A coated piezoelectric crystal detector for the selective detection and determination of hydrogen sulfide in the atmosphere

A method for the selective detection and determination of hydrogen sulfide in the atmosphere is presented. This method utilizes the reversible adsorption of H₂S on a piezoelectric quartz crystal coated with an acetone extract of soots resulting from the burning of organochlorine compounds. The extract of a soot prepared from chlorobenzoic acid provided the best substrate. The method is useful in the concentration range 1–60 ppm.     

Formation of m- and p-xylenes during dehydrocyclization of n-octane on chromium oxide catalysts

Conclusions In the dehydrocyclization of n-octane the m- and p-xylenes are formed as a result of the isomerization of the carbon skeleton of the aliphatic intermediate products of the reaction, namely the octadienes and octatrienes.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1675–1676, July, 1973.     

Ionization and Tautomerism of Hydroxyxanthenes and Some Other Dyes in Ethanol

Protolytic equilibria of hydroxyxanthene dyes, Fluorescein, Eosin, as well as of some relatedcompounds, in ethanol were studied by spectrophotometry. Stepwise ionization and tautomeric equilibriumconstants were determined.     

The Claisen-Schmidt reaction with heterocyclic analogs of o-hydroxyacetphenone

Claisen-Schmidt condensation of 4-hydroxy-3-acetyl-6-methylpyrid-2-one, and its N-methyl and N-phenyl derivatives with aromatic aldehydes is investigated, and it is shown that the products of this reaction are 3-cinnamoyl and not 6-styryl derivatives.     

S=N versus S+-N-: an experimental and theoretical charge density study

To elucidate the bonding situation in the widely discussed hypervalent sulfur nitrogen species, the charge density distributions rho(r) and related properties of four representative compounds, methyl(diimido)sulfinic acid H(NtBu)(2)SMe (1), methylene-bis(triimido)sulfonic acid H(2)C[S(NtBu)(2) (NHtBu)](2) (2), sulfurdiimide S(NtBu)(2) (3), and sulfurtriimide S(NtBu)(3) (4), were determined experimentally by high-resolution low-temperature X-ray diffraction experiments (T = 100 K). This set of molecules represents an ideal frame of reference for the comparison of SN bonding modes, because they contain short formal S=N double bonds as well as long S-N single bonds, some of them influenced by inter- or intramolecular hydrogen bonds. For comparison, the gas-phase ab initio calculations of the four model compounds, H(NMe)(2)SMe, H(2)C[S(NMe)(2)(NHMe)](2), S(NMe)(2), and S(NMe)(3), were performed. The topological features were found to be not particularly sensitive with respect to different substituents R (R = H, Me, tBu). In this paper, it is documented that theory and experiment differ in the eigenvalues of the Hessian matrix because of systematically differing positions of the bond critical points but agree very well concerning the spatial Laplacian distribution and the distinct polarization of all investigated sulfur-nitrogen bonds. Both recommend the S(+)-N(-) formulation of sulfur nitrogen bonds in 1 and 2 since all nitrogen atoms are found to be sp(3) hybridized. The planar SNx (x = 2, 3) units in the diimide 3 and the triimide 4 reveal characteristics of m-center-n-electron systems. For none of the investigated S-N bonds, a classical double bond formulation can be supported. This is further substantiated by the NBO/NRT approach. Valence expansion to more than eight electrons at the sulfur atom can definitely be excluded to explain the bonding.     

Low-dimensional chainlike assemblies of TiO2 nanorod-stabilized Au nanoparticles

A simple and versatile light-based strategy to grow low-dimensional gold superstructures is presented; prolonged UV-irradiation of TiO2 nanorod-stabilized Au nanoparticles in organic media promotes the progressive formation of distinctive chainlike metal assemblies, namely segments of a few gold particles, 2D or quasi-1D large structures composed of interlacing lines of hundreds of metal units over areas of about 500 nm2.