Last Minute Lecture

SN1 vs SN2 Substitution Reactions Explained — Mechanisms, Factors, and Stereochemistry | Chapter 9 of Klein Organic Chemistry as a Second Language Substitution reactions are among the most important and most tested reactions in introductory organic chemistry. In Chapter 9 of Organic Chemistry as a Second Language: First Semester Topics by David Klein, students learn how to distinguish between SN1 and SN2 mechanisms and predict which pathway will dominate under a given set of conditions. This chapter synthesizes everything learned so far—mechanisms, stereochemistry, carbocations, nucleophiles, and solvents—into a practical decision-making framework that applies across the rest of the course. 🎥 Watch the video above for a clear, step-by-step breakdown of SN1 and SN2 substitution reactions and how to confidently predict reaction outcomes. What Are Substitution Reactions? In a substitution reaction, one group attached to a carbon atom—the leaving group—is replaced by anoth...

Organic Reaction Mechanisms Explained — Arrow Pushing, Nucleophiles, and Carbocation Rearrangements | Chapter 8 of Klein Organic Chemistry as a Second Language Reaction mechanisms are the logic engine of organic chemistry. In Chapter 8 of Organic Chemistry as a Second Language: First Semester Topics by David Klein, students learn how and why reactions occur by following the movement of electrons step by step. Rather than memorizing reactions as isolated facts, this chapter teaches mechanisms as unified problem-solving tools that make organic chemistry more intuitive, predictable, and easier to retain. 🎥 Watch the video above for a guided walkthrough of curved-arrow notation, reaction intermediates, and the core patterns that appear throughout organic chemistry. What Is a Reaction Mechanism? A reaction mechanism is a step-by-step depiction of how electrons move during a chemical reaction. Unlike resonance structures, which conceptually represent electron delocalization,...

Molecular Configuration and Chirality Explained — R/S, E/Z, and Stereoisomers in Organic Chemistry | Chapter 7 of Klein Organic Chemistry as a Second Language Configuration is where organic chemistry becomes truly three-dimensional. In Chapter 7 of Organic Chemistry as a Second Language: First Semester Topics by David Klein, students learn how fixed spatial arrangements of atoms create molecular handedness, stereoisomers, and profound differences in chemical behavior. This chapter introduces the language and logic of stereochemistry, building the foundation needed to understand reaction outcomes, biological activity, and molecular recognition. 🎥 Watch the video above for a clear, step-by-step breakdown of chirality, R/S assignment, stereoisomer classification, and Fischer projections. Configuration vs. Conformation Chapter 7 begins by drawing a critical distinction between conformation and configuration . While conformations arise from bond rotation and can interconve...

Conformational Analysis Explained — Newman Projections, Chair Conformations, and Molecular Stability | Chapter 6 of Klein Organic Chemistry as a Second Language Molecules are not static objects—they are flexible, constantly shifting between shapes as bonds rotate. In Chapter 6 of Organic Chemistry as a Second Language: First Semester Topics by David Klein, students are introduced to conformational analysis , a framework for understanding how molecular shape, energy, and stability influence chemical reactivity. This chapter marks a critical transition from static structures to dynamic molecules, giving students the tools to visualize motion in three dimensions and predict which molecular arrangements are favored. 🎥 Watch the video above for a clear, guided explanation of Newman projections, cyclohexane chair conformations, and how conformational energy affects organic reactions. What Are Conformations? Conformations are different spatial arrangements of a molecule that ...

Resonance in Organic Chemistry — Electron Delocalization and Arrow Pushing Explained | Chapter 2 of Klein Organic Chemistry as a Second Language Resonance is one of the most important—and most misunderstood—concepts in organic chemistry. In Chapter 2 of Organic Chemistry as a Second Language: First Semester Topics by David Klein, students learn how chemists represent delocalized electrons and why resonance is essential for understanding molecular stability, reactivity, and reaction mechanisms. This chapter builds directly on bond-line fluency from Chapter 1 and introduces a powerful conceptual framework that appears throughout the remainder of the course. 🎥 Watch the video above for a guided walkthrough of resonance structures, curved-arrow notation, and the rules that govern valid electron movement. What Is Resonance? Resonance is the method chemists use to depict molecules with delocalized electrons —electrons that cannot be accurately represented by a single Lewis s...

Acid–Base Reactions in Organic Chemistry — ARIO, pKa, and Reaction Prediction Explained | Chapter 3 of Klein Organic Chemistry as a Second Language Acid–base chemistry is the backbone of organic reactivity. In Chapter 3 of Organic Chemistry as a Second Language: First Semester Topics by David Klein, students learn how proton transfer reactions are governed by charge stability, electron distribution, and predictable structural trends. This chapter provides a conceptual toolkit for determining which protons are acidic, which bases are stable, and how to predict the direction of equilibrium—skills that reappear constantly in mechanisms throughout the course. 🎥 Watch the video above for a clear walkthrough of ARIO, pKa values, and how acid–base principles guide reaction prediction in organic chemistry. Why Acid–Base Reactions Matter Nearly every organic reaction involves acid–base behavior at some stage, whether explicit or hidden within a mechanism. Chapter 3 emphasizes t...

Molecular Geometry and Hybridization — Predicting 3D Structure in Organic Chemistry | Chapter 4 of Klein Organic Chemistry as a Second Language Molecular geometry determines how organic molecules behave in real space. In Chapter 4 of Organic Chemistry as a Second Language: First Semester Topics by David Klein, students learn how three-dimensional structure governs reactivity, stability, and interactions between molecules. This chapter builds on earlier foundations—bond-line drawings, resonance, and acid–base chemistry—by introducing the spatial logic that explains why some reactions occur easily while others are blocked by steric constraints. 🎥 Watch the video above for a clear, step-by-step explanation of hybridization, VSEPR theory, and how to quickly identify molecular geometry in organic chemistry problems. Why Molecular Geometry Matters Organic chemistry does not happen in two dimensions. The three-dimensional arrangement of atoms determines how molecules collide,...