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Chapter 6: Organic Halogen Compounds; Substitution and Elimination Reactions.

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Presentation on theme: "Chapter 6: Organic Halogen Compounds; Substitution and Elimination Reactions."— Presentation transcript:

1 Chapter 6: Organic Halogen Compounds; Substitution and Elimination Reactions

2 Nucleophilic Substitution Examples of nucleophilic substitution reactions Nucleophile Substrate Leaving group

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5 Reaction of sodium ethoxide with bromoethane

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9 Nucleophilic Substitution Mechanism S N 2 Mechanism

10 S N 2 displacement reactions occure with inversion of configuration. For example, if we treat (R)-2-bromobutane with sodium hydroxide, we obtain (S)-2-butanol

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14 Example; Predict the product of the S N 2 reaction of cis-4-methylcyclohexyl bromide with cyanide ion

15 Arrange the following compounds in order of decreasing S N 2 reactivity toward sodium ethoxide

16 The S N 1 Mechanism

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19 Which of the following bromides will react faster with methanol (via S N 1 reaction)? and what are the reaction products in each case.

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21 S N 2 reactions in Nature: Biological Methylations

22 1. Negative ions are more nucleophilic, or better suppliers, than the corresponding neutral molecules. HO - > HOH RS - >RSH RO - > ROH 2. Elements low in the periodic table tend to be more nucleophilic than elements above them in the same column HS - > HO - I - > Br - > Cl - > F - 3. Across a row in the periodic table, more electronegative elements (the more tightly an element holds electron to itself) tend to be less nucleophilic.

23 Which mechanism, S N 1 or S N 2, would you predict for each of the following reactions?

24 Dehydrohalogenation, and Elimination Reaction; The E2 and E1 Mechanisms

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26 E1 mechanism

27 Substitution and Elimination in Competition Tertiary Halides

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29 Primary Halides

30 t-butoxide Ethoxide

31 Secondary Halides

32 Polyhalogenated Aliphatic Compounds

33 Chlorofluorocarbons (CFCs aka Freons)

34 Halons CBrClF 2 Bromochlorodifluoromethane (Halon-1211) CBrF 3 Bromotrifluoromethane Halon-1301


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