Organic Chemistry: Reactions of Alkanes, Alkenes, and Alkynes

Vocabulary practice flashcards covering organic chemistry reactions of alkanes, alkenes, and alkynes, including addition mechanisms, regioselectivity, stereochemistry, oxidations, reductions, and polymerizations.

Halogenation of Alkanes ($\text{Alkane} + X_2$)

A radical substitution reaction where a hydrogen atom is replaced by a halogen ($X$); more substituted positions form more stable radicals, reacting more selectively but at a slower reaction rate.

Vicinal Dihalide (vic-dihalide)

A compound containing two halogen atoms bonded to adjacent carbon atoms, produced by the addition of $X_2$ across an alkene double bond.

Halogenation of Alkenes ($\text{Alkene} + X_2$)

An electrophilic addition reaction carried out in an inert solvent like $CCl_4$ that proceeds through a cyclic halonium ring intermediate (such as a bromonium ion) to provide stereospecific anti-addition yielding a vic-dihalide.

Hydrohalogenation of Alkenes ($\text{Alkene} + HX$)

A regioselective electrophilic addition following Markovnikov's rule, wherein the halide adds to the carbon atom that generates the more stable carbocation intermediate.

Peroxide-Promoted Hydrobromination ($\text{Alkene} + HBr\text{ in }H_2O_2$)

A free-radical addition reaction of $HBr$ across an alkene that yields an anti-Markovnikov product because the bromine radical ($Br\cdot$) is relatively stable.

Addition of Sulfuric Acid ($\text{Alkene} + H_2SO_4$)

An electrophilic addition across an alkene double bond where the proton attaches to one carbon while the other carbon receives the cation, creating an alkyl hydrogen sulfate with a good leaving group ($-OSO_3H$).

Acid-Catalyzed Hydration of Alkenes ($\text{Alkene} + H_2O$)

An addition reaction that follows Markovnikov's rule to create an alcohol through a carbocation intermediate ($C^+$), which can undergo carbocation rearrangement.

Allylic Bromination ($\text{Alkene} + \text{NBS}$)

A selective substitution reaction using N-bromosuccinimide (NBS) that installs a bromine atom at the allylic position without breaking the alkene's $\pi$ bond.

Halohydrin Formation ($\text{Alkene} + HOX$)

The reaction of an alkene with a halogen ($X_2$) in water with $CH_2Cl_2$ solvent; yields a halohydrin as the major product with anti-stereochemistry and a vic-dihalide as the minor product.

Oxymercuration-Demercuration (Oxyreduction)

A two-step alkene hydration reaction using 1) $Hg(OAc)_2, H_2O$ and 2) $NaBH_4$ that adds across the $\pi$ bond following Markovnikov's rule via a cyclic mercurinium complex without carbocation rearrangement.

Hydroboration-Oxidation of Alkenes

A two-step hydration process using borane ($BH_3$) followed by alkaline peroxide ($H_2O_2, OH^-$) that yields an anti-Markovnikov alcohol without carbocation rearrangement, driven by boron avoiding four bonds.

Monomer

A single small molecule that can chemically combine with itself or other small molecules to form higher-order structures.

Dimer

A chemical species formed by the combination of two monomer units.

Polymer

A large macromolecule composed of many repeating monomer units linked together.

Syn-Dihydroxylation

An oxidation reaction of an alkene using cold $KMnO_4$ or $OsO_4$ that installs two hydroxyl ($-OH$) groups on the same face of the double bond, creating a vicinal diol (vic-diol).

Oxidative Cleavage with Hot $KMnO_4$

A vigorous oxidative cleavage reaction using $KMnO_4$ and heat ($\Delta$) that cleaves double bonds, converting terminal $=CH_2$ into $CO_2$, $=CH-$ into a carboxylic acid ($R-COOH$), and $=C(R)(R')$ into a ketone ($R-CO-R'$).

Ozonolysis (O_3\text{ & }Zn)

An alkene cleavage reaction performed at reduced temperatures using ozone and zinc that converts terminal $=CH_2$ into formaldehyde ($HCHO$), $=CH-$ into an aldehyde ($R-CHO$), and disubstituted carbons into a ketone ($R-CO-R'$).

Catalytic Reduction of Alkenes

The addition of hydrogen gas ($H_2$) in the presence of a metal catalyst ($Pt, Pd, Rh, Ni$) that removes the $\pi$ bond to convert the alkene into an alkane.

Carbene

A divalent, neutral carbon intermediate with two covalent bonds and a lone pair (such as dichlorocarbene, $:CCl_2$) that is highly reactive with almost any molecule.

Halogenation of Alkynes ($\text{Alkyne} + X_2$)

Electrophilic addition of halogens across a triple bond in a non-nucleophilic solvent; addition of $1\,mol$ of $X_2$ yields a vic-dihaloalkene, while $2\,mol$ of $X_2$ yields a tetrahaloalkane with two halogens on each carbon.

Geminal Dihalide (gem-dihalide)

A compound possessing two halogen atoms bonded to the exact same carbon atom, formed by adding $2\,mol$ of $HX$ across an alkyne.

Hydrohalogenation of Alkynes ($\text{Alkyne} + HX$)

An addition reaction following Markovnikov's rule where $1\,mol$ of $HX$ converts an alkyne into a haloalkene, and $2\,mol$ of $HX$ converts it into a gem-dihaloalkane.

Mercury-Catalyzed Hydration of Alkynes

The hydration of an alkyne using $HgSO_4$, $H_2SO_4$, and $H_2O$ that follows Markovnikov's rule without carbocation rearrangement to yield a ketone as the final product.

Hydroboration-Oxidation of Alkynes

A two-step hydration procedure using 1) $BH_3\cdot THF$ and 2) $H_2O_2, NaOH$ that adds water across a terminal alkyne in an anti-Markovnikov fashion without carbocation rearrangement to yield an aldehyde.

Oxidative Cleavage of Alkynes

A cleavage reaction of an alkyne using $KMnO_4$ or ozone ($O_3/HOAc$) that breaks the carbon-carbon triple bond to yield carboxylic acids (carboxylates).

Lindlar's Catalyst Hydrogenation

The metal-catalyzed partial hydrogenation of an alkyne using a poisoned metal catalyst (such as $H_2$ with Lindlar's catalyst or $Ni_2B$) that undergoes syn-addition to selectively produce a cis-alkene.