## 3 Results and Discussion
### Synthesis of Methyl and Decyl Esters
The same main peaks as the ones observed in the spectra of replicated MEPA were observed, namely the singlet at 3.66 ppm from the deshielded methyl group -CH\({}_{3}\) directly attached to the carbonyl group, the triplet at 2.28-2.32 ppm from the -CH\({}_{2}\) in \(\alpha\)-position to the carbonyl, the multiplet from the -CH\({}_{2}\) in \(\beta\)-position at 1.58-1.65 ppm, the peak from the alkane chain around 1.26 ppm and the triplet at 0.86-0.90 ppm from the shielded -CH\({}_{3}\) group at the end of the aliphatic chain. On the other hand, some variances in the spectra for decyl esters allowed differentiation between the diverse groups of esters. Here, a triplet with integral value of 2 instead of a singlet appeared at 4.05-4.07 ppm (a) from the -CH\({}_{2}\) in \(\alpha\)-position to the oxygen of the ester group. This is due to the fact that in 1-decanol, unlike in methanol, the aliphatic chain continues, therefore the -CH\({}_{2}\) in \(\alpha\)-position feels the influence of the neighboring -CH\({}_{2}\). The triplet at 2.28-2.32 ppm (c) from the -CH\({}_{2}\) in \(\alpha\)-position to the carbonyl group remained the same, while the multiplet at 1.58-1.65 ppm (d) from the -CH\({}_{2}\) groups in \(\beta\)-position had an integral equal to 4 hydrogens instead of 2 due to the presence of the additional -CH\({}_{2}\) in \(\beta\)-position to the oxygen from the alcohol side. Similarly, the peak  
Figure 9: ATR-IR spectra of DEPA without purification and with two crystallization in MeOH purifications. A strong increase in the ester peak at 1735 cm\({}^{-1}\) for ester purified twice can be observed, together with the disappearance of the residual Alcohol broad peak at 3100–3600 cm\({}^{-1}\), which verifies the degree of purity of the ester produced and its suitability for further studies. from the alkane chain at 1.26 ppm (e) had an integral value of about 38 hydrogens, and the triplet at 0.86-0.90 ppm (f) corresponded to the 6 hydrogens from the shielded -CH\({}_{3}\) at the end of the aliphatic chains from the acid and the alcohol sides. Small alcohol impurities, when present, were visible in the form of a triplet at 3.62-3.66 ppm (b) from the -CH\({}_{2}\) in \(\alpha\)-position to the hydroxy group of the free alcohol molecules. The ratio between its integral value and the one from the ester signal at 4.05-4.07 ppm allowed to quantify the degree of purity of the sample. As mentioned previously, in the absence of any additional peaks from unreacted reagents, the purity was estimated to be \(\geq\)98%, like in the case of methyl esters. Impurities still present in the decyl esters could also be observed through DSC analysis. In the presence of residual alcohol, a second broad peak appeared between 2-10 \({}^{\circ}\)C (T\({}_{\rm m}\) of 1-Decanol: 6.4 \({}^{\circ}\)C), and lower \(\Delta\)H of about 150-160 J/g were registered. Upon further crystallizations and purifications though, such peak decreased until it was barely visible over the baseline noise of the instrument, and \(\Delta\)H for the ester peak increased again to values over 190 J/g. In general, the results obtained concerning thermal properties of synthesized esters are summarized in Table 1. As mentioned beforehand, the esters names have been abbreviated as follows: methyl myristate (MEMY, C1-14), decoy myristate (DEMY, C10-C14), methyl palmitate (MEPA, C1-C16), decyl palmitate (DEPA, C10-C16), methyl stearate (MESA, C1-C18), decyl stearate (DESA, C10-C18), methyl behenate (MEBE, C1-C22), decyl behenate (DEBE, C10-C22). Figure 10: \({}^{1}\)H NMR spectra of 89% pure DEPA.