Methyl anion Lewis structure

Draw Lewis structures for methyl anion, ammonia and hydronium cation. How many electrons are left over in each after all bonds have been made Display and compare electron density surfaces for methyl anion, ammonia and hydronium cation. Which is the smallest molecule Which is the largest Rationalize your observation. (Hint Compare the number of electrons in each molecule, and the nuclear charge on the central atom in each molecule.)... 

Aldol addition and related reactions of enolates and enolate equivalents are the subject of the first part of Chapter 2. These reactions provide powerful methods for controlling the stereochemistry in reactions that form hydroxyl- and methyl-substituted structures, such as those found in many antibiotics. We will see how the choice of the nucleophile, the other reagents (such as Lewis acids), and adjustment of reaction conditions can be used to control stereochemistry. We discuss the role of open, cyclic, and chelated transition structures in determining stereochemistry, and will also see how chiral auxiliaries and chiral catalysts can control the enantiose-lectivity of these reactions. Intramolecular aldol reactions, including the Robinson annulation are discussed. Other reactions included in Chapter 2 include Mannich, carbon acylation, and olefination reactions. The reactivity of other carbon nucleophiles including phosphonium ylides, phosphonate carbanions, sulfone anions, sulfonium ylides, and sulfoxonium ylides are also considered. 

In the complex anion of a 1 1 complex, one Lewis acid R3AI is coordinated to the Lewis base, i. e., the fluoride anion. In the complex anion of a 1 2 complex on the other hand, two R3AI units are coordinated to the fluoride anion. The crystal structures of two of the 1 2 complexes of KF with R3AI are known, with R = Me and Et [5, 153). In both compounds, the fluorine atom is bound to two A1 atoms, the Al-F-Al angle equals 180°, and the Al-F bond length is 1.782 A in the methyl complex [118] and 1.820 A in the ethyl compound. The coordination geometry of A1 in both cases is tetrahedral, see Fig. 2. 

Cationic polymerization is the direct analogue of anionic polymerization but with a cation at the terminus of the growing polymer chain. Initiators are either strong acids such as sulfuric, perchloric, or hydrochloric acids, or Lewis acids such as BF3 or T1CI4. Usually the Lewis acids require water or methanol as a "cocatalyst", suggesting that the reactive initiator is actually a protic acid. The list of viable monomers is somewhat limited, including isobutene, methyl vinyl ether, and butadiene—all structures that can give stabilized cations. Cationic polymerizations are the least common of the types discussed here. 

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