Polycyclic Aromatic Hydrocarbons and Azaaromatic Compounds

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are moderately reactive, but undergo photochemical degradation in the atmosphere, and are widely used as chemical raw materials. Aromatic hydrocarbons cause local irritation and changes in endothelial cell permeability and are absorbed rapidly. Accumulation of aromatic hydrocarbons in marine animals occurs to a greater extent and retention is longer compared to alkanes. Toxicity of polynuclear aromatics has been reported comprehensively. It has been reported that exposure to a variety of complex mixtures containing these chemicals, such as soot, coal tar and pitch, mineral oils, coal gasification residues, and cigarette smoke has historically been associated with induction of cancer. Naphthalene causes cataracts in the eyes of experimental animals. Its vapors may cause severe systemic injury. Alkylbenzenes are readily aspirated and produce instant death via cardiac arrest and respiratory paralysis. In general, the acute toxicity of alkylbenzenes is higher for toluene than that for benzene and decreases further with increasing chain length of the substituent, except for highly branched C 8 to C 18 derivatives. Polycyclic aromatic hydrocarbons are metabolized through epoxides and hydroxides and are excreted as conjugates.

Benzo[a]pyrene: Standard Thermodynamic Properties from Adiabatic and Combustion Calorimetry and Density Functional Theory

“… a Standard uncertainty u is u ( p ) = 10 kPa (0.95 level of confidence); m (sample), m (paraffin), and m (cotton) are masses of the sample (ρ = 1.351 g·cm –3 ), paraffin wax (ρ = 0.900 g·cm –3 ), and cotton thread (ρ = 1.500 g·cm –3 ), respectively, in vacuum; standard uncertainty is u ( m ) = 0.00002 and u (ρ) = 0.002 g·cm –3 ; m (soot) is the mass of the soot formed in the experiment; p (O 2 ) is the initial pressure of oxygen in the bomb; T i and T f are the initial and final temperatures in the main period, respectively, Δ T c is the corrected temperature rise; standard uncertainty u is u (Δ T ) = 2 × 10 –5 K (0.95 level of confidence); ε i and ε f are the heat capacity of the contents of the bomb in the initial and final states, respectively; Δ c u ′ and Δ c u ″ are the specific combustion energies of the auxiliary compounds (paraffin and cotton): the energy of the combustion of paraffin wax (P1 mark, white and odorless, GOST 23683-89) was measured as Δ c u ′ = −46,744 ± 8 J·g –1 (0.95 level of confidence) and the energy of the combustion of cotton thread (cotton thread with formula CH 1.686 O 0.843 ) is Δ c u ″ = −16736.0 ± 11.1 J·g –1 (0.95 level of confidence); Δ ign u is the energy for igniting the sample; ε is the energy equivalent of the calorimeter (14805.1 J·K –1 ); the combined expanded uncertainty is U c (ε) = 2.5 J·K –1 (0.95 level of confidence); ε cont (−Δ T c ) = ε i ( T i – 298.15) + ε f (298.15 – T i + Δ T corr ), where Δ T corr is the temperature correction for the heat of stirring and the heat exchange between the calorimeter and its environment; Δ c u soot is the average combustion energy of the soot (−32.8 kJ·g –1 ); Δ IBP u is the change of internal energy for the isothermal bomb process; Δ u (HNO 3 ) is the energy required for decomposition of the HNO 3 solution formed into N 2 , O 2 , and H 2 O­(l); Δ u corr is the energy correction to the standard state. …”

“…The heat capacity of BaP was measured on a powder material having a total mass of 0.1958 g (0.1959 g after air buoyancy correction, ρ = 1.351 g·cm –3 ). Liquid nitrogen and helium were used to reach cryogenic temperatures in two different sets of C p,m ° ( T ) determinations.…”