The Thermal Degradation of Tobacco: VI. Influence of Extraction on the Formation of Some Major Gas Phase Constituents

Abstract

Formation profiles have been determined for the major gas phase constituents formed in an inert atmosphere during the dynamic thermal decomposition of tobaccos extracted with hexane, chloroform, acetone, acetonitrile, and methanol. The profiles include methane, ethane, ethene, propane, propene, isoprene, formaldehyde, acetaldehyde, acetone, 2-butanone, acetonitrile, benzene, and toluene. Except for propene and propane, extraction of tobacco does not dramatically influence either the temperatures for maximum formation or the level of hydrocarbons formed during thermal decomposition of the tobaccos. This suggests that the majority of the gas phase hydrocarbons are formed from the insoluble leaf constituents. Isoprene has formation maxima at 375°C and 450°C, and extraction of tobacco with non-polar solvents removes leaf precursors responsible for the formation maxima at 375°C. Polar solvents remove the major isoprene precursors which are responsible for the maxima at 375° and 450°C. Extraction effects an increase of both formaldehyde and acetaldehyde formation but has little influence on the formation of either acetone or 2-butanone. The formation profile for acetonitrile has been established and shows that it has maximum formation at 410° and 500°C. Extraction has no influence either on the formation of benzene or toluene. Data from the profiles of these volatile constituents generally agree with smoke data from extracted tobacco which indicates that this method is useful for studying factors that influence the formation of the gas phase constituents

Carbohydrate pyrolysis mechanisms from isotopic labeling

“…Acrolein (propenal) (5). The isotopic scrambling experiment showed that 90% of the acrolein derived from Dglucose pyrolysis arose in unimolecular fashion.…”

Carbohydrate pyrolysis mechanisms from isotopic labeling

“…Upon cooling and condensation, enol-acetaldehyde 6 reverts to the carbonyl tautomer 4, which is the observed product under our conditions (Scheme 2). By this unimolecular mechanism, C-2 of glycerin specifically ends up as the aldehyde carbon of acetaldehyde (4). The Cyclic Grob Fragmentation would be expected to be available for operation in either the gas phase or a condensed phase.…”

“…Such chemistry is also relevant to the formation of cigarette smoke [4]. The mechanisms involved in this chemistry are therefore of considerable importance to understand.…”

Carbohydrate pyrolysis mechanisms from isotopic labeling

“…Carbohydrate pyrolysis is of central importance in the thermochemical conversion of biomass to sources of energy [1][2][3], the formation of flavors during the cooking of food [4], and in the formation of cigarette smoke constituents generated from carbohydrates in tobacco by the act of smoking [5,6]. Yet despite this importance, much of the detailed chemistry remains poorly understood, and the pathways of product formation of numerous pyrolysis products remain debatable [7].…”