Synthetic Transformations: Halogenation of Alcohols and Synthetic Uses of SN2 Reactions

Vocabulary practice flashcards covering alcohol halogenation using thionyl chloride and phosphorus tribromide, as well as synthetic substitution transformations via SN2 pathways.

Thionyl chloride ($\text{SOCl}_2$)

A reagent used in Synthetic Transformation 13.2 to convert an alcohol ($\text{R-CH}_2\text{-OH}$) into an alkyl chloride ($\text{R-CH}_2\text{-Cl}$), which also requires a mild base that is a poor nucleophile (e.g., pyridine).

Phosphorus tribromide ($\text{PBr}_3$)

A reagent used in Synthetic Transformation 13.3 to convert an alcohol ($\text{R-CH}_2\text{-OH}$) into an alkyl bromide ($\text{R-CH}_2\text{-Br}$), which also requires a mild base that is a poor nucleophile (e.g., pyridine).

Pyridine

A mild base that acts as a poor nucleophile, required in halogenation reactions of alcohols with $\text{SOCl}_2$ or $\text{PBr}_3$ (though not always shown).

Common Leaving Groups ($\text{LG}$)

Leaving groups listed in Synthetic Transformations 13.4a-d that can be displaced in $\text{S}_\text{N}2$ reactions, specifically $\text{Cl}$, $\text{Br}$, $\text{I}$, or $\text{OTs}$.

Synthetic Transformation 13.4b

An $\text{S}_\text{N}2$ transformation that converts an alkyl substrate with a leaving group ($\text{R-CH}_2\text{-LG}$) into an alcohol ($\text{R-CH}_2\text{-OH}$) using $\text{NaOH}$ or $\text{KOH}$.

Sodium Alkoxide Preparation ($\text{NaOR}$)

The formation of a nucleophilic alkoxide reagent generated from sodium metal and alcohol: $2\text{Na}^\circ + 2\text{ROH} \rightarrow 2\text{Na}^+ + 2\text{RO}^- + 1\text{H}_2$.

Synthetic Transformation 13.4c

An $\text{S}_\text{N}2$ substitution in which an alkyl substrate ($\text{R-CH}_2\text{-LG}$) reacts with sodium alkoxide ($\text{NaOR}$) to produce an ether ($\text{R-CH}_2\text{-OR}$).

Synthetic Transformation 13.4d

The deprotonation of a terminal alkyne ($\text{R-C}\equiv\text{C-H}$) using the strong base $\text{NaNH}_2$, followed by an $\text{S}_\text{N}2$ alkylation with $\text{R-CH}_2\text{-LG}$ to form an internal alkyne ($\text{R-C}\equiv\text{C-CH}_2\text{-R}$).