1 / 24

Organic Reactions

Organic Reactions. Point #1 3 basic kinds of reactions. A) Addition Reactions (like synthesis reactions) Hydrogenation saturating an unsaturated carbon chain alkene/yne to alkane Hydration alkene to alcohol Halogenation/Hydrohalogenation alkane to haloalkane alkene to haloalkane.

adamsr
Download Presentation

Organic Reactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Organic Reactions

  2. Point #13 basic kinds of reactions A) Addition Reactions (like synthesis reactions) • Hydrogenation • saturating an unsaturated carbon chain • alkene/yne to alkane • Hydration • alkene to alcohol • Halogenation/Hydrohalogenation • alkane to haloalkane • alkene to haloalkane

  3. B) Elimination Reactions (like synthesis reactions because they result in larger compounds) • Condensation • Esterification • Formation of alkene • Formation of amide (peptide bond)

  4. C) Substitution Reactions (like single or double replacement reactions where one atom/ion/functional group is replaced by another) • SN1 • SN2

  5. Point #2 Basic process of organic reactions is through attraction of positively (electrophile) and negatively (nucleophile) charged parts of molecules

  6. many organic reactions happen through the attraction of electrophiles for nucleophiles • in reaction mechanisms, curly arrows show how electrons move – generally electrons from nucleophile move to electrophile

  7. Point #3 Alkanes/Alkenes are relatively inert compared to other functional groups A) Alkenes have pi bonds in which electrons are easily accessible b/c they aren’t trapped between two nuclei as sigma bonding electrons are.

  8. B) Other functional groups have highly electronegative atoms like O, N or halogens

  9. The table below gives the characteristic reactions for several functional groups

  10. Reactions Example #1-Halogenation of alkane • Alkane + halogen gas  haloalkane • Need ultraviolet light for rxn to occur • Depending on time and amount of reactants, more than one halogen can added to the alkane

  11. -Reaction occurs through homolytic fission to form a free radical Formation of free radicals often results in chain reactions – reaction keeps occurring until all reactant is used up. See polymerization notes form mechanism. • Free radical is a element or molecule with an unpaired electron • Homolytic fission vs Heterolytic fission: • Fission means splitting apart • Heterolytic means that one atom takes both electrons in the bond and two ions are formed. • Homolytic means the bond is split in half – each side takes 1 electron and 2 free radicals are formed

  12. Example #2-Hydrohalogenation Hydrohalogenation of ethene • Alkene + acid halide  monohaloalkane • Halide ion adds to larger side (more substituted side of alkene) if there is one Hydrohalogenation of 1-propene

  13. Reaction occurs through heterolytic fission to form an ion • The first step is the attraction of the electrophile (Hydrogen ion) to the electrons in the pi bond. This forms a carbocation. • The carbocation that is more substituted (has more carbons attached to it) is the most stable. • The negatively charged halogen (nucleophile) adds to the carbocation to form the halogenated alkene.

  14. Example #3-Hydration Hydration of ethene • Alkene + water in acidic solution  alcohol • Acid acts as catalyst in rxn • –OH group adds to larger side (more substituted side) of alkene • Uses: hydration is used for commercial manufacture of ethanol Hydration of 1-propene

  15. Example #4 -Halogenation • Alkene + halogen gas  1,2-dihaloalkane • Diatomic gas has two atoms – both add to opposite sides of the double bond (and opposite sides of the molecule) • Uses: Chlorine + ethane  1,2-dichloroethane: used as starting material for PVC • Uses: Br2 dissolved in dichloromethane is used to distinguish between alkenes and alkanes. If reddish-brown color of Br2 disappears when added to unknown, the unknown has alkenes in it.

  16. Example #5 Hydrogenation • Alkene + Hydrogen gas (with catalyst) alkane • Hydrogenation is saturating an unsaturated hydrocarbon • Addition Reaction • Heterogeneous Catalyst: Pd or PtO2 (rxn occurs on a metal surface) • Uses: unsaturated vegetable oils are saturated to produce saturated fats (more solid at room temp than unsaturated) for margarines

  17. Example #6 Esterification • Carboxylic acid + alcohol  ester + water • Reaction conditions: acidic solution • The OH group on the carboxylic acid is replaced by the alcohols O-R group • Condensation reaction: produces water • Uses: flavouring agents, plasticizers, as solvents in perfume, polyesters

  18. Examples #7 Amide formation • Carboxylic acid + amine  amide + water • Reaction condition: difficult to conduct in simple steps • The OH group on the carboxylic acid is replaced by the amine (NH-R) • Condensation rxn: produces water • Uses: peptide bond formation, polymerization reactions to make nylons

  19. Example #8 Oxidation of alcohol • Alcohol + oxidizing agent  COOH (1, complete) /Aldehyde (1, partial)/Ketone (2) • Obviously an Oxidation reaction • Reaction condition: aqueous, acidic solution. The carboxylic acid and the aldehyde can be obtained through different experimental set-ups • Distill to get aldehyde • Heat under reflux to get COOH

  20. Oxidation of alcohol (continued) • Complete Oxidation: primary alcohol + oxidizing agent  carboxylic acid

  21. Oxidation of alcohol (continued) • Partial Oxidation: primary alcohol + oxidizing agent  aldehyde

  22. Oxidation of alcohol (continued) • Secondary alcohol + oxidizing agent  ketone

  23. Example #9 Condensation of alcohol • Condensation of alcohol alkene • Reaction conditions: • 170 and concentrated sulfuric acid or • H3PO4 and a catalyst or Al2O3 and a catalyst

More Related