Hydrocarbons and Fats Lecture Notes

Introduction

• Alkanes, Methane, Propane, Butane
  • Saturated hydrocarbons, single-bond carbon chains
  • Basic, add another carbon to lengthen the chain
  • Fuel sources, but also present in food (e.g., fats)

Fats

• Types and Terminology
  • Saturated, Mono, Polyunsaturated, Omega-3, Hydrogenated, Trans fats
  • Differences among fats due to the presence and type of double/triple bonds

Saturated vs. Unsaturated Hydrocarbons

• Saturated Hydrocarbons (Alkanes)
  • Maximum number of bonds (4 per carbon)
  • Stable
• Unsaturated Hydrocarbons
  • Double/Triple bonds between carbons
  • Forms new classes of hydrocarbons
    • Alkenes: Double bonds
    • Alkynes: Triple bonds
    • Naming Trick: Alkane, Elkene, Ylkynes (Alphabetical order)
    • Naming Conventions:
      • Double bonds end in "-ene"
      • Triple bonds end in "-yne"
      • Follow typical alkane prefix rules (e.g., Propene, Propyne)

Structure and Isomerism

• Single Bonds (Sigma bonds)
  • Can rotate freely
• Double Bonds (Sigma + Pi bonds)
  • Restricted rotation
  • Leads to Cis-Trans Isomerism
• Example: 2-Butene
  • Cis-2-butene: Methyl groups same side
  • Trans-2-butene: Methyl groups opposite sides
  • Cannot switch between cis and trans without breaking bonds
• Triple Bonds (Sigma + 2 Pi bonds)
  • No rotation, no isomerism for alkynes

Reactions Involving Double and Triple Bonds

• Pi Bonds
  • More unstable than sigma bonds
  • Open and allow for various addition reactions
  • Addition Reactions: Atoms added across double/triple bonds
    • Hydrogenation: Adding hydrogen (H2); requires catalyst
    • Halogenation: Adding halogens (e.g., bromine)
    • Hydration: Adding water
    • Oxygenation: Adding oxygen
• Outcome: Convert unsaturated hydrocarbons to saturated

Application to Fats

• General Structure
  • Triglycerides: Composed of three fatty acids bonded to glycerol
  • Fatty acids are long hydrocarbon chains (alkanes/alkenes, rarely alkynes)
• Saturated Fats:
  • No double bonds
  • Stable, longer shelf life
  • Solid at room temperature, harder to digest
• Hydrogenated Oils
  • Polyunsaturated: Many double bonds, liquid at room temp
  • Hydrogenation: Converts to saturated fats (spreadable, stable)
  • Partial Hydrogenation: Mono-unsaturated fats (one double bond)
• Omega-3 Fats
  • Double bond 3 carbons from the omega (end) of the chain
  • Essential for survival, must be ingested
• Trans Fats
  • Unsaturated fats with trans isomerism
  • Act like saturated fats; difficult to breakdown
  • Result from partial hydrogenation of vegetable oils

Summary

• Key Points
  • Hydrocarbons: Alkanes (single bonds), Alkenes (double bonds), Alkynes (triple bonds)
  • Naming and structural rules
  • Isomerism in alkenes: cis-trans
  • Key chemical reactions affecting hydrocarbons
  • Practical implications for fats: Saturated, unsaturated, trans, omega-3

Credits

• Written by: Edi Gonzalez
• Edited by: Blake de Pastino
• Chemistry Consultant: Dr. Heiko Langner
• Filmed, Edited, Directed by: Nicholas Jenkins
• Script Supervisor: Michael Aranda
• Graphics: Thought Cafe