KINETICS AND MECHANISM OF THE ATMOSPHERIC OXIDATION OF TERTIARY AMYL METHYL-ETHER

Tertiary-amyl methyl ether (TAME) is proposed for use as an additive t o increase the oxygen content of gasoline as stipulated in the 1990 Cl ean Air Amendments. The present experiments have been performed to exa mine the kinetics and mechanisms of the atmospheric removal of TAME. T he kinetics of the reaction of OH with TAME was examined by using a re lative rate technique in which photolysis of methyl nitrite or nitrous acid was used as the source of OH. The OH rate constant for TAME and two major products (t-amyl formate and methyl acetate) were measured a nd yields for ten products were determined as primary products from th e reaction. Values determined for the rate constants for the reaction with OH were 5.48 x 10(-12) (TAME), 1.75 x 10(-12) (t-amyl formate), a nd 3.85 x 10(-13) cm(3) molec(-1) s(-1) (methyl acetate) at 298 +/- 2 K. The primary products (with corrected yields where required) from th e OH + TAME that have been observed include (1) t-amyl formate (0.366) , methyl acetate (0.349), acetaldehyde (0.43, corrected), acetone (0.0 36), formaldehyde (0.549), t-amyl alcohol (0.026), 3-methoxy-3-methyl- butanal (0.044, corrected), t-amyloxy methyl nitrate (0.029), 3-methox y-3-methyl-2-butyl nitrate (0.010), and a-methoxy-a-methyl butyl nitra te (0.004). Mechanisms leading to these products involve OH abstractio n from each of the four different hydrogen atoms of TAME. (C) 1995 Joh n Wiley & Sons, Inc.