A kinetic study of the reactions of NO3 with methyl vinyl ketone, methacrolein, acrolein, methyl acrylate and methyl methacrylate

Absolute and relative-rate techniques have been used to obtain rate coefficients for the reactions: NO3+CH3C(O)CHCH2--> products (1), NO3+CH2C(CH3)CHO --> products (2), NO3+CH2CHCHO --> products (3), and NO3+CH2CHC(O)OCH3--> products (4). The reaction NO3+CH2C(CH3)C(O)OCH3--> products (5), has been investigated by a relative-rate method only. The rate coefficients obtained by the relative-rate method at T=296 +/- 2 K and P=760 Torr are k(1)=(4.7 +/- 1.7)x10(-16) cm(3) molecule(-1) s(-1), k(2)=(3.7 +/- 1.0)x10(-15) cm(3) molecule(-1) s(-1), k(3)=(1.1 +/- 0.4)x10(-15) cm(3) molecule(-1) s(-1), k(4)=(1.0 +/- 0.6)x10(-16) cm(3) molecule(-1) s(-1) and k(5)=(3.6 +/- 1.3)x10(-15) cm(3) molecule(-1) s(-1). The rate coefficients determined by the discharge-flow technique at low pressure (P=1-10 Torr) and at T=293-303 K are k(1)=(3.2 +/- 0.6)x10(-16) cm(3) molecule(-1) s(-1), k(2)=(9.6 +/- 2.0)x10(-15) cm(3) molecule(-1) s(-1), k(3)=(8.9 +/- 2.8)x10(-15) cm(3) molecule(-1) s(-1), k(4)=(1.9 +/- 0.4)x10(-16) cm(3) molecule(-1) s(-1). The discrepancy between the values obtained from the relative-rate technique and the absolute technique are discussed and explained in terms of interference in the absolute study caused by secondary chemistry and fast-reacting impurities. Product studies reveal that methyl glyoxal is a product of reactions (1) and (2) along with peroxymethacryloyl nitrate (MPAN) for reaction (2) in air. A diurnally varying boundary-layer model suggests that reaction (2) is an important loss process for methacrolein and that it can lead to the generation of OH at night.