10. aromatics

• What is the formula for benzene?

  C$_6$H$_6$
• What type of compound is benzene?

  Cyclic compound
• How many valence electrons does each carbon in benzene have?

  Four valence electrons
• What is the bond length of carbon-carbon bonds in benzene?

  139 picometers
• What does the delocalized electron structure of benzene contribute to?

  Stability and equal bond lengths
• What is the skeletal formula used for?

  To draw benzene and its derivatives
• Who proposed the alternating double bond structure of benzene?

  Auguste Kekulé
• What does the circle in the benzene structure represent?

  Delocalized electron system
• Why is benzene more stable than cyclohexene?

  Due to its delocalized electron structure
• What is the enthalpy change of hydrogenation for cyclohexene?

  • 120 kilojoules per mole
• What is the predicted enthalpy change of hydrogenation for benzene if it had three double bonds?

  • 360 kilojoules per mole
• What is the actual enthalpy change of hydrogenation for benzene?

  • 208 kilojoules per mole
• What does a lower negative enthalpy change indicate about benzene's stability?

  More energy is required to break its bonds
• What are the key properties of benzene?

  • Cyclic and planar structure
  • Delocalized electrons
  • Equal bond lengths (139 picometers)
  • More stable than cyclohexene
• What are the next topics to be covered after benzene's structure?

  • Naming benzene derivatives
  • Reactions such as Friedel-Crafts and nitration
• What is the bond length in benzene?

  Equal in all bonds
• Why is benzene considered more stable?

  It requires more energy to break bonds
• What is the electron structure of benzene?

  Delocalized electron structure
• What are the derivatives of benzene called?

  Arenes
• What is an example of a halogen derivative of benzene?

  Bromobenzene
• How do we name derivatives of benzene?

  By adding the substituent before benzene
• What is the name for benzene with a methyl group?

  Dimethylbenzene
• What is the name for benzene with a nitro group?

  Nitrobenzene
• What is phenol?

  Benzene with a hydroxy group
• What is the name for benzene with an amine group?

  Phenylamine
• What type of reaction do arenes undergo?

  Electrophilic substitution
• Why do arenes not undergo addition reactions?

  They would disrupt the delocalized structure
• Who developed the Friedel-Crafts reaction?

  Charles Friedel and James Crafts
• What are the two types of reactions for arenes mentioned?

  Friedel-Crafts acylation and nitration
• What is the role of the halogen carrier in Friedel-Crafts acylation?

  To create a stronger electrophile
• What is formed when an acyl chloride reacts with a halogen carrier?

  A strong positive electrophile
• What happens to the benzene structure during Friedel-Crafts acylation?

  The ring becomes weaker for modification
• How do delocalized electrons in benzene react with electrophiles?

  They form a bond with the electrophile
• What is the result of the electrophilic substitution reaction in benzene?

  A new substituent replaces a hydrogen
• What is the purpose of reflux in the Friedel-Crafts reaction?

  To prevent loss of volatile substances
• What is the product of Friedel-Crafts acylation?

  A phenyl ketone
• What is the significance of the delocalized structure in benzene?

  It contributes to benzene's stability
• Why is benzene considered an important chemical in pharmaceuticals?

  It is used in many drug formulations
• What happens to the stability of benzene when an electrophile attacks?

  The stability is temporarily disrupted
• What is the role of acyl chlorides in Friedel-Crafts reactions?

  They provide the acyl group