1 research outputs found
Correlation Method for Conversion Determination of Biodiesel Obtained from Different Alcohols by <sup>1</sup>H NMR Spectroscopy
This
work presents a correlation method that uses <sup>1</sup>H
NMR spectra for determining the conversion during transesterification
of vegetable oil with 10 alcohols: methanol, ethanol, 1-propanol,
2-propanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, isopentanol,
1-hexanol, 1-heptanol, 1-octanol, 1-decanol, 1-dodecanol, and benzyl
alcohol. Conversions ranging from 70 to 99%, depending on primary
alcohol used, are obtained using organic catalyst <i>N</i>,<i>N</i>′,<i>N</i>″-tris(3-(dimethylamino)propyl)guanidine.
Catalysts, alcohols, and intermediate products can cause signal overlapping,
debilitating the use of the conventional <sup>1</sup>H NMR method.
Thus, our method uses the correlation between the triplet signal of
α-carbonylmethylene and two signals of unsaturated parts of
the fatty acid chain, where signal overlapping does not occur, hence,
adding robustness and flexibility to the method. The method is applicable
for unsaturated oils and is not affected by the amounts of residual
alcohol, catalyst, or intermediate products, making it ideal for conversion
determination and <i>in situ</i> monitoring of complex mixtures.
In addition, we present a systematic analysis of the <sup>1</sup>H
NMR spectra of biodiesels produced with the mentioned alcohols