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Different supramolecular motifs are formed by the crystallisation of amino-substituted derivatives of quinoxaline, pyrimidine and pyridazine. These were made from the corresponding mono- or dichlorinated heterocycles by a nucleophilic displacement reaction. The pyridine-type nitrogen atoms activate the chlorine atoms because they can stabilise a negative charge, which forms when the amine attacks the ring. One amino group can be attached under mild conditions in hot ethanol or acetonitrile, but the first then deactivates the ring so the second requires more forceful conditions using a pressure vessel at 150 °C. Butylamine is frequently used because it reduces the polarity of the product, making it easier to purify and isolate. The extended structure of the quinoxaline derivatives 16–18 show a common 'pincer' hydrogen-bond motif, with a quinoxaline nitrogen atom accepting two N–H···N hydrogen bonds, giving a spiral or helical axis. The chain symmetries are 41, 21 and 31, respectively, depending on the substituents. A stereoview of each is shown. The pyrimidine derivatives 19, 12, 20, 14 and 21 form hydrogen-bonded tapes and compound 20 forms inversion dimers. [ABSTRACT FROM AUTHOR]

2,4-Difluoronitrobenzene has been reacted with a linker diamine (ethylenediamine or propylenediamine) and butylamine, in either order, to give new molecular building blocks for porous supramolecular networks. Two structures were established by X-ray single crystal structure determinations. The propylenediamine structure displays small pores, which may be due to the longer and more flexible linker in the structure. [ABSTRACT FROM AUTHOR]

Five historical green dyes from the Historische Farbstoffsammlung, Technical University of Dresden, have been analysed by liquid chromatography – mass spectrometry (LC-MS). The dyes were determined to be formed by the alkylation of either crystal violet or rosaniline and contained both doubly and singly charged ions. One sample had a spread of higher molecular weight doubly charged ions reminiscent of the alkylation of a Hofmann violet. Malachite green was the dye present in one sample. [ABSTRACT FROM AUTHOR]

p -Phenylenediamine reacts with Sanger's reagent in hot ethanol to give the expected mono- and di-substitution products, but in ethanol at room temperature, it gave exclusively 2-nitro-5-fluorophenyl- p -phenylenediamine, where a hydrogen atom is displaced by attack at an activated, unsubstituted position. The reactions of p -phenylenediamine and aniline with Sanger's reagent were compared in the cheap, 'green' solvent ethanol. An unexpected product forms from reacting Sanger's reagent with p -phenylenediamine [ABSTRACT FROM AUTHOR]

2-Aminobenzylaniline was ditosylated and gave an unexpected product N,N-ditosylamino-2-benzylaminobenzene in which the primary amine had ditosylated, and the benzylamine was unreacted. The benzylamine, although more electron rich, is sterically crowded and less nucleophilic than the primary amine in this ditosylated system. Sterically crowded tosylamides were prepared by reacting o-phenylenediamine, p-phenylenediamine and 1,8-diaminonaphthalene with tosyl chloride. [ABSTRACT FROM AUTHOR]

Holliday's industrial dye synthesis of 1865 was repeated by heating aniline hydrochloride with nitrobenzene and the products were characterised by modern spectroscopic methods. A red dye was isolated in low yield and characterised by an X-ray single-crystal structure determination as 9-phenyl-3-anilinophenazone-2-anil. The structure was identical to that made 93 years later in 1958 by the oxidation of 2-aminodiphenylamine hydrochloride with FeCl3 followed by heating the two products with aniline. An X-ray single-crystal structure determination was obtained for an isomer of anilinoaposafranine. A proposal is made that 9-phenyl-3-anilinophenazone-2-anil, isolated from Holliday's synthesis, arises via the oxidation and dimerisation of 2-aminodiphenylamine with hot nitrobenzene so there is a common intermediate in both syntheses. [ABSTRACT FROM AUTHOR]

Liquid chromatography–mass spectrometry has been used to analyse a range of cationic aniline dyes from the 19th century. Mauveine from the Chandler museum is used as a standard for comparison. This consists of a typical W. H. Perkin mixture of mauveine A and B. Mauveine from a historic collection in Dresden is different and consists of mainly mauveine A and a monomethyl mauveine chromophore. Possible synthetic routes and its significance are discussed. Three samples of phenylated rosanilines have been analysed, and a list of 19 possible components compiled. An analysis by liquid chromatography–mass spectrometry works well on this complex mixture giving clear information on retention times and accurate mass molecular weights. Mono-, di- and triphenylrosanilines are present in two samples, and a third sample has mainly monophenylrosaniline. In each sample, a small amount of higher molecular weight homologues appear. The thin-layer chromatography plate, from left to right, has fuchsin or rosaniline then mono-, di- and triphenylrosaniline. The two spots on the right-hand side are blue, and the two spots on the left-hand side are red. [ABSTRACT FROM AUTHOR]

A radical approach to late-stage functionalization using photoredox and Diversinate™ chemistry on the Open Source Malaria (OSM) triazolopyrazine scaffold (Series 4) resulted in the synthesis of 12 new analogues, which were characterized by NMR, UV, and MS data analysis. The structures of four triazolopyrazines were confirmed by X-ray crystal structure analysis. Several minor and unexpected side products were generated during these studies, including two resulting from a possible disproportionation reaction. All compounds were tested for their ability to inhibit the growth of the malaria parasite Plasmodium falciparum (3D7 and Dd2 strains) and for cytotoxicity against a human embryonic kidney (HEK293) cell line. Moderate antimalarial activity was observed for some of the compounds, with IC50 values ranging from 0.3 to >20 µM; none of the compounds displayed any toxicity against HEK293 at 80 µM. [ABSTRACT FROM AUTHOR]