Hydroxylation of sunflower, corn and crambe oils and chemical characterization of the obtained vegetable polyols

ABSTRACT

In this work, vegetable polyols were synthesized and characterization from sunflower’s, corn’s and crambe’s oils. The polyols were obtained from the chemical modification of the vegetable oils by the direct hydroxylation reaction with the peracid system in situ (formic acid and hydrogen peroxide) in the molar ratio (oil/acid/peroxide) of 1,0:3.0:1,5, temperature of 85 ºC, reaction time of 6 h with mechanical agitation. The products were characterized by viscosity, density, infrared spectroscopy (FTIR), hydroxyl number (IOH), iodine value (II) and acidity level (IA). The polyol with the best properties was obtained from sunflower oil, with IOH of 72.88 mg KOH/g of sample, II of 11.87 g I₂/g sample, IA of 16.13 mg of NaOH/g sample and viscosity of 1096.4 mPa.s. The crambe polyol presented IOH of 40.80 mg KOH/g of sample, II of 78.18 g of I₂/g sample, IA of 4.25 mg of NaOH/g of sample and viscosity of 649.9 mPa.s. Finally, the corn polyol presented IOH of 37.40 mg of KOH/g of sample, II of 62.47 g of I₂/g of sample, IA of 54.62 mg of NaOH/g of sample and viscosity of 486.8 mPa.s. The application of the FTIR technique in the obtained polyols allowed the qualitative analysis of the hydroxyl groups by the appearance of a wide band in the range of 3400-3500cm^-1, characteristic of this functional group. It was possible to synthesize the vegetable polyols from the hydroxylation reaction of the studied oils and the products have potential to be used in the synthesis of flexible polyurethanes, increasing the added value of the raw materials studied.

Keywords
Oilchemistry; vegetable polyols; hydroxylation