Volatilization of Various Esters and Salts of 2,4-D

The degree and rate of volatilization, and the partial vapor pressures of the methyl, n butyl, and n octyl esters of 2,4-D [(2,4-dichlorophenoxy)acetic acid] were determined at ambient temperatures using a kinetic system approximating field-air conditions. The initial surface area/applied mass ratio (Q), as well as temperature and the type of compound, determined the volatility. Only when the Q values were kept constant did the volatility decrease with increasing chain length and decreasing saturated vapor pressure as expected. A mathematical model was constructed. Similar results were obtained for the amine salts which had saturated vapor pressures of ca 10−10mm Hg at 38 C. Vapor drift can be essentially eliminated by use of the amine salts.