## 3 Results
### Gc-Ms  
While the ATR-IR could prove the formation of the ester group and the purity of the samples produced, it could not directly allow to quantify the purities and to identify the structure of the ester analyzed. As such, GC-MS and NMR were used for this purpose. Table 1 shows the retention times retrieved and the main fragmentation peaks observed in GC-MS. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Compound** & **Retention Time GC, min** & **Fragmentation Peaks MS, _m/z_ with Relative Intensities (\%)** \\ \hline \multirow{2}{*}{**PEMY**} & \multirow{2}{*}{16.53} & 298 (4), 255 (2), 229 (4), 211 (22), 199 (4), 185 (9), 171 (3), 157 (2), 143 \\  & & (9), 129 (11), 115 (9), 97 (8), 83 (9), 70 (100), 57 (22) \\ \hline \multirow{2}{*}{**PEPA**} & \multirow{2}{*}{18.26} & 326 (7), 284 (1), 257 (42), 239 (16), 227 (3), 213 (6), 199 (5), 185 (5), 171 (4), 157 (6), 143 (7), 129 (9), 115 (11), 97 (9), 83 (10), 70 (100), 57 (22) \\ \hline \multirow{2}{*}{**PESA**} & \multirow{2}{*}{19.86} & 354 (7), 311 (1), 285 (30), 267 (10), 241 (7), 227 (1), 213 (1), 199 (4), 185 (5), 171 (1), 143 (7), 129 (11), 115 (10), 97 (8), 83 (11), 70 (100), 57 (28) \\ \hline \multirow{2}{*}{**PEBE**} & \multirow{2}{*}{22.70} & 411 (12), 341 (29), 323 (7), 297 (4), 281 (1), 255 (2), 241 (3), 227 (1), 207 (8), 199 (4), 185 (5), 143 (8), 131 (9), 115 (10), 97 (10), 83 (10), 70 (100), 57 (30) \\ \hline \multirow{2}{*}{**MEAR**} & \multirow{2}{*}{18.64} & 326 (19), 295 (5), 283 (14), 269 (3), 255 (4), 241 (7), 227 (7), 213 (4), 199 (7), 185 (8), 171 (5), 157 (4), 143 (22), 129 (9), 115 (5), 101 (8), 87 (71), 74 (100), 57 (19) \\ \hline \multirow{2}{*}{**PEAR**} & \multirow{2}{*}{21.33} & 382 (14), 340 (1), 313 (34), 295 (12), 283 (1), 269 (8), 255 (1), 241 (2), 227 (2), 213 (4), 213 (4), 199 (6), 185 (4), 171 (3), 157 (2), 143 (6), 129 (10), 115 (11), 97 (10), 83 (11), 70 (100), 57 (33) \\ \hline \multirow{2}{*}{**DEAR**} & \multirow{2}{*}{24.52} & 453 (8), 341 (1), 327 (3), 313 (50), 295 (4), 281 (6), 269 (5), 253 (4), 227 (1), 207 (23), 185 (6), 171 (1), 157 (1), 140 (57), 129 (7), 115 (3), 111 (35), 97 (34), 85 (36), 69 (40), 57 (100) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Retention times in min derived from the gas chromatography (GC) chromatograms measured and fragmentation patterns reported from mass spectroscopy (MS) spectra with relative intensities in brackets. The most abundant fragment is assigned a value of 100% while all other fragments’ intensities are calculated as a relative percentage of the main fragment. Figure 1: Attenuated total reflectance infrared spectroscopy (ATR-IR) of methyl, pentyl and decyl esters synthesized in this study compared to commercial methyl palmit (indicated ad Sigma). The appearance of the peaks at 1750 and 1150 cm\({}^{-1}\) from the stretching of C=O and C-O-C in esters confirm the formation of the ester group. Impurities from unreacted alcohol or carboxylic acid would be visible at 3600–3100 and 3000–2100 cm\({}^{-1}\) from the stretching of free O-H in alcohols and carboxylic acids respectively, and at 1705 cm\({}^{-1}\) from the C=O stretching of carboxylic acids. Concerning GC analysis, no additional peaks beside the ester one were visible in the chromatogram, thus denoting the high purity of the compounds synthesized. Moreover, as expected, the retention times could be seen to increase for increasing carbon chain length due to higher apolarity, and consequently longer retention of the sample in the column. In MS spectra the molecular peak could be observed for all samples with low relative intensity for pentyl and decyl esters (\(\leq\)15%), and higher for MEAR (\(\sim\)20%). The loss of the alkyl alcohol carbon chain and formation of an enolate ion from the molecular ion was visible for pentyl and decyl esters with high abundances (\(\geq\)29%). This corresponded to losses of 70 \(m/z\) and 140 \(m/z\) for pentyl and decyl esters respectively. In addition, all pentyl esters showed a peak deriving from the loss of 87 \(m/z\) corresponding to the loss of 1-pentanol.