In $\text{SOCl}_2$, the sulfur atom makes four bonds. Draw a dot-and-cross diagram of $\text{SOCl}_2$ and display only the outer-shell electrons.
When $\text{SOCl}_2$ reacts with a carboxylic acid to make an acyl chloride, two acidic gases are produced. $\text{SOCl}_2(l) + \text{RCO}_2\text{H}(l) \rightarrow \text{RCOCl}(l) + \text{SO}_2(g) + \text{HCl}(g)$ A $1.00\,\text{g}$ sample of a carboxylic acid $\text{RCO}_2\text{H}$ was treated in this way, and the gases were absorbed in $60.0\,\text{cm}^3$ of $0.500\,\text{mol dm}^{-3}$ $\text{NaOH}(aq)$, which was in excess.
Write equations for the reactions of: $\text{NaOH}$ with $\text{HCl}$, $\text{NaOH}$ with $\text{SO}_2$.
The excess $\text{NaOH}$ was titrated with $0.500\,\text{mol dm}^{-3}$ $\text{H}^+(aq)$. It took $10.8\,\text{cm}^3$ of the $\text{H}^+(aq)$ solution to reach the end-point. Calculate the total number of moles of $\text{NaOH}$ that reacted with the $\text{SO}_2$ and $\text{HCl}$.
Calculate the number of moles of $\text{RCO}_2\text{H}$ that produced the $\text{SO}_2$ and $\text{HCl}$.
Hence calculate the $M_r$ for the carboxylic acid, $\text{RCO}_2\text{H}$.
Since the $\text{R}$ group contains only carbon and hydrogen, suggest the molecular formula of $\text{RCO}_2\text{H}$.
The synthetic route below shows how a carboxylic acid is converted into an amine. $\text{CH}_3\text{CO}_2\text{H} \xrightarrow{\text{SOCl}_2} \text{CH}_3\text{COCl} \xrightarrow{\text{NH}_3} \text{CH}_3\text{CONH}_2 \xrightarrow{\text{step 3}} \text{CH}_3\text{CH}_2\text{NH}_2$
Suggest one reagent for step 3.
Angelic acid, $\text{C}_5\text{H}_8\text{O}_2$, is a natural product isolated from the roots of the angelica plant. Angelic acid reacts with $\text{H}_2 + \text{Ni}$ to form $\text{T}$, $\text{C}_5\text{H}_{10}\text{O}_2$. $\text{T}$ follows the synthetic route above to give the amine $\text{U}$, $\text{C}_5\text{H}_{13}\text{N}$. $\text{U}$ can also be prepared by reacting 1-bromo-2-methylbutane with ammonia. Both angelic acid and $\text{T}$ occur as stereoisomers. Suggest structures for angelic acid, $\text{T}$ and $\text{U}$.
State the type of stereoisomerism for angelic acid and $\text{T}$. Angelic acid: Compound $\text{T}$: