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Alkene/Alkyne Addition Reactions

Alkene/Alkyne Addition Reactions. The double and triple bonds present in alkenes and alkynes, respectively, make them much more reactive than alkanes. Alkenes and alkynes undergo addition reactions

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Alkene/Alkyne Addition Reactions

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  1. Alkene/Alkyne Addition Reactions • The double and triple bonds present in alkenes and alkynes, respectively, make them much more reactive than alkanes. • Alkenes and alkynes undergoaddition reactions • a reaction in which parts of a reactant are added to the two atoms that make up a double or triple bond

  2. Alkene/Alkyne Addition Reactions • Two simple addition reactions: H H H H C = C + Br2 H - C - C - H H H Br Br Cl Cl H - C C - H + 2 Cl2 H - C - C - H Cl Cl

  3. Alkene/Alkyne Addition Reactions • Some of the common reactants that can add to alkenes and alkynes include: • Br2 • I2 • Cl2 • H2 (requires a transition metal catalyst) • H2O (requires a strong acid catalyst) • HBr • HCl • HI

  4. Alkene/Alkyne Addition Reactions Example: Write the structure of the product that forms when 1-butene reacts with the following reagents (individually): Br2 H2 + Ni catalyst HBr

  5. Alkene/Alkyne Addition Reactions • Markovnikov’s Rule:The major product obtained from the addition of an unsymmetrical reagent such as H-Br, H-Cl, or H-OH to an alkene or alkyne is the one obtained when the H atom of the reagent is added to the C atom of the multiple bond that already has the greater number of H atoms. “The rich get richer”

  6. Alkene/Alkyne Addition Reactions Example: Write the structure of the product that forms when 1-propyne reacts with the following reagents (individually): Br2 (excess) H2 (excess) with Ni catalyst HBr (excess)

  7. Hydroxyl groups Alcohols • Alcohols: • hydrocarbon derivatives in which one or more of the H atoms has been replaced by a hydroxyl group (alcohol functional group) C - O - H OR C - OH

  8. Alcohols • Alcohols are named in the exact same manner as alkanes, alkenes, and alkynes except: • To find the base name, drop the “e” from the name of the corresponding alkane and add “ol” • Use the carbon number to identify the position of the alcohol. CH3CH2CHCH3 OH CH3CH2CH2OH 1-propanol 2-butanol

  9. Alcohols Examples: Draw the structures for the following alcohols. Methanol Ethanol 2-Propanol 2-methyl-2-propanol

  10. Alcohols • The position of the alcohol in the chain has a significant impact on the reactivity of the alcohol. • A primary alcohol (1o) is an alcohol in which the OH group is attached to a carbon which is bonded to only 1 other C atom. • CH3CH2OH

  11. Alcohols • A secondary alcohol (2o) is an alcohol in which the OH group is attached to a carbon which is bonded to two other carbon atoms. • CH3CHCH3 OH • CH3CH2CHCH2CH3 OH

  12. Alcohols • A tertiary alcohol (3o) is an alcohol in which the OH group is attached to a C which is bonded to three other carbon atoms. CH3 CH2CH3 CH3CCH3 CH3CH2CCH3 OH OH

  13. Alcohols Example: Identify the following alcohols as 1o, 2o, or 3o. Name each alcohol. CH3 CH3 CH3CHCH2OHCH3CH2CCH3 OH CH3CHCH2OH OH

  14. Carboxyl group Reactions of Carboxylic Acids • Carboxylic acids contain a carboxyl group: O CH3C-O-H OR CH3CO2H

  15. Reactions of Carboxylic Acids • Carboxylic acids can participate in a variety of reactions: • acid-base reactions • similar to those of inorganic (without C-C bonds) acids • condensation reactions • esterification • amidation

  16. Reactions of Carboxylic Acids • Esterification: • a condensation reaction in which a carboxylic acid reacts with an alcohol to form an ester and water. O O CH3C - OH + HO-CH2CH3 CH3C-O-CH2CH3+ H2O

  17. Reactions of Carboxylic Acids Example:Predict the products formed during the following reactions. O CH3C - OH + CH3 CH2CH2OH O C - OH + CH3OH

  18. Reactions of Carboxylic Acids • Amidation: • a condensation reaction in which a carboxylic acid reacts with an amine that contains a hydrogen bonded to nitrogen to form an amide and water O O CH3C - OH + H2N-CH2CH3 CH3C-NH-CH2CH3+ H2O

  19. Reactions of Carboxylic Acids Example:Predict the products formed during the following reactions. O CH3 CH2C - OH + CH3CH2NH2 O C - OH + CH3NH2

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