On the birthday of R. M.-F. Salikhdzhanova

Chronicle

On the birthday of R. M.-F. Salikhdzhanova     

Chemistry of the diazeniumdiolates. 3. Photoreactivity

We have found O(2)-substituted diazeniumdiolates, compounds of structure R(2)N-N(O)=NOR' that are under development for various possible pharmaceutical uses, to be rather photosensitive. With R = ethyl and R' = methyl, benzyl, or 2-nitrobenzyl, the observed product distributions suggest that two primary pathways are operative. A minor pathway involves the extrusion of nitrous oxide (N(2)O) with simultaneous generation of R(2)N(*) and R'O(*), which may then form amines, aldehydes, and alcohols. The major reaction pathway is an interesting photochemical cleavage of the N=N bond to form a nitrosamine (R(2)NN=O) and an oxygen-substituted nitrene (R'ON). The intermediacy of the O-nitrene was inferred from the production of abundant oxime, via rearrangement of the O-nitrene to a C-nitroso compound (R'ON --> O=NR'), and subsequent tautomerization to the more stable oxime. Involvement of the O-nitrene was confirmed by trapping with 2,3-dimethyl-2-butene to form the aziridine and with oxygen to generate the nitrate ester. 2-Nitro substitution on the benzyl derivative had surprisingly little effect on the reaction course. For each compound examined, minor amounts of nitric oxide (NO), presumably produced by secondary photolysis of the nitrosamine, were observed. Time-resolved infrared experiments provided additional support for the above reaction pathways and confirmed that the nitrosamine is a primary photoproduct. We have also found that the relative contributions of the reaction pathways can be altered in certain derivatives. For example, when R' = 2,4-dinitrophenyl, the contribution of the nitrosamine/O-nitrene-forming pathway was diminished. Pharmacological implications of these results are discussed.     

On the Use of the Knox Equation. I. the Fit Problem

Abstract

To obtain significant A, B, and C parameters of the Knox equation, which corresponds to the plot of the reduced plate height, h, versus the reduced linear velocity, v, actual results must be fitted correctly. The Knox equation is analyzed, the rôle of each individual parameter is shown. The equation producing the coordinates of the minimum plate height (maximum efficiency) is fully derived from the derivative of the Knox equation. Two tables giving the minimum coordinates for usual A, B, and C ranges are listed. The classical fit method is derived and analyzed. A graphical fit method which uses the remarkable graphical capabilities of modern spreadsheet packages is described. A synthetical set of data was fitted. It is demonstrated that each Knox parameter, obtained through fit procedures, must be given with the fitting confidence interval which is often in the 20% range.     

Research on the aromas. On the aroma of coffee. II. Pyrazines and pyridines

Pyrazines and pyridines occurring in a coffee concentrate are analyzed by two procedures. 24 compounds have been identified and the presence of some 10 more is revealed. The syntheses, mass and infrared spectral data of reference compounds are given.     

Polysaccharides ofUngernia. VII. Partial hydrolysis of the mannan of the bulbs ofU. vvedenskyi

4-O--D-Manopyranosyl-D-mannose, O--D-mannopyranosyl-(l4)-O--D-mannopyranosyl-(14)-D-mannose, and 0--D-mannopyranosyl-(14)-O--D-mannopyranosyl-(l4)-O--D-mannopyranosyl-(l4)-D-mannose have been isolated fron the products of the partial hydrolysis of ungeromannan-V, obtained fron the bulbs ofUngernia vvedneskyi, and have been identified. This set of oligosaccharides confirms the regular structure of the carbohydrate chain of ungeromannan-V, which consists of a linear sequence of -14-bound D-mannose residues.DeceasedTranslated from Khimiya Prirodnykh Soedineii, No. 4, pp. 434–436, July–August, 1981.     

Comments on the paper by Dr. C.A. McAuliffe

The first cyclopentadienylplutonium(IV) compounds, (η⁵-C₅H₅)₃PuCl and (η⁵-C₅H₅)₃Pu(NCS) have been prepared, the former by reaction of Cs₂PuCl₆ with TlC₅H₅ in CH₃CN and the latter by treating the chloride with KNCS in tetrahydrofuran. Both compounds are isostructural with ther U^IV and Np^IV analogues. The IR and UV/visible spectra of the new compounds are reported.