CH-112 PPT Slides-Chapter 12 LibreText Fa23 (1)

Chapter Overview

• Chapter 12: Focus on Organic Chemistry: Unsaturated and Aromatic Hydrocarbons

Objectives of Chapters 11 – 14

• Distinguish between organic and inorganic molecules

• Name simple and branched alkanes

• Classify organic molecules by functional groups

• Predict polarity based on structure/formula

• Compare physical properties (solubility, melting & boiling points) based on structure & functional groups

• Write balanced combustion reactions for alkanes

• Draw structures of organic molecules from names/formulas including isomers

• Recognize chemical reactions in various organic functional groups

• Identify organic reaction types from equations

• Predict products of organic reactions from reactants

Hydrocarbons

Saturated vs. Unsaturated Hydrocarbons

• Saturated Hydrocarbons: Only single (C-C) bonds; maximum hydrogen atoms

• Unsaturated Hydrocarbons: At least one C=C double bond or C≡C triple bond

Alkenes

• Contain at least one C=C double bond

• Can be linear, cyclic, or branched

• Exhibit cis- and trans- stereoisomers due to rigid double bonds

  • Cis Isomer: Substituents on the same side of the double bond

  • Trans Isomer: Substituents on opposite sides

Stereoisomers of 2-Butene

• Differences in melting and boiling points due to spatial arrangement.

Cis-Trans Isomerism

• Cannot form cis-trans isomers if double bond carbons have identical groups

• Example of molecules that do not exhibit isomerism

Biochemical Example of Cis-Trans Isomers

• The role of retinal in vision, transitioning between 11-cis-retinal and all-trans-retinal

Practice Problems on Alkenes

• Drawing isomers and analyzing structural formulas

Alkynes

• Contain at least one C≡C triple bond

• Exhibit similar structural diversity (linear, cyclic, branched)

Reactions of Alkenes & Alkynes: Addition Reactions

• Reactive due to the ease of breaking double/triple bonds

• Addition reactions lead to saturation by turning double/triple bonds into single bonds

  • Hydrogenation: Adds hydrogen, converting unsaturated to saturated

Hydration Reactions

• Adding water to alkenes results in a change from C=C to C-C, affecting product structures

Aromatics

• A class of unsaturated hydrocarbons with rings of C atoms

• Exhibit resonance: alternating C-C single and C=C double bonds

• Example: Benzene (C6H6)

Examples of Aromatic Compounds

• Common compounds: Vanillin, Ibuprofen, Aspirin, Acetaminophen

Practice Problem on Unsaturated Hydrocarbons

• Identifying molecular types: alkane, alkene, alkyne, or aromatic

Answers to Practice Problems

• Review solutions for cis and trans isomer drawings, structural formula errors in reactions, and molecular classification.