The intrinsic reaction rates for anhydrous vapor-phase HF saccharification of celluloslc materials in Bigtooth aspen were determined in order to characterize and assess this process for the production of fermentable sugars. Maximum glucose yields of 3.0 mmol/g of wood were recovered from wood chips reacted for 2 min with a pure HF flowstream at 30 °C and 1.0 atm. The intrinsic glucose yield vs. time profile was sigmoidal. The glucose production rate decreased nonHnearfy with decreasing HF partial pressure from 1.0 to 0.2 atm at 30 °C. Surprisingly, the glucose production rate decreased with increasing reaction temperature from 28 to 108 °C at an HF partial pressure of 1.0 atm. It is proposed that physical adsorption of HF onto the lignocellulosic matrix and hydrogen-bond breaking of cellulose microfibrils are prerequisites to the cellulose-cracking reaction and therefore may strongly influence the global rate of glucose production.

Castor oil and Its polyol derivatives have been used as a matrix to prepare controlled-release (2,4-dichlorophenoxy)acetlc acid (2,4-D) formulations, and their release characteristics have been studied both in vivo and in vitro. The initial release rate has been found to be dependent on the hydrophllicity of the formulations. The pH of the hydrolysis also strongly affects the release characteristics; the release rate Increases sharply in the alkaline range (pH 10). Cross-linking via carbamate linkage has been found to retard the release rate. Compared to formulations based on natural or synthetic polymer matrices, such castor oil-based preparations are likely to be more suitable for agricultural applications requiring shorter release period of the toxicant.