Submitted to: American Oil Chemists' Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2004
Publication Date: 5/12/2004
Citation: Compton, D.L., Laszlo, J.A., Isbell, T. 2004. Sunscreen active ingredients from lesquerella oil. American Oil Chemists' Society Meeting. Interpretive Summary:
Technical Abstract: Lesquerella and castor oil were esterified with cinnamic acid (CA) and 4-methoxycimmic acid (MCA). Esterification of the hydroxy oils reached 85% conversion with CA and 50% conversion with MCA. The hydroxyl oils were esterified at 200°C under a nitrogen atmosphere within a sealed system. Unreacted CA and MCA were removed from the reaction mixtures by sublimation at 100°C under vacuum. The resultant methoxycinnamic-oils possessed a broader, more blue-shifted ultraviolet (UV) absorbance, 250 to 350 nm with a lambda-max of 305 nm, compared to the cinnamic-oils which adsorbed from 260 to 320 nm, lambda-max of 273 nm. The methoxycinnamic-oils provide better UVB adsorption and, thus, are better candidates for sunscreen active ingredients. Esterifications of the hydroxy oils with MCA at 200°C resulted in 40% of the MCA converted to undesirable byproducts. Esterifications with MCA performed at 175°C in the presence of a tin catalyst resulted in similar percent conversions to product without the degradation of MCA. Esterifications of lesquerella oil with MCA resulted in higher conversions, 43%, than analogous esterifications with castor oil, 29%. The hydroxyl groups of the lesquerella and castor provide the oils' excellent emolliency, lubricity, and non-comedogenicity in skin and personal care products. Therefore, reactions that only convert 50% of the available hydroxyl groups of the lesquerella oil to cinnamoyl-esters are preferred.