Organic Chemistry Reagent & Pattern Guide (Chapters 8-10)

This set covers vocabulary, reagents, and reaction patterns for Alkenes, Alkynes, and Radical Reactions from Chapters 8-10 of Organic Chemistry.

Markovnikov Review

A rule stating that in the addition of $HX$ to an alkene, the $H$ adds to the carbon with more hydrogen atoms, while the $X$ (halogen or $OH$) ends on the more substituted carbon.

Anti-Markovnikov

A regiochemical pattern where a substituent (like $OH$ or $Br$) is added to the less substituted carbon of a double or triple bond.

Syn Addition

A stereochemical description where two groups arrive and add to the same face of a molecule.

Anti Addition

A stereochemical description where two groups arrive and add to the opposite faces of a molecule.

Hydroboration-oxidation

A two-step reaction using $1.\text{ }BH_3 \times THF$ and $2.\text{ }H_2O_2, NaOH$ that adds $H$ and $OH$ in an anti-Markovnikov and syn fashion with no rearrangements.

Oxymercuration-demercuration

A sequence using $1.\text{ }Hg(OAc)_2, H_2O$ and $2.\text{ }NaBH_4, NaOH$ that results in a Markovnikov alcohol without carbocation rearrangement.

Halohydrin Formation

An anti addition reaction using $X_2/H_2O$ where $OH$ adds to the more substituted carbon and $X$ adds to the less substituted carbon of an alkene.

Vicinal Dihalide

A product formed by the anti addition of $Br_2$ or $Cl_2$ across an alkene, resulting in one halogen on each adjacent carbon.

Lindlar Catalyst

A poisoned catalyst used in the hydrogenation of alkynes ($H_2$ with Lindlar) to perform a partial reduction, stopping at a syn (cis/Z) alkene.

Dissolving-Metal Reduction

A reaction using $Na, NH_3(l)$ to reduce an alkyne into a trans/E alkene through anti addition.

mCPBA ($RCO_3H$)

A peroxyacid reagent used to form a three-membered epoxide ring across a $C=C$ bond in a concerted reaction.

Reductive Ozonolysis

A process using $1.\text{ }O_3$ and $2.\text{ }DMS$ or $Zn/H_2O$ that cuts a $C=C$ bond to produce aldehydes or ketones.

Enol

An intermediate structure featuring a $C=C$ double bond with an $OH$ group directly attached, which typically tautomerizes into a more stable carbonyl.

Tautomerization

The chemical equilibrium process by which an enol converts into a more stable ketone or aldehyde.

Acetylide Ion

A species formed by treating a terminal alkyne with $NaNH_2$, which can затем perform an $S_N2$ reaction to lengthen the carbon chain.

Radical Initiation

The first step in a radical chain reaction where zero radicals are converted into two radicals, often induced by heat or light ($h\nu$).

Radical Propagation

The repeating step in a radical chain reaction where one radical enters and one radical leaves as a product.

Radical Termination

The final step in a radical chain reaction where two radicals couple to form zero radicals, stopping the chain.

NBS (N-Bromosuccinimide)

A reagent used with $h\nu$ or heat for allylic bromination, specifically replacing an allylic $H$ with $Br$ while avoiding high $Br_2$ concentrations.

Fishhook Arrows

Specialized reaction arrows used in radical mechanisms to represent the movement of exactly one electron.

Allylic Position

The carbon atom located directly adjacent to a $C=C$ double bond; radicals at this position are resonance-stabilized.

Antioxidants (BHT, BHA, hydroquinone)

Radical inhibitors that stop chain propagation by donating an $H$ atom to form a stabilized radical that does not react rapidly.

Autooxidation

A radical chain process where $O_2$ reacts with $C-H$ bonds (especially allylic/benzylic) to form hydroperoxides ($ROOH$).

Hydrocracking

An industrial radical process that uses $H_2$ and heat to break large alkanes into smaller alkanes.

Peroxide Effect

The phenomenon where using $HBr$ with $ROOR$ (peroxides) leads to anti-Markovnikov addition of $Br$ via a radical mechanism; only $HBr$ shows this effect.