Molecular inclusion of butylated hydroxyanisole (BHA) into alpha and beta cyclodextrins

BHA (butylated hydroxyanisole) was complexed with ??- and ??-cyclodextrins with the objective of characterizing the thermal stability. From phase solubility diagrams, the association constants for the complexes of ??-CD:BHA and ??-CD:BHA were found as 49.3 and 585 L mol^?1, respectively. To increase the thermal stability of BHA, its molecular encapsulation in ??-CD and ??-CD, was tested using molar ratios of 1:1 and 1:2 (BHA:CD) and the complex preparation techniques of kneading and physical mixture. The products of complexation were characterized by differential scanning calorimetry and thermogravimetry, indicating the formation of a BHA:??-CD complex and showing that the release of the complexed BHA occurs in the temperature range of 280?C350 °C, well above the temperature at which BHA sublimates. Dissolution tests have shown that the BHA: ??-CD complex produced by kneading has high efficiency of dissolution and partition coefficient experiments demonstrated that the presence of ??-CD leads to higher concentration of BHA in the organic phase.