Alkene and Alkyne Addition Reactions Cheat Sheet

Comprehensive vocabulary flashcards covering the mechanism characteristics, reagents, stereochemistry, and regiochemistry of alkene and alkyne addition reactions.

Hydrohalogenation of Alkenes

An electrophilic addition reaction using $HX$ ($X = Cl, Br, \text{or } I$) that yields an alkyl halide with Markovnikov regioselectivity and no stereochemical preference, proceeding through a carbocation intermediate where rearrangement can occur.

Modified Hydrobromination of Alkenes

A radical addition reaction using $HBr$ and $ROOR$ (peroxides) yielding an alkyl halide with anti-Markovnikov regioselectivity and no stereochemical preference; it does not form a carbocation intermediate and only works with $Br$.

Acid-Catalyzed Hydration of Alkenes

The addition of water using $H_3O^+$ across a double bond to form an alcohol with Markovnikov regioselectivity and no stereochemical preference, proceeding via a carbocation intermediate that may undergo rearrangement.

Acid-Catalyzed Ether Formation

The reaction of an alkene with an alcohol in the presence of an acid catalyst ($HOR, H^+$) to produce an ether with Markovnikov regioselectivity and no stereochemical preference; it involves a carbocation intermediate that can rearrange.

Oxymercuration-Demercuration

A two-step addition using 1. $Hg(OAc)_2, H_2O$ and 2. $NaBH_4$ that produces a Markovnikov alcohol with no stereochemical preference without forming a carbocation intermediate or undergoing rearrangement.

Modified Oxymercuration-Demercuration

A two-step addition using 1. $Hg(OAc)_2, HOR$ and 2. $NaBH_4$ that produces a Markovnikov ether with no stereochemical preference without forming a carbocation intermediate or undergoing rearrangement.

Halogenation of Alkenes

The addition of molecular halogen $X_2$ ($X = Br \text{ or } Cl$) across an alkene in a non-participating solvent such as $CCl_4$ or $CH_2Cl_2$, proceeding with Markovnikov regioselectivity and anti stereoselectivity to yield a vicinal dihalide.

Halohydrin Formation

The reaction of an alkene with $X_2$ ($X = Br \text{ or } Cl$) and $H_2O$ with anti stereoselectivity and Markovnikov regioselectivity, wherein the alcohol ($-OH$) group selectively adds to the more substituted Markovnikov position.

Haloether Formation

The reaction of an alkene with $X_2$ ($X = Br \text{ or } Cl$) and an alcohol ($HOR$) with anti stereoselectivity and Markovnikov regioselectivity, wherein the ether ($-OR$) group adds to the more substituted Markovnikov position.

Hydroboration-Oxidation of Alkenes

A two-step hydration process using 1. $BH_3, THF$ (or $R_2BH$, 9-BBN) and 2. $H_2O_2, HO^-$ to synthesize an alcohol with anti-Markovnikov regioselectivity and syn stereoselectivity.

Syn Dihydroxylation

The addition of two hydroxyl groups across a double bond to form a syn diol using 1. $OsO_4, pyr$ followed by 2. $NaHSO_3, H_2O$, with alternative recipes including $OsO_4, NMO$, $OsO_4, tBuOOH$, or cold $KMnO_4, NaOH$.

Epoxide Formation via Peroxyacid

The stereospecific syn oxidation of an alkene directly into an epoxide using a peroxyacid such as $RCO_3H$ or $mCPBA$.

Epoxide Formation via Halohydrin

A two-step pathway yielding an epoxide with overall syn stereoselectivity by treating an alkene with 1. $X_2, H_2O$ to form a halohydrin, followed by 2. $NaOH$ (or any strong base) to induce intramolecular ring closure.

Anti Dihydroxylation

A two-step conversion yielding a trans diol with anti stereoselectivity, where step 1 uses $RCO_3H$ to form an epoxide, and step 2 uses $H_3O^+$ to perform acid-catalyzed ring opening.

Catalytic Hydrogenation of Alkenes

The syn addition of $H_2$ across an alkene to yield an alkane catalyzed by $Pt$ (which can be substituted with $Ni$, $Pd$, or $Pd/C$); this catalyst system will not reduce $C=C$ bonds in an arene.

Ozonolysis of Alkenes

The oxidative cleavage of a double bond using 1. $O_3$ and 2. $Zn, H^+$ or $(CH_3)_2S$, where carbon atoms with 0 attached hydrogens yield ketones, 1 attached hydrogen yields aldehydes, and 2 attached hydrogens yield formaldehyde.

Hydrohalogenation of Alkynes

The sequential addition of 1 equivalent of $HX$ followed by a second equivalent of $HX$ ($X = Br, Cl, \text{or } I$) across an alkyne with Markovnikov regioselectivity and no stereochemical preference, converting the alkyne to a geminal dihalide.

Modified Hydrobromination of Alkynes

The addition of 1 equivalent of $HBr, ROOR$ followed by a second equivalent to an alkyne with anti-Markovnikov regioselectivity and no stereochemical preference; it only occurs with $Br$, and the intermediate vinyl halide is formed as a mixture of $E/Z$ isomers.

Halogenation of Alkynes

The stepwise addition of 1 equivalent of $X_2$ followed by a second equivalent ($X = Br \text{ or } Cl$) with Markovnikov regioselectivity and anti addition, initially yielding a trans dihalide alkene before completing addition.

Acid-Catalyzed Hydration of Alkynes

The Markovnikov addition of water across an alkyne using $H_2O, H_2SO_4$ and an $HgSO_4$ catalyst (necessary for terminal alkynes, but usable on internal alkynes), forming an enol intermediate that undergoes tautomerization to yield a ketone.

Hydroboration-Oxidation of Alkynes

An anti-Markovnikov addition of water across an alkyne using 1. $R_2BH, THF$ (using bulky boranes like 9-BBN or disiamylborane, avoiding $BH_3$ for terminal alkynes) and 2. $HO^-, H_2O_2$, forming an enol that tautomerizes to an aldehyde.

Catalytic Hydrogenation of Alkynes

The complete syn reduction of an alkyne to an alkane using excess $H_2$ over transition metal catalysts such as $Pt$, $Ni$, $Pd$, or $Pd/C$.

Poisoned Catalytic Hydrogenation

The stereoselective syn hydrogenation of an alkyne using $H_2$ over Lindlar's catalyst, which arrests reduction at the intermediate stage to selectively produce a cis alkene.

Dissolving Metal Reduction

The anti reduction of an internal alkyne to produce a trans alkene using sodium or lithium in liquid ammonia ($Na \text{ or } Li, NH_3$) at $-78^\times C$; this reaction is avoided on terminal alkynes.

Ozonolysis of Alkynes

The oxidative cleavage of an alkyne using 1. $O_3$ and 2. $H_2O$ that cleaves the triple bond to produce carboxylic acids and releases $CO_2$ from the terminal alkyne carbon.

Alkyne Chain Extension

A two-step alkylation sequence involving deprotonation of a terminal alkyne with strong base $NaNH_2$ in $NH_3$ at $-78^\times C$, followed by nucleophilic substitution on a primary ($1^\times$) alkyl halide ($R\text{-}Br$).