Decarboxylation & Hunsdiecker Core Degradation

$$\begin{aligned} \text{Soda Lime Decarboxylation:} &\quad \text{R-COONa} + \text{NaOH} \xrightarrow{\text{CaO}, \, \Delta} \text{R-H} + \text{Na}_2\text{CO}_3 \\ \text{Hunsdiecker Degradation:} &\quad \text{R-COOAg} + \text{Br}_2 \xrightarrow{\text{CCl}_4, \, \Delta} \text{R-Br} + \text{CO}_2(g) \uparrow + \text{AgBr} \downarrow \end{aligned}$$

Concept: Carbon chain degradation methods that break carbon-carbon single bonds to extrude carbon dioxide gas. The soda lime technique routes through a carbanion intermediate, while the Hunsdiecker pathway runs via a free-radical mechanism to transform a silver salt into a regular alkyl halide.

Notation:

• $$\text{CaO}$$ = Quicklime keeping the reaction system dry; Decreases the total parent carbon chain length by exactly one carbon atom.