Organic Chemistry

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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Optical Activity in Organic Compounds

– Rotation of the plane of polarized light is called optical activity, and substances that rotate the plane of polarized light are said to be optically active. – There are alot of Organic Compounds have optical activity Introduction to Optical activity Mirror-image molecules have nearly identical physical properties. Compare the …

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(R) and (S) of Asymmetric Carbon Atoms

(R) and (S) Nomenclature of Asymmetric Carbon Atoms – Alanine is one of the amino acids found in common proteins. – Alanine has an asymmetric carbon atom, and it exists in two enantiomeric forms. – These mirror images are different, and this difference is reflected in their biochemistry. – Only …

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Chirality in Organic Chemistry

What is Chirality? – What is the difference between your left hand and your right hand? They look similar, yet a left-handed glove does not fit the right hand. – The same principle applies to your feet. They look almost identical, yet the left shoe fits painfully on the right …

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Cyclohexane: Axial and Equatorial Bonds in Cyclohexane

– In this subject, we will discuss the Substituted Cyclohexane: Axial and Equatorial Hydrogen Groups Substituted Cyclohexane: Axial and Equatorial Hydrogen Groups – The six-membered ring is the most common ring found among nature’s organic molecules. – For this reason, we shall give it special attention. – We have already …

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Conformations of Cyclohexane: The Chair and the Boat

– In this subject, we will discuss Conformations of Cyclohexane: The Chair and the Boat Conformations of Cyclohexane: The Chair and the Boat Cyclohexane is more stable than the other cycloalkanes we have discussed, and it has several conformations that are important for us to consider. (1) The most stable conformation …

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Acidity of Carboxylic Acids and Alcohols

– In this subject, we will discuss the Acidity Differences between Alcohols and Carboxylic Acids Acidity of Carboxylic Acids and Alcohols – Carboxylic acids are weak acids, typically having pKa values in the range of 3–5. – Alcohols, by comparison, have pKa values in the range of 15–18 and essentially do …

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Thermodynamics of Organic Compounds

– In this subject, we will discuss the Thermodynamics of Organic Compounds Thermodynamics of Organic Compounds – For a reaction to be practical, the equilibrium must favor the products, and the reaction rate must be fast enough to form them in a reasonable time. – These two conditions depend on …

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Lewis Acids and Lewis Bases

Lewis Acids and Lewis Bases

– In this subject, we will discuss the Lewis acid-base theory and Lewis Acids and Lewis Bases  Lewis Acids and Lewis Bases – In 1923 G. N. Lewis proposed a theory that significantly broadened the understanding of acids and bases. – As we go along we shall find that an …

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