SM-Educate Chemistry

  Markovnikov's Rule: Why Some Alkenes React Faster Than Others If you've ever wondered why HBr adds to an alkene in one specific way and not randomly, this is the rule that explains it — and once you understand why it happens (not just the rule itself), you'll never mix it up again. The Rule Itself When a protic acid (like HBr, HCl, or H₂SO₄) adds across a double bond, the hydrogen ends up on the carbon that already has more hydrogens , and the other group (Br, Cl, etc.) ends up on the more substituted carbon. The old-school phrasing: "the rich get richer" — the carbon with more H's gets even more H's. But Why Does This Happen? This is where most textbooks stop, and where most confusion starts. The real reason is about carbocation stability , not some arbitrary rule to memorize. Here's the mechanism: The acid's H⁺ attacks the double bond first This creates a carbocation on one of the two former double-bond carbons Br⁻ then attacks t...

SN1 vs SN2: How to Tell Which Mechanism You're Looking At These four letters cause more confusion than almost anything else in organic chemistry — not because the mechanisms are hard individually, but because students never learn a reliable way to decide which one they're looking at under exam pressure. Here's a clean way to tell them apart, every time. The basics first SN1 = Substitution, Nucleophilic, Unimolecular (rate depends on only 1 species) SN2 = Substitution, Nucleophilic, Bimolecular (rate depends on 2 species) That's literally what the numbers mean — not "1 step" and "2 steps," which is the most common misconception. It's about how many molecules are involved in the rate-determining step. SN2: the one-step story SN2 happens in a single, smooth motion — the nucleophile attacks from the opposite side of the leaving group at the exact same time the leaving group departs. No intermediate forms. Rate = k[substrate][nucleo...

The 5 Hardest Mechanisms to Draw | Organic Chemistry Challenge | SM-EDUCATE Chemistry 🧪 SM-EDUCATE CHEMISTRY June 07, 2026 The 5 Hardest Mechanisms to Draw (And Why They Work) ✍️ Arrow‑pushing challenges · Pericyclic · Rearrangements · Peer discussion 📤 SHARE Organic Chemistry Reaction Mechanisms Arrow Pushing Pericyclic Reactions Carbocation Rearrangements Advanced Chemistry Arrow‑pushing is the language of organic chemistry. But some mechanisms make even seasoned chemists pause. The electrons seem to move in impossible ways, bonds break and form simultaneously, and stereochemistry flips unexpectedly. Here are five of the hardest mechanisms to draw correctly — and the physical principles that make them work. 1. Cope Rearrangement ([3,3]-sigmatropic) How do you draw arrows for a reaction where three σ bonds break and three π bonds f...