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Journal of Lipids
Volume 2016, Article ID 3128604, 12 pages
http://dx.doi.org/10.1155/2016/3128604
Research Article

Synthesis of Polyformate Esters of Vegetable Oils: Milkweed, Pennycress, and Soy

1Bio-Oils Research Unit, National Center for Agricultural Utilization Research, United States Department of Agriculture-Agricultural Research Service, 1815 N. University Street, Peoria, IL 61604, USA
2Functional Food Research Unit, National Center for Agricultural Utilization Research, United States Department of Agriculture-Agricultural Research Service, 1815 N. University Street, Peoria, IL 61604, USA

Received 3 June 2015; Accepted 17 December 2015

Academic Editor: Clifford A. Lingwood

Copyright © 2016 Rogers E. Harry-O’kuru et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In a previous study of the characteristics of acyl derivatives of polyhydroxy milkweed oil (PHMWO), it was observed that the densities and viscosities of the respective derivatives decreased with increased chain length of the substituent acyl group. Thus from the polyhydroxy starting material, attenuation in viscosity of the derivatives relative to PHMWO was found in the order: PHMWO ≫ PAcMWE ≫ PBuMWE ≫ PPMWE (2332 : 1733 : 926.2 : 489.4 cSt, resp., at 40°C), where PAcMWE, PBuMWE, and PPMWE were the polyacetyl, polybutyroyl, and polypentanoyl ester derivatives, respectively. In an analogous manner, the densities also decreased as the chain length increased although not as precipitously compared to the viscosity drop. By inference, derivatives of vegetable oils with short chain length substituents on the triglyceride would be attractive in lubricant applications in view of their higher densities and possibly higher viscosity indices. Pursuant to this, we have explored the syntheses of formyl esters of three vegetable oils in order to examine the optimal density, viscosity, and related physical characteristics in relation to their suitability as lubricant candidates. In the absence of ready availability of formic anhydride, we opted to employ the epoxidized vegetable oils as substrates for formyl ester generation using glacial formic acid. The epoxy ring-opening process was smooth but was apparently followed by a simultaneous condensation reaction of the putative α-hydroxy formyl intermediate to yield vicinal diformyl esters from the oxirane. All three polyformyl esters milkweed, soy, and pennycress derivatives exhibited low coefficient of friction and a correspondingly much lower wear scar in the 4-ball antiwear test compared to the longer chain acyl analogues earlier studied.