Comparison of the Profiles of Polycyclic Aromatic Hydrocarbons in Different Areas of a City by Glass-Capillary-Gas-Chromatography in the Nanogram-Range

Since the PAH-mixture of different emittants such as coal heatings, oil heatings or gasoline engines are different and therefore characteristic, it is to be expected, that these PAH-profiles are helpful to recognize the main sources of an air pollution. Furthermore, this investigation compares the local concentrations of several selected PAH and records the temporary variation in PAH-profiles of different areas in a city during the year.

The collecting system consists of a low volume air sampler, connected with a glass fibre filter (490cm²). To separate the mixture of PAH glass-capillary-gas-chromoatography is used and 15 PAH are selected for this investigation (splitless injection, Silicone OV 17). The repeatability of the total collecting procedure and for the analysis is satisfactory.

Four areas have been selected inside the city: I. area with hand-stoked residential coal heatings, II. area with oil heatings preferentially, III. stations in a tunnel with automobile traffic, IV. area surrounding a coke plant.

The PAH-profiles differ in many cases from area to area and the concentrations of all PAH regarded (including benzo(a)pyrene) vary strongly during the day, week and year on the same place, even during the heating period for the 16 collecting stations investigated monthly (e.g. in case of BaP at the same place from 1.6 ng/m³ to 299 ng/m³).

Especially the distribution pattern of 4 PAH (BcPH, CYC, BghiP, COR) is completely different from the other PAH's recorded in the city. The first one correlates to the automobile traffic in the tunnel.     

11B-MAS-NMR-Untersuchungen zur Anionenstruktur von Boraten

¹¹B MAS NMR Studies on the Structure of Borate Anions The results of ¹¹B MAS NMR studies on selected crystalline borates and peroxoborates show that the boron coordination number can be determined not only from the quadrupole coupling constant but also from the chemical shift values. Correspondingly, the B[3]:B[4] ratio can be determined quantitatively. In contrast to ²⁷Al, ²⁹Si, and ³¹P NMR data, however, the observed small variation of the ¹¹B chemical shifts does not allow a more detailed information on the linkage of the coordination polyhedra and their environments. The method was applied to Ag borates with unknown structures. In the case of a borate with an Ag:B ratio of 1:3 the measured B[3]:B[4] ratio suggests a triborate structure of the anion.     

An Enamide‐Based Domino Reaction for a Highly Stereoselective Synthesis of Tetrahydropyrans

A novel method for the highly stereoselective synthesis of tetrahydropyrans is reported. This domino reaction is based on a twofold addition of enamides to aldehydes followed by a subsequent cyclization and furnishes fully substituted tetrahydropyrans in high yields. Three new σ‐bonds and five continuous stereogenic centers are formed in this one‐pot process with a remarkable degree of diastereoselectivity. In most cases, the formation of only one out of 16 possible diastereomers is observed. Two different stereoisomers can be accessed in a controlled fashion starting either from an E‐ or a Z‐configured enamide.     

Bestimmung des Gesamtgehaltes aller polycyclischen aromatischen Kohlenwasserstoffe in Luftstaub und Kraftfahrzeugabgas mit der Capillar-Gas-Chromatographie

Zusammenfassung Es wird ein Anreicherungsverfahren und die capillar-gas-chromatographische Bestimmung von polycyclischen aromatischen Kohlenwasserstoffen beschrieben. Zur quantitativen Auswertung werden die Flächen der F.I.D.-Signale mit zwei inneren Standards verglichen. Kraftfahrzeugabgas und Luftstaub aus Industriegebieten unterscheiden sich durch charakteristische Mengenrelationen von Benzo(a)pyren zu Anthanthren, Benzo(ghi)perylen und Coronen. Antwort: Die Identifizierung erfolgte nicht nur mit Originalsubstanzen, sondern auch durch die Kombination GLC/MS.     

Phosphorus-31 MAS NMR investigations of pyridine stabilized dithiomonometaphosphoryl halides

Phosphorus-31 magic-angle spinning NMR spectroscopy was chosen in order to study a series of N-donor stabilized dithiomonometaphosphoryl halides (F, Cl, and Br) and to extract structural and bonding information from their spectra. Additionally, an unusual line splitting was observed in the 31P MAS NMR spectra of pyridine dithiomonometaphosphoryl chloride (Py-->PS2Cl) and the analogous bromide (Py-->PS2Br). It is shown that this effect is due to a residual dipolar coupling between phosphorus and chlorine or bromine, respectively. This work is to our knowledge the first observation of this effect between P and Br in 31P MAS NMR spectra.