Alkenes

• What type of hydrocarbons are alkenes?

  Unsaturated hydrocarbons
• What is the general formula for alkenes?

  $C_nH_{2n}$
• What does the general formula for alkenes apply to?

  Compounds with one double bond
• What type of reactions do alkenes undergo?

  Addition reactions
• What is the structural formula for ethene?

  $CH_2=$$CH_2$
• What is the structural formula for buta-1,3-diene?

  $CH_2=$$CH-CH=$$CH_2$
• Why are alkenes reactive?

  They have high electron density from double bonds
• What are cycloalkenes?

  Cyclic alkenes with two fewer hydrogens
• What is the electrophile in addition reactions of alkenes?

  An electron pair acceptor
• What does a curly arrow represent in reaction mechanisms?

  Movement of electrons
• What happens when bromine water is added to an alkene?

  It decolorizes from brown to colorless
• What is formed when bromine adds to an alkene?

  Di-bromoalkane
• What is a carbocation?

  A positively charged carbon intermediate
• What stabilizes a carbocation?

  Alkyl groups donating electrons
• What type of carbocation is more stable?

  Tertiary carbocation
• What is the role of sulfuric acid in alkene reactions?

  It acts as a catalyst
• What is formed when alkenes react with sulfuric acid?

  Alkyl hydrogen sulfates
• What is the formula for sulfuric acid?

  H₂SO₄
• What are the key characteristics of alkenes?

  • Unsaturated hydrocarbons
  • Contain double bonds
  • General formula: $C_nH_{2n}$
  • Undergo addition reactions
• What are the steps in the electrophilic addition mechanism for alkenes?

  1. Electrophile approaches double bond
  2. Curly arrow shows electron movement
  3. Carbocation intermediate forms
  4. Nucleophile attacks carbocation
  5. Product is formed
• What factors affect the stability of carbocations?

  • Number of alkyl groups attached
  • Tertiary > Secondary > Primary stability
  • Alkyl groups donate electrons to stabilize
• What are the products of alkene reactions with hydrogen halides?

  • Halogenoalkanes
  • Depends on carbocation stability
  • Major and minor products possible
• What is the significance of the addition of bromine to alkenes?

  • Test for alkenes
  • Color change indicates reaction
  • Forms di-bromoalkanes
• What is the product formed when alkenes react with cold concentrated sulfuric acid?

  Alkyl hydrogen sulfates
• What role does sulfuric acid play in the reaction with alkenes?

  It acts as a catalyst
• What is produced when alkyl hydrogen sulfate is hydrolyzed?

  Ethanol
• How does sulfuric acid interact with alkenes in the reaction mechanism?

  It forms a carbocation intermediate
• What is the chemical formula for sulfuric acid?

  H₂SO₄
• What does hydrolysis mean in the context of this reaction?

  Breaking a bond using water
• What are the steps in the reaction from alkenes to alcohols using sulfuric acid?

  1. Alkene reacts with sulfuric acid.
  2. Forms alkyl hydrogen sulfate.
  3. Alkyl hydrogen sulfate is hydrolyzed with cold water.
  4. Produces ethanol and regenerates sulfuric acid.
• What type of alkenes can produce two products during the reaction?

  Asymmetric alkenes
• What are the types of polymers made from alkenes?

  • Natural polymers (e.g., proteins, rubber)
  • Synthetic polymers (e.g., polyethylene, polypropylene)
• Who discovered vulcanized rubber?

  Charles Goodyear
• What is the process of addition polymerization?

  Joining monomers to form polymers
• What is the monomer used to make polypropylene?

  Propene
• How do longer polymer chains affect melting points?

  They increase melting points
• What are the intermolecular forces in most polyalkenes?

  Van der Waals forces
• What effect does branching have on polymer chains?

  It makes them more flexible
• What is PVC commonly used for?

  Drain pipes and guttering
• What do plasticizers do to polymers?

  Make them more flexible