Alkene, Conjugated Diene, and Alkyne Reactions

Comprehensive vocabulary flashcards covering reaction mechanisms, reagents, regiochemistry, and stereochemistry for alkenes, conjugated dienes, and alkynes.

Alkene Catalytic Hydrogenation ($H_2$ with $Pd$ or $Pt$)

The reduction of an alkene to an alkane via syn addition, adding two hydrogen atoms to the same face of the double bond.

Alkene Hydrohalogenation ($HX$)

The electrophilic addition of hydrogen halide ($HX$) across an alkene double bond following Markovnikov addition, where the halide ($X$) bonds to the more substituted carbon atom.

Alkene Acid-Catalyzed Hydration ($H^+ / H_2O$)

The addition of water across an alkene in the presence of an acid catalyst via Markovnikov addition, attaching a hydroxyl group ($OH$) to the more substituted carbon to yield an alcohol.

Alkene Halogenation ($X_2$)

The addition of molecular halogen ($X_2$) across an alkene double bond proceeding via anti or trans addition to yield a vicinal dihalide.

Hydroboration-Oxidation of Alkenes ($1)\;BH_3,\; 2)\;OH^- / H_2O_2$)

A two-step hydration reaction that proceeds with syn addition and anti-Markovnikov addition, placing the hydroxyl group ($OH$) on the less substituted carbon of the alkene.

Syn Dihydroxylation ($KMnO_4,\; OH^-$)

The reaction of an alkene with cold, alkaline potassium permanganate ($KMnO_4,\; OH^-$) via syn addition to form a 1,2-diol (vicinal cis-diol).

Permanganate Oxidative Cleavage ($KMnO_4,\; H^+$)

The vigorous oxidative cleavage of an alkene using acidic potassium permanganate, cleaving the ring of 1-methylcyclohexene to produce a keto-acid (containing both a ketone and a carboxylic acid).

Oxidative Ozonolysis ($1)\;O_3,\; 2)\;H_2O_2$)

The oxidative cleavage of an alkene using ozone followed by hydrogen peroxide ($H_2O_2$) workup, cleaving the double bond to generate a keto-acid.

Reductive Ozonolysis ($1)\;O_3,\; 2)\;Zn,\; H^+$)

The cleavage of an alkene using ozone followed by a reducing agent ($Zn,\; H^+$), cleaving the double bond of 1-methylcyclohexene to yield a keto-aldehyde.

1,2-Addition to Conjugated Dienes

An electrophilic addition across a conjugated diene (such as $HCl$ reacting with 1,3-butadiene) where the electrophile and nucleophile add to adjacent carbons ($C1$ and $C2$), yielding $H_3C-CH(Cl)-CH=CH_2$.

1,4-Addition to Conjugated Dienes

An electrophilic addition across a conjugated diene where addition occurs across terminal positions ($C1$ and $C4$) with the double bond shifting between $C2$ and $C3$, yielding $H_3C-CH=CH-CH_2Cl$.

Diels-Alder Reaction

A cycloaddition reaction between a conjugated diene (such as 1,3-butadiene) and a dienophile (such as ethylene, $CH_2=CH_2$) to produce a cyclohexene ring.

Alkyne Hydrohalogenation ($HX$)

The addition of hydrogen halide across an alkyne via one molar equivalent anti addition, which with excess reagent yields a geminal dihalide ($H_3C-CX_2-CH_3$).

Alkyne Halogenation ($X_2$)

The addition of molecular halogen across an alkyne via one molar equivalent anti addition, which upon further addition produces a tetrahaloalkane ($CH(Br)_2-C(Br)_2-CH_3$).

Complete Alkyne Hydrogenation ($H_2,\; Pt$)

The exhaustive reduction of an alkyne to an alkane ($H_3C-CH_2-CH_3$) using hydrogen gas in the presence of a platinum ($Pt$) catalyst.

Lindlar Catalytic Hydrogenation ($H_2\text{, Lindlar catalyst}$)

The stereoselective partial hydrogenation of an alkyne using poisoned Lindlar catalyst and hydrogen gas via syn addition to yield a cis-alkene.

Dissolving Metal Reduction of Alkynes ($Na,\; NH_3$)

The reduction of an alkyne using sodium in liquid ammonia proceeding via trans addition to yield a trans-alkene.

Mercuric-Catalyzed Alkyne Hydration ($H_2O,\; H_2SO_4,\; HgSO_4$)

The Markovnikov addition of water across an alkyne catalyzed by mercuric sulfate in acid, forming an enol that tautomerizes into a methyl ketone ($H_3C-C(=O)-CH_3$).

Alkylation of Terminal Alkynes ($NaNH_2\text{, then } RX$)

A two-step synthetic process in which a strong base ($NaNH_2$) deprotonates a terminal alkyne to form an acetylide anion ($Na^+\;^-C\equiv C-CH_3$), followed by nucleophilic substitution with an alkyl halide ($RX$) to create an internal alkyne ($R-C\equiv C-CH_3$).

Markovnikov Addition

A regiochemical pathway where an electrophile adds to the less substituted carbon atom of an alkene or alkyne, directing the incoming nucleophile to the more substituted carbon atom.

Anti-Markovnikov Addition

A regiochemical outcome in which the functional group or nucleophile attaches to the less substituted carbon of a multiple bond.

Syn Addition

A stereochemical addition pathway where both incoming substituents bond to the same face of a double or triple bond.

Anti Addition

A stereochemical addition pathway where two incoming substituents bond to opposite faces of a double or triple bond, also known as trans addition.