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Common Organic Reactions. Chapter 1. Four Types. A ddition Reactions E limination Reactions S ubstitution Reactions O xidation AESO ………………………. A. Addition Reaction. Atoms are added to a double or triple bond What type of organic compounds will undergo this type of reaction?
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Common Organic Reactions Chapter 1
Four Types • Addition Reactions • Elimination Reactions • Substitution Reactions • Oxidation • AESO………………………
A. Addition Reaction • Atoms are added to a double or triple bond • What type of organic compounds will undergo this type of reaction? • Alkenes and alkynes • Aldehydes and ketones
Alkenes and Alkynes • Reaction with H2 : Hydrogenation(needs heat, pressure and platinum, Pt, catalyst) • Reaction with Halogen, X2 : Halogenation • Reaction with Hydrogen halide, HX ; Hydro-halogenation • Reaction with Water, HOH : Hydration produces R-OH alcohol (sulphuric acid, H2SO4, catalyst)
Alkenes and Alkynes • Hydrogenation: Ethane
Practice this Now!! 1. Draw structural diagrams to illustrate the following reactions. • reaction of propene with hydrogen gas, H2 • reaction of 3, 4-dimethyl-3-hexene with hydrogen gas, H2 (note: Alkynes need more H2)
Alkenes and Alkynes • Halogenation – addition of X2
Practice this Now!! • Draw structural diagrams to illustrate the following reactions: • reaction of 1-butyne with chlorine gas, Cl2 b) reaction of 2-methyl-1-butene and bromine, Br2
Alkenes and Alkynes • Hydrohalogenation – addition of HX (HCl, HBr, HF, HI) The Halogen is added to the C- atom containing the least number of H-atoms – MARKOWNIKOFF’s RULE
Practice this Now!! 1. Draw structural diagrams to illustrate the following reactions. a) reaction of 2-methyl pentene and HCl b) reaction of 1-propyne with HBr
Alkenes • Hydration: Addition of HOH Alkenes follows MARKOWNIKOFF’s RULE – OH group is added to the C-atom with the least number of H-atoms forming alcohols.
Alkynes • Hydration: Addition of HOH Alkynes do not form alcohols – instead they form aldehydes (-CHO) and ketones
Practice this Now!! 1. Draw structural diagrams to illustrate the following reactions. a) reaction of 1-butene with water b) reaction of 3-methylbutyne with water
Aldehydes and Ketones • Addition of H2 : Hydrogenation or Reductionproducing R-OH alcohol (heat, pressure and platinum (Pt) as catalyst are required).
Practice it Now!! 1. Draw structural diagrams to illustrate the following reactions. a) reaction of propanal with hydrogen b) reaction of 2-propanone with hydrogen
Elimination Reactions • The removal of an atom(s) or small molecule from an organic molecule, resulting in the formation of a double or triple bond. | | | | — C—C — → — C = C — + XY | | X Y Shown by alkyl halides and alcohols
Alkyl Halides Dehydrohalogenation: • elimination of HX molecule from alkyl halide (requires alcoholic KOH) • Forms alkenes
Practice it Now!! Write down the products formed from a reaction of : a) 2-chlorobutane and alcoholic KOH b) 2-chloro-2-methylpentane and alcoholic KOH
Alcohols Dehydration: • Removal of HOH • Formsalkene • sulphuric acid, H2SO4 is required as a catalyst
Practice it Now!! What products will form if: • cyclohexanol undergoes dehydration in presence of suphuric acid • 2-methyl-2-propanol undergoes dehydration in prescence of sulphuric acid.