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Rearrangements in the SN1 Reactions

Rearrangements in the SN1 Reactions

Rearrangements in the SN1 Reactions – Carbocations frequently undergo structural changes, called rearrangements, to form more stable ions. – A rearrangement may occur after a carbocation has formed or it may occur as the leaving group is leaving. – Rearrangements are not seen in SN2 reactions, where no carbocation is …

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Stereochemistry of the SN1 Reactions

Stereochemistry of the SN1 Reaction – The SN2 reaction is stereospecific: the nucleophile attacks from the back side of the electrophilic carbon atom, giving inversion of configuration. – In contrast, the SN1 reaction is not stereospecific. – In the SN1 mechanism, the carbo-cation intermediate is sp2 hybridized and planar. – …

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SN2 reaction of Alkyl halides

SN2 reaction of Alkyl halides

In this subject Second-Order Nucleophilic Substitution: The SN2 Reaction of Alkyl halides will be discussed Reactions of Alkyl Halides: Substitution and Elimination – Alkyl halides are easily converted to many other functional groups. – The halogen atom can leave with its bonding pair of electrons to form a stable halide …

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Preparation of alkyl halides

Preparation of alkyl halides – Most Methods of preparation of alkyl halides exploit the chemistry of functional groups we have not yet covered. – For now, we review free-radical halogenation and only summarize other, often more useful, syntheses of alkyl halides. – The other Methods of preparation of alkyl halides …

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Physical Properties of Alkyl Halides

Physical Properties of Alkyl Halides will be discussed such as dipole moment, London force, Dipole–dipole attractions, densities of common alkyl halides. Structure of Alkyl Halides – In an alkyl halide, the halogen atom is bonded to an carbon atom. – The halogen is more electronegative than carbon, and the bond …

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Nomenclature of Alkyl Halides

Introduction to Alkyl Halides – In this subject , we consider Nomenclature of alkyl halides. – Our study of organic chemistry is organized into families of compounds classified by their functional groups. – We use alkyl halides to introduce substitution and elimination, two of the most important types of reactions …

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Essential terms in Stereochemistry

Essential terms in Stereochemistry

Essential terms in Stereochemistry stereochemistry – stereochemistry is The study of the three-dimensional structure of molecules. – It is the systematic presentation of a specific field of science and technology that traditionally requires a short preliminary excursion into history. – Stereochemistry is the (chemistry of space). – In this subject …

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Resolution of Enantiomers

Resolution of Enantiomers

Resolution of Enantiomers – Pure enantiomers of optically active compounds are often obtained by isolation from biological sources. – Most optically active molecules are found as only one enantiomer in living organisms. – For example, pure (+)-tartaric acid can be isolated from the precipitate formed by yeast during the fermentation …

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Physical Properties of Diastereomers

Physical Properties of Diastereomers

What is Diastereomers? – We have defined stereoisomers as isomers whose atoms are bonded together in the same order but differ in how the atoms are directed in space. – We have also considered enantiomers (mirror-image isomers) in detail. – All other stereoisomers are classified as diastereomers, which are defined …

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Meso Compounds

Meso Compounds – Compounds that are achiral even though they have asymmetric carbon atoms are called meso compounds. – The (2R,3S) isomer of 2,3-dibromobutane is a meso compound. – most meso compounds have this kind of symmetric structure, with two similar halves of the molecule having opposite configurations. – In …

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Chiral Compounds without Asymmetric Atom

Chiral Compounds without Asymmetric Atoms – Most chiral organic compounds have at least one asymmetric carbon atom. – Some compounds are chiral because they have another asymmetric atom, such as phosphorus, sulfur, or nitrogen, serving as a chirality center. – Some compounds are chiral even though they have no asymmetric …

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What is Diastereomers?

Diastereomers – We have defined stereoisomers as isomers whose atoms are bonded together in the same order but differ in how the atoms are directed in space. – We have also considered enantiomers (mirror-image isomers) in detail. – All other stereoisomers are classified as diastereomers, which are defined as stereoisomers …

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Drawing Fischer Projections

In this subject we will discuss How to draw Fischer projections Introduction to Fischer Projections – We have been using dashed lines and wedges to indicate perspective in drawing the stereochemistry of asymmetric carbon atoms. – When we draw molecules with several asymmetric carbons, perspective drawings become time consuming and …

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Racemic Mixtures

Racemic Mixtures – Suppose we had a mixture of equal amounts of (+)-butan-2-ol and (-)-butan-2-ol – The (+) isomer would rotate polarized light clockwise with a specific rotation of +13.5o ,and the isomer (-) would rotate the polarized light counterclockwise by exactly the same amount. – We would observe a …

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Biological Discrimination of Enantiomers

Biological Discrimination of Enantiomers – If the direction of rotation of polarized light were the only difference between enantiomers, one might ask whether the difference would be important. – Biological systems commonly distinguish between enantiomers, and two enantiomers may have totally different biological properties. – In fact, any chiral probe …

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