CHEM 3331 1nd Edition Lecture 19Outline of Last Lecture I. Electrophilic AdditionII. Addition of HXIII. Addition of H2OIV. OxymercurationV. HydroborationVI. Addition of HalogensOutline of Current Lecture I. Addition of Halogens (continued)II. HydrogenationIII. EpoxidationIV. DihydroxylationV. Oxidative CleavageVI. PolymerizationCurrent LectureI. Addition of Halogens (continued)When the bromines are added on opposite sides it is anti-addition. When they are attached on the same side it is addition. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.HalohydrinsWith the addition of water, the negative Br atom should attack the positive carbon. H2O acts as a solvent, in large amounts the H2O can react faster than the remaining Br-.The OH and X are on opposite sides. II. HydrogenationThis the addition of H2 to an alkene. This requires a catalyst such as Pd and Pt. The hydrogen attaches to the surface of the catalyst. This creates a syn-addition.III. EpoxidationThis requires that a peroxy acid attaches to an alkene. The three most commonly used are peroxyacetic acid, peroxybenzoic acid, and most commonly mCPBA. It keeps stereochemistry. Cis is more stable. IV. DihydroxylationAnti- dihydroxylationWe take our epoxide from the previous reaction and add an acid to it.This creates a trans molecule. Syn-dihydroxylationThe most common form is to start with an alkene and add OsO4 and H2O2 to it to create a cis-molecule. This gives a 70% yield of our major product. However, using KMnO4 we only achieve 50% of our major product.V. Oxidative CleavageThe remaining 50% using KMnO4 goes through oxidative cleavage. VI. PolymerizationMonomer (monomer)n polymerThis works with radicals and anions as well. Polystyrene is an example of polymerization of
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