1 / 48

Organic Reactions

Organic Reactions. SCH4U – Unit B. Types of organic reactions. Addition Elimination Substitution Condensation (dehydration synthesis) Esterfication Hydrolysis Oxidation Reduction Combustion Complete Incomplete. Addition.

edena
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 SCH4U – Unit B

  2. Types of organic reactions • Addition • Elimination • Substitution • Condensation (dehydration synthesis) • Esterfication • Hydrolysis • Oxidation • Reduction • Combustion • Complete • Incomplete

  3. Addition • Reaction in which atoms are added to a carbon-carbon double or triple bond • LOOK FOR: check if C atoms in product(s) are bonded to more atoms than C atoms in reactant • Alkenes and alkynes generally react with one of four reactants: • H2, H-H  example #1 • H2O, H-OH  example #2 • Acid Halides, H-X (X = F, Cl, Br, I)  example #3 • Diatomic Halogens, X-X  example #4

  4. Addition • Example #1 2-butene butane

  5. Addition • Example #2 2-butanol 2-butene

  6. Addition • Example #3 2-fluoro butane

  7. Addition • Example #4 2,3-difluoro butane

  8. Addition • When adding halogens to an alkyne, a total of four atoms can be added • The amounts of the halogen reactant must be considered: • Excess  example #5 • Limited  example #6

  9. Addition • Example #5 (excess halogen) 2,2,3,3-tetrafluoro butane

  10. Addition • Example #6 (limited halogen) 2,3-difluoro 2-butene

  11. Addition • If the alkene/alkyne contains many C atoms and is reacting with a small molecule, isomers may form  example #7 • If the small molecule reacts with an asymmetrical alkene, can use Markinnikov’srule to predict the more abundant isomer  example #8 • Markovnikov’srule: H atom of a small molecule will attach to C atom of double bond that is already bonded to the most H atoms

  12. Addition • Example #7 • 50% 2-bromo pentane • 50% 3-bromo pentane

  13. Addition • Example #8 2-bromo pentane

  14. Elimination • Reaction in which atoms are removed from an organic molecule to form a double bond • LOOK FOR: check if C atoms in product(s) are bonded to less atoms than C atoms in reactant • Basically, this is the reverse of an addition reaction • Methods of undergoing elimination reactions: • Heat and strong acid (catalyst)  used for alcohols  example #1 • Heat and strong base (catalyst)  used for haloalkanes example #2

  15. Elimination • Example #1

  16. Elimination • Example #2

  17. Elimination • If an asymmetrical molecule undergoes an elimination reaction, constitutional isomers can form  example #3 • General rule: H atom most likely to be removed from C atom with most C-C bonds • “The poor get poorer!” • opposite of Markovnikov’s Rule • Called Zaitsev’s rule

  18. Elimination • Example #3 (major product) (minor product)

  19. Substitution • Reaction in which a hydrogen atom or functional group is replaced by a different atom or functional group • LOOK FOR: • Two compounds react to form two different compounds • Carbon atoms are bonded to the same number of atoms in product and reactant

  20. Substitution • Alcohols and haloalkanes undergo substitution reactions relatively easily • Alcohol reacts with acids containing a halogen (HCl, HBr, etc.) to produce a haloalkane example #1 • Haloalkane reacts with hydroxide to produce an alcohol  example #2 • Haloalkanes also react with bases to undergo elimination reactions • Thus, hard to control reactions of haloalkanes with bases • For the purposes of our course: • OH– = substitution reaction • NaOCH2CH3 = elimination reaction

  21. Substitution • Example #1 ethanolchloroethane

  22. Substitution • Example #2 chloroethane ethanol

  23. Substitution • Alkanes also undergo substitution reactions • Alkanes are relatively unreactive, thus a lot of energy is required (UV light) to catalyze rxn • Alkanes react with chlorine and bromine to form haloalkanes • If enough of the halogen is present, a mix of organic compounds forms  example #3 • Ultimately, because of the mix of products, this process is not used to produce haloalkanes

  24. Substitution • Example #3

  25. Substitution • Aromatic hydrocarbons (benzene derivatives) are also stable • Require a catalyst to react with chlorine and bromine  example #4

  26. Substitution • Example #4 benzene bromobenzene

  27. Condensation • Reaction in which two molecules combine to form a larger molecule, producing a small, stable molecule, usually water, as a second product or functional group • LOOK FOR: Hydroxyl group from one molecule and a hydrogen atom from a second molecule being removed, and water being produced • EXTREMELY IMPORTANT IN BIOLOGY! • Generally forms an amide bond when it occurs between ~COOH and ~NH2

  28. Condensation • Example #1 carboxylic amine amide water acid

  29. Condensation • Example #2

  30. Esterification (condensation) • Reaction of a carboxylic acid with an alcohol to form an ester and water • Specific type of condensation reaction  example #3 • Catalyzed by a strong acid  H2SO4 • Flavours and smells of fruits and spices are due to ester compounds • Can be duplicated in a lab • Production of synthesized ester compounds used to flavour juices, candies, etc.  example #4 (cherry flavour)

  31. Esterification (condensation) • Example #3 carboxylic alcohol ester water acid

  32. Esterification (condensation) • Example #4 benzoic ethanol ethyl water acid benzoate

  33. Hydrolysis • Reaction in which a molecule is broken apart by adding hydroxyl group from a water molecule to one side of a bond and hydrogen atom of same water molecule to other side of bond • Basically, this is the reverse of a condensation reaction • LOOK FOR: a large molecule containing an ester or amide reacting with water to produce to smaller molecules  example #1

  34. Hydrolysis • Example #1 ester water carboxylic alcohol acid

  35. Hydrolysis • Both the condensation reaction and hydrolysis reaction are catalyzed by acid  example #2 • The double arrow indicates the reaction is reversible • How can we control the direction of a reversible reaction to favour one side of the equation??? • EQUILIBRIUM! (Unit #4)

  36. Hydrolysis • Example #2 carboxylic alcohol ester water acid

  37. Oxidation • Reaction in which a carbon atom forms more bonds to oxygen atoms or fewer bonds to hydrogen atoms (orgo) • Always occurs along with a reduction reaction • For organic chemistry, focus only on the organic compound • Some oxidation reactions can also be classified as elimination reactions

  38. Oxidation • Occurs when organic compound reacts with an oxidizing agent • KMnO4 = potassium permanganate • K2Cr2O7 = acidified potassium dichromate • O3 = ozone • Redox reactions are often left unbalanced  examples #1-3

  39. Oxidation • Example #1 • C atom has lost H atoms

  40. Oxidation • Example #2 • C atom has gained an O atom

  41. Oxidation • Example #3 ethanol ethanal

  42. Reduction • Reaction in which a carbon atom forms fewer bonds to oxygen atoms or more bonds to hydrogen atoms (orgo) • Always occurs along with an oxidation reaction • For organic chemistry, focus only on the organic compound • Some reduction reactions can also be classified as addition reactions

  43. Reduction • Occurs when organic compound reacts with an reducing agent • LiAlH4 = lithium aluminum hydride • H2/Pt = hydrogen gas over a platinum catalyst • Redox reactions are often left unbalanced  examples #1-3 • Redox reactions will be covered in greater depth during ELECTROCHEMISTRY (Unit #5)!

  44. Reduction • Example #1 aldehyde or ketone alcohol • C atom has less bonds to O atom

  45. Reduction • Example #2 alkenealkane • C atoms have more bonds to H atoms

  46. Reduction • Example #3 propanone 2-propanol • C atom has less bonds to O atom

  47. Combustion • Type of reaction in which a compound reacts with oxygen to produce the oxides of elements that make up the compound • 2 types: • Complete combustion: an excess of oxygen reacts with a hydrocarbon and produces carbon dioxide and water vapour, and releases energy • Incomplete combustion: reaction that occurs when insufficient oxygen is present; all elements in the fuel will not combine with oxygen to the greatest extent possible

  48. Combustion • Example #1 HC + O2(g)  CO2(g) + H2O(g) + energy • Example #2 HC + O2(g)  C(s) + CO(g) + CO2(g) + H2O(g) + energy

More Related