- Waste-Free Quantitative Gas/Solid Diazotation Using Nitrogen Dioxide and Triazene Synthesis, Both Avoiding Liquid Phases
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Solid diazonium nitrates (2a-j) are quantitatively obtained by reaction of crystalline anilines (1a-j) with gaseous nitrogen dioxide. Solid diazonium salts react quantitatively with dimethylamine to give the triazenes (4a-j). Wastes that are typical for the previous syntheses of these compounds in solution are avoided. Atomic force microscopic (AFM) investigations indicate long-range molecular movements due to phase rebuilding. The features thus formed are related to the known crystal structures of the starting anilines. The diazotations run to completion, because, after accumulation of product molecules, phase transformation to give the product lattices leads to crystal disintegration and thus to formation of fresh surface over and over.
- Kaupp, Gerd,Herrmann, Andreas
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p. 256 - 260
(2007/10/03)
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- AFM in organic solid state reactions
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Organic solid-state reactions are probed with the atomic force microscope (AFM). In all cases phase rebuilding gives rise to characteristic submicroscopic features which change in shape due to phase transformation in later stages of the chemical reaction. Photo-(E/Z)-isomerization of olefin 1 occurs in the crystal, photodimerization of 9-chloroanthracene 3 is used as a probe for characterizing the luminosity distribution of SNOM-tips. Gas/solid imbibition in chiral host 5 proceeds enantiospecifically. Histidine crystals form the dihydrochloride with HCl, ammonia and methylamine react face-selectively with crystalline adipic acid 8, furane-2-carboxylic acid 10 and 2-mercaptobenzothiazole 12. Crystals of olefin 14 add chlorine. Solid-state diazotations and subsequent transformations of the solid diazonium nitrates into triazenes occur quantitatively. Solid/solid pinacol- and benzilic acid rearrangements are probed with the AFM. The features formed by long range molecular movements relate to the crystal packing and are thus different on different faces. Correlations with X-ray structural data are demonstrated. All reactions proceed to completion on a preparative scale and do not produce wastes as do their less selective counterparts if performed in solution. Organic solid-state reactions, AFM, SNOM-tip, imbibition, salt formations, chlorination, diazotations, triazene, gas/solid-reactions, solid/solid-reactions, crystal packing, waste-free reactions.
- Kaupp, Gerd,Schmeyers, Jens,Haak, Michael,Marquardt, Thorsten,Herrmann, Andreas
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p. 315 - 317
(2007/10/03)
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