Chemistry of the phenoxathiins. III. Synthesis of benzo[1″,2″:5,6:5″,4″:5′,6′]bis[1,4]oxathiino[3,2-b:3′,2′-b']dipyridine

As a result of studies dealing with the synthesis of 1-azaphenoxathiins, the synthesis of benzo[1″,2″:5,6:5″,4″:5′,6′]bis[1,4]oxathiino[3,2-b:3′,2′-b']dipyridine was examined. Unique evidence of solvent participation in the synthesis of these compounds by the structure elucidation of a novel minor by-product formed during the synthesis of the title compound is also reported.     

A sensitive colorimetric determination of 2,2′-dihydroxybiphenyl

Summary A colorimetric method for the determination of 2,2-dihydroxy-biphenyl in rat urine is described. The ether extract is subjected to thin-layer chromatography on silica gel-G plates in the solvent system benzene-methanol (8020) and spots corresponding to 2,2-dihydroxybiphenyl and its glucuronide derivative are eluted with ethanol. The glucuronide is hydrolysed with HCl and the 2,2-di-hydroxybiphenyl content is determined after colour development with sodium cobaltinitrite, the absorbance being read at 410 nm. The method is sensitive and reproducible. It obeys the Lambert-Beer law in the concentration range 0.7–8.9g/ml.

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Eine empfindliche kolorimetrische Methode zur Bestimmung von 2,2 -Dihydroxybiphenyl

Zusammenfassung Eine kolorimetrische Methode zur Bestimmung von 2,2-Dihydroxy-biphenyl in Rattenharn wurde beschrieben. Der ätherische Extrakt wird auf Silikagel-G-Platten dünnschicht-chromatographisch mit dem Lösungsmittelsystem Benzol-Methanol (8020) getrennt. Die dem genannten Stoff und seinem Glucuronid entsprechenden Flecken werden mit äthanol eluiert. Das Glucuronid wird mit Salzsäure hydrolysiert und der Gehalt an 2,2-Di-hydroxybiphenyl nach Ausführung der Farbreaktion mit Natriumkobalti-nitrit und Messung bei 410 nm bestimmt. Das Verfahren ist empfindlich und gut reproduzierbar. Es entspricht dem Lambert-Beerschen Gesetz zwischen 0,7 und 8,9g/ml.

     

Decarboxylation syntheses of transition metal organometallics,II.trans-carbonyl(polyhalogenophenyl)bis(triphenylphosphine)rhodium(I) compounds

Summary The rhodium(I) carboxylates,trans-RhO₂CR(CO)(PPh₃)₂ (R = C₆F₅, C₆Cl₅,p-HC₆F₄,m-HC₆F₄,o-HC₆F₄,p-McOC₆F₄, 4,5-H₂C₆F₃, 3,5-H₂C₆F₃, or 2,6-F₂C₆H₃, have been prepared by reaction of RhH(CO)(PPh₃)₃ with the appropriate polyhalogenobenzoic acids in ethanol and/or by reaction oftrans-RhCl(CO)(PPh₃)₂ with the appropriate thallous carboxylates in benzene. Decarboxylations with formation of polyhalogenoarylrhodium(I) compounds,trans-RhR(CO)(PPh₃)₂ (R = C₆F₅, C₆Cl₅,p-HC₆F₄,m-HC₆F₄,p-MeOC₆F₄, 4,5-H₂C₆F₃ or 3,5-H₂C₆F₃), have been achieved either by decomposition of the corresponding rhodium(I) carboxylates in pyridine or by reaction oftrans-RhCl(CO)(PPh₃)₂ and the thallous carboxylates in pyridine, but the derivatives R =o-HC₆F₄ or 2,6-F₂C₆H₃ could not be obtained by this method. The rate of decarboxylation decreased in the sequence R = C₆F₅ >p-MeOC₆F₄ >p-HC₆F₄ >m-HC₆F₄ > 4,5-H₂C₆F₃ > 3,5-H₂C₆F₃.Part 1, ref. 10.Preliminary communication, ref. 9.     

Studies of pyrolysis and air heating of rayon by inverse gas chromatography

Inverse gas chromatography using water probing at 110°C was carried out to characterize rayon yarns after prior heating at 200 and 250°C in both inert (nitrogen) and oxidative (dry air) atmospheres for successively longer time intervals. During the early stages of heating in either atmosphere, the affinity of the rayon for water drops rapidly. However, whereas continued heating in N₂ results in a further loss of activity, data have been obtained showing that after an initial period yarns heated in air at 250°C exhibit an increasing attraction for water even while losing more weight.     

Studies on the ozone depletion hypothesis by chlorofluorocarbons : two-dimensional stratospheric modelling and implications for stratospheric chemistry.

A two-dimensional (2-D) model of the atmosphere including photochemistry as complete as that in advanced 1-D models, parameterized transport, diurnal effects and rayleigh scattering has been used to calculate present day altitude profiles of trace species mixing ratios.The structure and content of the model will be described and a comparison of model results with atmospheric measurements will be presented.In particular, while there had been some expectation that inclusion of latitudinal and seasonal effects would resolve certain major discrepancies for atmospheric chlorine species, the current profiles for 30 degrees latitude are qualitatively similar to 1-D model results and seasonal variations are relatively small. The principle discrepancies between 1-D model results and measurements including overstimation by the model of ClO concentrations below 30 km and understimation of HCl above 30 km are still present in the 2-D model results.The absence of change in HCl also imploies that over-estimation of HF/HCl ratio above 20 km remains a problem.The implications for model validation and ozone depletion calculations, in the view of the effect of chlorofluorocarbons, will be discussed.     

Restricted rotation about the boron---nitrogen bond in aminoboranes

The application of variable temperature ¹³C NMR to the study of a series of chlorodialkylaminophenylboranes has enabled G values for the rotational barrier, about the boron---nitrogen bond, to be determined.     

Calculation of Siegert eigenvalues for molecular systems: results for He(21,3S)+ H

The variational calculation of Siegert eigenvalues has previously been shown to provide reliable positions and widths for atomic resonances. This approach is herein extended to molecular problems, and the first such calculations for a molecular autoionizing system, He(2^1,3S)+H→ He+H⁺+e^?, are reported.     

Laser induced fluorencence matrix study of 1,3-difluorobenzene radical cation

Laser induced fluorescence excitation and resolved emission spectra of 1,3-C₆H₄F⁺₂ are obtained in a Ne matrix with high signal/noise despite the ion's low emission quantum yield. The ground state vibrational structure is mostly regular but that of the upper is very irregular suggesting nearly degenerate, mutually perturbing, excited states.