# Recent Advances in Muconic Acid Extraction Process
## 4 Muconic Acid Extraction
### Reactive Extraction Systems Used for MA Separation
#### 4.2.1 Reactive Extraction Mechanism  
At the interface between the organic and aqueous phases, the molecules of the extractant (phosphate/aminic groups) and acid (carboxylic group) interact with one another (Figure 3) and result in the development of an acid-extractant complex. The following equations could be used to depict the 1:1, 2:1, or n:1 complex that can result from the complexation reaction between MA and extractant (E), where n is the number of acid molecules, and the subscripts \"aq\" and \"org\" stand for the aqueous and organic phases, respectively: \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Solvent** & **Extractant** & **Extraction Conditions** & **K** & **Ext. Efficiency, \%** & **Ref.** \\ \hline
1-butanol & TBP & 6.83 & 87.013 & [49] \\ isoamyl alcohol & TBP & 5 mL equal volumes at both aqueous and & 3.18 & 75.546 & [49] \\ methyl ethyl ketone & TBP & organic phases & 2.73 & 70.897 & [49] \\ methyl isobutyl ketone & TBP & 120 rpm for two hours in a & 5.17 & 82.524 & [49] \\ di-isobutyl ketone & TBP & temperature-controlled water bath shaker & 3.54 & 74.438 & [49] \\ Iso-butanol & TBP & Initial acid concentration: & 6.49 & 85.979 & [49] \\ n-hexane & TBP & 0.0008–0.00215 mol/kg & 5.86 & 83.293 & [49] \\ dimethyl glutamate & TBP & Extractant concentration & 6.56 & 86.161 & [49] \\ ethyl propionate & TBP & 0.47–2.06 mol/kg & 6.32 & 85.214 & [49] \\ diethyl carbonate & TBP & 5.33 & 83.017 & [49] \\
1-butanol & TOPO & 5.51 & 84.627 & [49] \\ isoamyl alcohol & TOPO & 5 mL equal volumes at both aqueous and & 5.26 & 83.305 & [49] \\ methyl ethyl ketone & TOPO & organic phases & 2.82 & 72.887 & [49] \\ methyl isobutyl ketone & TOPO & 120 rpm for two hours in a & 4.83 & 81.929 & [49] \\ di-isobutyl ketone & TOPO & temperature-controlled water bath shaker & 4.07 & 78.522 & [49] \\ iso-butanol & TOPO & Initial acid concentration: & 3.93 & 79.629 & [49] \\ n-hexane & TOPO & 11.26 & 91.351 & [49] \\ dimethyl glutamate & TOPO & Extractant concentration & 0.135–0.756 mol/kg & 7.53 & 87.457 & [49] \\ ethyl propionate & TOPO & 7.78 & 88.126 & [49] \\ diethyl carbonate & TOPO & 5.49 & 83.795 & [49] \\  & & 20\% (\varepsilon/\gamma) solvent & & \\ canola oil & CYTOP 503 & 900 rpm mixing & 8.70 & - & [51] \\  & Time: 30 min T: 30 \({}^{\circ}\)C & & \\ sunflower FAME & CYTOP 503 & aqueous phase pH: 4.25 & 9.28 & - & [51] \\ canola oil & CYPOS IL-101 & Extractant ratio [\% \(\gamma/\gamma\)]: & 51.33 & - & [51] \\ sunflower FAME & CYPOS IL-101 & 25 CYTOPO 503; 12.5 CYHOS IL-101 & 27.62 & - & [51] \\ ethyl oleate & di-hexylamine, & Total working volume of & - & 92.02 & [52] \\  & DHA & 60 mL, and a phase ratio of 1:2 aqueous to & & \\ ethyl oleate & tri-n-hexylamine, & organic in a 100 mL double-walled & - & 76.07 & [52] \\  & THA & glass reactor & & \\ ethyl oleate & tri-n-octylamine, & phase ratio of 12 (\(m_{\mathrm{aq}}\):\(m_{\mathrm{org}}\)) & - & 94.08 & [52] \\ ethyl oleate & di-n-octylamine, & 1000 rpm mixing & - & 96.13 & [52] \\  & DOA & MA concentration 0.035 mol/kg & & \\  & & extractant concentration: 0.015 mol/kg & & \\  & & phase ratio of 12 (\(m_{\mathrm{aq}}\):\(m_{\mathrm{org}}\)) & & \\ ethyl oleate + & di-n-octylamine, & 1000 rpm mixing & & \\
1-dodecanol & DOA. & MA concentration 0.035 mol/kg & - & 98.66 & [52] \\  & & extractant concentration: 0.1 mol/kg & & \\  & & 1-dodecanol weight fraction 0.3 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Muconic acid reactive extraction system [49; 50; 51; 52]. \(\text{MA}_{\text{aq}}\) + [E]\({}_{\text{org}}\)\(\rightarrow\) [MA:E]\({}_{\text{org}}\),  
\(\text{MA}_{\text{aq}}\) + [MA:E]\({}_{\text{org}}\) \(\rightarrow\) [(MA)\({}_{2}\): E]\({}_{\text{org}}\),  
\(\text{MA}_{\text{aq}}\) + [MA\({}_{\text{n-1}}\):E]\({}_{\text{org}}\)\(\rightarrow\) [MA\({}_{\text{n-1}}\):E]\({}_{\text{org}}\). For MA, [PERSON] et al. (2021) [49] and [PERSON] et al.