding of: The structure and bonding in benzene and other arenes. The resistance to addition reactions shown by aromatic compounds such as benzene. The mechanism of electrophilic substitution, such as in the nitration, halogenation and Friedel–Crafts alkylation of benzene, as the characteristic reactions of arenes. The interaction between benzene and substituent groups, as exemplified by the increase in C–Cl bond strength in chlorobenzene when compared to an alkene.