Organic Chemistry Course (CHEM 0901)

A comprehensive online course designed to bridge the gap between CSEC (Caribbean Secondary Education Certificate) and university-level chemistry. It covers four main branches of chemistry: Organic, General, Inorganic, and Physical. After mastering this course, students can access advanced levels within chemistry or other disciplines.

The first episode in the 'Organic Chemistry' series. It lays the foundation for understanding basic concepts and terminology in organic chemistry. This sets the stage for deeper exploration in later episodes.

The series of steps involved in a chemical reaction, showing the movement of electrons and the formation and breaking of bonds. Understanding this helps predict how molecules interact.

Types of hydrocarbons, which are compounds made of only carbon and hydrogen atoms. Each has a different structure that influences its properties and reactivity. Alkanes, with only single bonds, are less reactive, while alkenes and alkynes with double and triple bonds are more reactive.

Short-lived, unstable molecules that are formed during the reaction. They are crucial in the course of a reaction and often determine its outcome. Examples include carbocations and carbanions.

At lower temperatures, enthalpy dominates, favoring addition reactions. At higher temperatures, entropy dominates, favoring elimination reactions.

The process of adding hydrogen (H2) across a carbon-carbon double bond (C=C) using a metal catalyst. This converts an alkene to an alkane.

Hydrogenation is stereospecific, meaning only 'syn' addition is observed. This means the hydrogen atoms add to the same side of the double bond.

A metal catalyst is essential for hydrogenation because it lowers the activation energy, speeding up the reaction. Without it, the reaction is too slow.

The metal surface of the catalyst binds both H2 and the alkene, enabling the 'syn' addition of hydrogen atoms across the pi bond.

A chemical reaction where two halogen atoms are added across a carbon-carbon double bond.

Halogenation is a crucial step in the manufacturing process of polyvinyl chloride (PVC).

Halogenation occurs with anti addition, meaning the halogens add to opposite sides of the double bond.

A cyclic intermediate formed during halogenation with bromine, where the bromine is bonded to two carbons of the former double bond.

Halogenation exhibits stereoselectivity, resulting in only anti addition products. This is because the mechanism involves a bromonium ion intermediate, not a carbocation.

A process where an alkyne is converted to an alkane through the addition of two equivalents of hydrogen gas (H2). This occurs through a two-step addition process, with the first addition generating a cis alkene and the second yielding the alkane.

A deactivated or poisoned catalyst used to selectively stop the hydrogenation of an alkyne at the cis alkene stage, preventing further reduction to an alkane. Common examples include Lindlar's catalyst and P-2 (Ni2B complex-Nickel Boride).

A method to reduce an alkyne to a trans alkene using sodium metal and ammonia. This reaction is stereoselective for anti addition of H and H, resulting in the trans configuration.

Chemical reactions where a molecule is added to an unsaturated compound, like an alkene, to break the double bond and create new sigma bonds. The pi bond acts as an electron-pair donor.

These are equilibrating reactions, meaning they can proceed in both directions, with the favored side dependent on temperature. Higher temperatures favor entropy, making elimination more prominent.

In addition reactions, the pi bond (double bond) acts as an electron-pair donor, attracting the electrophile (electron-seeking species).

During catalytic hydrogenation, hydrogen atoms are added to the same side (syn) of the double bond, resulting in a cis arrangement in the product alkene.

In dissolving metal reduction, hydrogen atoms are added to opposite sides (anti) of the double bond, resulting in a trans arrangement in the product alkene.

A regioselective reaction favors the formation of one particular regioisomer over others. In the context of hydrohalogenation, this means that the H atom and X atom will preferentially attach to specific carbons in the alkene, leading to a specific product.

Markovnikov's rule states that in the addition of HX to an unsymmetrical alkene, the hydrogen atom preferentially adds to the carbon with more hydrogen atoms already attached, while the halogen atom adds to the carbon with fewer hydrogen atoms.

Markovnikov's rule is explained by the formation of carbocations as intermediates. Tertiary carbocations, with three carbon substituents, are more stable than secondary carbocations, with two carbon substituents. This stability difference determines the regioselectivity of the reaction, driving the addition of H to the carbon that leads to a more stable carbocation.

The presence of peroxides with HBr leads to a radical mechanism, which results in the anti-Markovnikov product. The bromine atom adds to the carbon with more hydrogen atoms, while the hydrogen atom adds to the carbon with fewer hydrogen atoms.

In the absence of peroxides, the reaction proceeds via a carbocation intermediate, leading to Markovnikov addition. In the presence of peroxides, a radical mechanism is involved, resulting in anti-Markovnikov addition.

The regioselectivity of HBr addition to an alkene can be controlled by the presence or absence of peroxides. Peroxides promote a radical mechanism, leading to anti-Markovnikov addition, while the absence of peroxides promotes a carbocation-based mechanism, resulting in Markovnikov addition.

To predict the major product, consider the structure of the alkene, the identity of the haloacid (HX), and the presence or absence of peroxides. If the alkene is symmetrical, only one product is possible. If the alkene is unsymmetrical, apply Markovnikov's rule or its reverse depending on the presence or absence of peroxides.

The major product will be 1-bromo-2-methylpropane. This is due to the anti-Markovnikov addition that occurs in the presence of peroxides. The bromine atom adds to the less substituted carbon, while the hydrogen atom adds to the more substituted carbon.