Organic Chemistry Reagents and Mechanisms

Flashcards covering chemical reagents, reaction conditions, and mechanisms for transformations involving alkanes, alkenes, alkynes, and alcohols.

$\text{HCl}$ at $25\,^\circ\text{C}$

Converts a tertiary alcohol to an alkyl halide using an $\text{S}_\text{N}1$ mechanism; it never involves a primary carbocation.

$\text{Cl}_2$ and $hv$

Converts an alkane to an alkyl halide via free radical substitution; requires heat or light and is not regioselective.

$\text{Br}_2$, $hv$, and heat

Converts an alkane to an alkyl halide via free radical substitution; regioselective for tertiary carbons and requires both heat and light.

$\text{SOCl}_2$ and pyridine

Converts a primary or secondary alcohol to an alkyl halide via an $\text{S}_\text{N}2$ mechanism.

$$\text{PBr}_3$$

Converts a primary or secondary alcohol to an alkyl halide via an $\text{S}_\text{N}2$ mechanism.

$\text{conc. H}_2\text{SO}_4$ and heat

Converts an alcohol to an alkene via an $\text{E}1$ mechanism; may involve carbocation rearrangement.

$\text{KOCH(CH}_3)_3$, $\text{HOC(CH}_3)_3$, and heat

Converts an alkyl halide to an alkene; the halogen and hydrogen must be anti; involves a "grab slam boot" mechanism.

$\text{H}_2$ and $\text{Pd}$

Converts an alkene to an alkane by adding hydrogen to either side of a double bond.

$\text{HCl}$ at $0\,^\circ\text{C}$

Converts an alkene to an alkyl halide via electrophilic addition; follows Markovnikov addition of the halogen and allows carbocation rearrangement.

$\text{H}_2\text{SO}_4$ and $\text{H}_2\text{O}$

Converts an alkene to an alcohol via electrophilic addition; follows Markovnikov addition of the $\text{OH}$ group and may involve carbocation rearrangement.

$\text{HBr}$ at $0\,^\circ\text{C}$

Converts an alkene to an alkyl halide via electrophilic addition; follows Markovnikov addition of $\text{Br}$ and allows carbocation rearrangement.

$\text{HBr}$ with peroxides or $hv$

Converts an alkene to an alkyl halide via free radical addition; follows anti-Markovnikov addition of $\text{Br}$.

Hydroboration-Oxidation ($1.\,\text{BH}_3\text{-THF}$, $2.\,\text{H}_2\text{O}_2$ $\text{NaOH}$)

Converts an alkene to an alcohol; results in anti-Markovnikov addition of $\text{OH}$ and syn addition of $\text{OH}$ and $\text{H}$.

$\text{Cl}_2$ or $\text{Br}_2$ (dark and cold)

Converts an alkene to a vicinal dihalide via electrophilic addition; if the alkene is disubstituted and E, it becomes a meso compound.

$\text{Cl}_2$ or $\text{Br}_2$ and $\text{H}_2\text{O}$

Converts an alkene to a vicinal halohydrin; the halide adds to the less substituted carbon via anti addition.

Peroxyacetic acid

Converts an alkene to an epoxide; cis configuration stays cis and trans stays trans.

Ozonolysis ($1.\,\text{O}_3$, $2.\,\text{H}_2\text{O}/\text{Zn}$ or $1.\,\text{O}_3$, $2.\,\text{HOCH}_3(\text{CH}_3)_2\text{S}$)

Converts an alkene into carbonyl products; described as "slice slide slam an oxygen."

Oxidative Ozonolysis ($1.\,\text{O}_3$, $2.\,\text{H}_2\text{O}$)

Converts an alkene into carbonyl products; slices the double bond to add oxygen and converts hydrogens on the double bond to hydroxyl groups.

$\text{KOCH}_2\text{CH}_3$ and $\text{HOCH}_2\text{CH}_3$

Nucleophilic substitution where the nucleus replaces the leaving group (usually a halogen) via backside attack, inverting the orientation.

$\text{NaNH}_2$ and $\text{NH}_3$

Converts a terminal alkyne to an acetylide anion which can be used in subsequent $\text{S}_\text{N}2$ reactions.

Alkyne Formation ($1.\,3\text{NaNH}_2, \text{NH}_3$, $2.\,\text{H}_2\text{O}$)

Converts a vicinal dihalide to an alkyne via a double $\text{E}2$ reaction ($2\text{NH}_3$), followed by deprotonation ($\text{NH}_3$) and acid workup ($\text{H}_2\text{O}$).

$\text{H}_2$ and Lindlar catalyst

Converts an alkyne to a cis alkene via syn addition of two hydrogens; prevents the reaction from going all the way to an alkane.

$\text{Na}$ and $\text{NH}_3$

Converts an alkyne to a trans alkene.

$\text{H}_2\text{SO}_4$ and $\text{HgSO}_4$

Converts an alkyne to a ketone; alcohol is added to the terminal or Markovnikov carbon; mercury takes pi bond electrons to form a double bond.

Chromic Acid ($\text{Na}_2\text{Cr}_2\text{O}_7$, $\text{H}_2\text{O}$, $\text{H}_2\text{SO}_4$, heat)

Oxidizes a primary alcohol to a carboxylic acid and a secondary alcohol to a ketone.

$\text{PCC}, \text{CH}_2\text{Cl}_2$ or $\text{PDC}, \text{CH}_2\text{Cl}_2$

Oxidizes a primary alcohol to an aldehyde (stops at the aldehyde) and a secondary alcohol to a ketone.

$$\text{Mg}$$

Adds Magnesium to an alkyl halide ($\text{R-X}$) to create Grignard reagents.

$$\text{OsO}_4$$

Converts an alkene to a diol via syn addition of hydroxyl groups.

$$\text{HIO}_4$$

Converts an adjacent diol to two ketones; it splits the bond between the alcohols and converts the $\text{C-OH}$ bond to a $\text{C=O}$ bond.

$$\text{LiAlH}_4$$

Reduces all carbonyl groups by removing the oxygen double bond and giving the oxygen a charge; requires an acid workup to create a stable oxygen.

$$\text{NaBH}_4$$

Reduces aldehydes and ketones by removing the oxygen double bond and giving the oxygen a charge; requires an acid workup for a stable oxygen.

Ethylene oxide

The simplest epoxide; reacts easily to add $\text{-OCH}<em>2 ext{CH}_2$; useful for creating primary alcohols on terminals via Grignard or $\text{S}</em>\text{N}2$ reactions.