Mechanisms of Benzene

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This is for the WJEC spec. CH4 exam. It is not a teaching source, its a revision guide. You need to know about it before watching. Thank you :)

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Slide 1:

Chemical Mechanisms Nitration of Benzene NO 2 O 2 N H NO 2 Conditions: Reflux below 55.C Reactants: Nitric+ Sulphuric Acid + H +

Slide 2:

Chemical Mechanisms Nitration of Benzene +HNO 3 NO 2 H 2 SO 4 H 2 SO 4 acts as a catalyst. At higher temperatures further substitution occurs Eletrophillic Substitution +H 2 O

Slide 3:

Chemical Mechanisms Chlorination of Benzene Cl δ + Cl Al Cl Cl Cl H Cl

Slide 4:

Chemical Mechanisms Chlorination of Benzene H Cl Al :Cl Cl Cl Cl - Cl +HCl +AlCl 3 Conditions: No light Room Temp No water present Reactants: Halogen Carrier ( AlCl 3) Eletrophillic Substitution

Slide 5:

Chemical Mechanisms Alkylation of Benzene C H H H I AlCl 3 CH 3 +HI Conditions: Room Temp No water present Reactants: Halogen Carrier(AlCl 3 ) + Eletrophillic Substitution

Slide 6:

Chemical Mechanisms Summary All Electrophillic Substitution A positively charged species, is substitutes a Hydrogen. A Halogen Carrier is needed Otherwise the Electrophile does not have a strong enough (+) charge

Slide 7:

Chemical Mechanisms Addition Reaction of Benzene + 2 NaOH O - Na + + NaCl H 2 O UNDER DRASTIC CONDITIONS 200 ATM 200.C Cl

Slide 8:

Chemical Mechanisms Addition Reaction of Benzene Very difficult for addition Addition across the double bonds in benzene, would cause the π electron to be destroyed. Even harder for halogenic Aromatic ring The P-orbitals of the Halogen, bind to the π electron cloud easily.

Slide 9:

Chemical Mechanisms Aromatic Side chain Halogenation CH 3 CH 2 Cl CHCl 2 Conditions: UV Light Reactants: Chlorine passed into boiling aromatic ring.