A new sulfate‐mediated reaction: Conversion of acetone to trimethylbenzene in the presence of liquid sulfuric acid

Abstract

Abstract. A new heterogeneous reaction, namely the sulfate-Unfortunately, virtually all studies of H2SO4-catalyzed and mediated conversion of acetone to 4-methyl-3-penten-2-one and promoted reactions have been carried out under conditions far trimethylbenzene, is reported. The reaction products were observed in their absorbed states by Fourier transform infrared spectroscopy and in the gas phase by mass spectrometry. In addition, protonated, absorbed acetone was observed under certain conditions. The reaction exhibits a strong concentration and / or temperature dependence, with non-reactive uptake as protonated acetone dominating at low temperatures and sulfate concentrations and reactive uptake occurring above 200 K and 75 wt. % H2SO 4. Under conditions where reactive uptake occurs, the steady-state acetone loss probability is roughly 40%.removed from those in the upper troposphere: at room temperature, in concentrated (>96 wt. %) solution, and not via accommodation of the reactants from the gas phase.In this work, we present initial results of a study of the interaction of one tropospherically abundant compound, acetone [(CH3)2CO], with sulfate. The experiments were carried out on ultrathin sulfate films (--100 monolayers thick) of composition between 60 and 96 wt. % H2SO 4 and at temperatures between 180 and 250 K. Infrared spectroscopy and mass spectrometry were used to identify the absorbed and gas-phase reaction It was not possible in this study to assess the relative effects of products, respectively. temperature and concentration on the reactivity of sulfate toward acetone.

Abiotic CC bond formation under environmental conditions: Kinetics of the aldol condensation of acetaldehyde in water catalyzed by carbonate ions (CO3 2− )

“…One of the main objectives of this work is to determine the catalytic contribution of the different bases present in carbonate solutions, CO 3 2− , HCO − 3 , and OH − and to provide expressions to estimate the rate of reaction as a function of acetaldehyde concentrations and other conditions (carbonate ion concentration, and pH). Note that the products of this reaction have been previously identified by 1 H NMR and high-resolution mass spectrometry [8] and will thus not be discussed in the present work.…”

“…Over the past 10 years, the importance of organic bond forming reactions, such as aldol condensation or acetal formation, for the transformation of organic matter in natural environments has started to emerge [1]. In the atmosphere, in particular, these reactions were suggested to contribute to secondary organic aerosols formation [2].…”

Dissolution, speciation, and reaction of acetaldehyde in cold sulfuric acid

“…Simple solubility of known UT/LS organic compounds does not account for the abundance of material seen in situ [ Iraci et al , 2003], but acid‐catalyzed organic reactions could provide an alternate pathway for the incorporation of organic material into particles. Laboratory studies have noted reactions of organic compounds taken up from the gas phase under UT/LS conditions, e.g., polymerization of formaldehyde [ Iraci and Tolbert , 1997] and aldol condensation of acetone [ Duncan et al , 1998; Kane et al , 1999]. The behavior of the acetone/sulfuric acid system is particularly interesting since the reaction has only been observed at high acid compositions (≥75 wt%).…”

Organic reactions increasing the absorption index of atmospheric sulfuric acid aerosols

“…Recent laboratory studies have shown that under atmospheric conditions gas-phase carbonyl compounds are irreversibly taken up by acidic solutions such as sulfuric acid [Duncan et al, 1998[Duncan et al, , 1999Kane et al, 1999;Michelsen et al, 2004; W. Esteve and B. Noziere, Uptake and reaction kinetics of acetone, 2-butanone, and 2,4-pentanedione in sulfuric acid solutions, submitted to Journal of Physical Chemistry, 2004, hereinafter referred to as Esteve and Noziere, submitted manuscript, 2004]. The reaction taking place in the acid has been unambiguously identified as aldol condensation in the case of acetone by identifying the reaction products [Duncan et al, 1998]. As a confirmation, an uptake and kinetic study of acetone, butanone, and 2, 4-pentanedione in sulfuric acid solutions (Esteve and Noziere, submitted manuscript, 2004) shows that the order of reaction, the value of the rates constants, and their variations with acid concentration are in excellent agreement with what predicted for aldol condensation [Baigrie et al, 1985].…”