Alkene Synthesis by Dehydration of Alcohols – Dehydration of alcohols is a common method for making alkenes. The word dehydration literally means “removal of water.” – Dehydration is reversible, and in most cases the equilibrium constant is not large. – In fact, the reverse reaction (hydration) is a method for …
Read More »Alkene Synthesis by Elimination of Alkyl Halides
Alkene Synthesis by Elimination of Alkyl Halides – Dehydrohalogenation is the elimination of a hydrogen and a halogen from an alkyl halide to form an alkene. – dehydrohalogenation can take place by the E1 and E2 mechanisms. – The second-order elimination (E2) is usually better for synthetic purposes because the …
Read More »Physical Properties of Alkenes
Physical Properties of Alkenes (1) Boiling Points and Densities – Most physical properties of alkenes are similar to those of the corresponding alkanes. – For example, the boiling points of but-1-ene, cis-but-2-ene, trans-but-2-ene, and n-butane are all close to 0 °C. – Also like the alkanes, alkenes have densities around …
Read More »Stability of Alkenes
Stability of Alkenes – In making alkenes, we often find that the major product is the most stable alkene. – Many reactions also provide opportunities for double bonds to rearrange to more stable isomers. – Therefore, we need to know how the stability of an alkene depends on its structure. …
Read More »Commercial Importance of Alkenes
Commercial Importance of Alkenes – Because the carbon–carbon double bond is readily converted to other functional groups, alkenes are important intermediates in the synthesis of polymers, drugs, pesticides, and other valuable chemicals. – Ethylene is the organic compound produced in the largest volume, at around 160 billion pounds per year …
Read More »Nomenclature of Alkenes
Nomenclature of Alkenes – Simple alkenes are named much like alkanes, using the root name of the longest chain containing the double bond. The ending is changed from -ane to -ene. – For example, (ethane) becomes “ethene,” (propane) becomes “propene,” and “cyclohexane” becomes “cyclohexene”. – When the chain contains more …
Read More »Elements of Unsaturation
Elements of Unsaturation (1) Elements of Unsaturation in Hydrocarbons – Alkenes are said to be unsaturated because they are capable of adding hydrogen in the presence of a catalyst. – The product, an alkane, is called saturated because it cannot react with any more hydrogen. – The presence of a …
Read More »The Orbital Description of the Alkene Double Bond
The Orbital Description of the Alkene Double Bond – In a Lewis structure, the double bond of an alkene is represented by two pairs of electrons between the carbon atoms. – The Pauli exclusion principle tells us that two pairs of electrons can go into the region of space between …
Read More »Acids and Bases – Online MCQ test
Online MCQ test on Acids and Bases – In this topic we offer you, online MCQ test in the fundmental of Acids and Bases . – It is a simple test to measure the strength of your knowledge in the basics of understanding the topics of Acids and Bases – …
Read More »Reactions of Alkyl Halides
In this subject we will discuss the Reactions of Alkyl Halides with chemical equations and examples Introduction to 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 …
Read More »Predicting SN1 SN2 E1 E2 reactions
Predicting the mechanisms: SN1, SN2, E1, E2 reactions – In this subject we will learn how to predict the the mechanisms of SN1, SN2, E1, E2 reactions – Given a set of reagents and solvents, how can we predict what products will result and which mechanisms will be involved? – …
Read More »Comparison of E1 and E2 reactions
Comparison of E1 and E2 Elimination Mechanisms – Let’s summarize the major points to remember about the E1 and E2 reactions, focusing on the factors that help us predict which of these mechanisms will operate under a given set of experimental conditions. Then we will organize these factors into a …
Read More »Stereochemistry of the E2 Reaction
Stereochemistry of the E2 Reaction – In this subject Stereochemistry of the E2 Reaction will be discussed – Like the SN2 reaction, the E2 reaction follows a concerted mechanism: Bond breaking and bond formation take place at the same time, and the partial formation of new bonds lowers the energy …
Read More »Thermochemistry – online MCQ test
Online MCQ test on Thermochemistry – In this topic we offer you, online MCQ test in the fundmental of Thermochemistry. – It is a simple test to measure the strength of your knowledge in the basics of understanding the topics of Thermochemistry – The test consists of only (15) questions …
Read More »Nuclear Chemistry – online MCQ test
Online MCQ test in Nuclear Chemistry – In this topic we offer you, online MCQ test in the fundmental of Nuclear Chemistry. – It is a simple test to measure the strength of your knowledge in the basics of understanding the topics of Nuclear Chemistry – The test consists of …
Read More »E2 Reaction : Second-Order Elimination
Second-Order Elimination: The E2 Reaction – Eliminations can also take place under second-order conditions with a strong base present. – As an example, consider the reaction of tert-butyl bromide with methoxide ion in methanol. – This is a second-order reaction because methoxide ion is a strong base as well as …
Read More »Zaitsev’s Rule : Positional Orientation of Elimination
Positional Orientation of Elimination: Zaitsev’s Rule – In this subject , Positional Orientation of Elimination: Zaitsev’s Rule will be discussed – Many compounds can eliminate in more than one way, to give mixtures of alkenes. – In many cases, we can predict which elimination product will predominate. – In the …
Read More »E1 Reaction : First-Order Elimination
First-Order Elimination : The E1 Reaction – An elimination involves the loss of two atoms or groups from the substrate, usually with formation of a pi bond. – Elimination reactions frequently accompany and compete with substitutions. – By varying the reagents and conditions, we can often modify a reaction to …
Read More »Comparison of SN1 and SN2 Reactions
Comparison of SN1 and SN2 Reactions Let’s compare what we know about the SN1 and SN2 Reactions and reactions, the organize this material into a brief table. (1) Effect of the Nucleophile on SN1 and SN2 Reactions – The nucleophile takes part in the slow step (the only step) of …
Read More »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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