Treibs

P. Kassengeck, Faktoren, die das Nitrierverhalten von Baumwoll-Einters undHolcyyellstoffen beeinflussen, report 3/83, ICT-Fraunhofer-Institut fur Treib-und Explosivstoffe, 1983. 

The tautomeric equilibrium between 112 and 113 has been studied by Treibs and his associates. Most pyrromethenes take form... 

E. Treibs Views on the Nature of the Acid Catalysis of Electrophilic Substitution in Pyrroles.298... 

Treibs and Kolm have reported that, in the complete absence of oxygen and in the dark, pyrrole dissolves in 1.05 equivalents of 0.75 lY aqueous HCl—the clear solution is stable for several hours at room temperature and on basification gives unchanged pyrrole in high yield. (This was difficult to achieve, for the authors state that only two out of four experiments succeeded.) It is very difficult to understand how pyrrole, with an extremely low pKa of the order of zero, can dissolve in 1 equivalent of dilute aqueous acid (1.4 gm pyrrole in 32 ml of aqueous acid). Treibs concludes that protonated pyrrole is stable in solution, and that it is extremely susceptible to autoxida-... 

In several papers,Treibs argues that the effect of acid on the interaction of pyrroles with electrophilic reagents is to increase the susceptibility of the pyrrole nucleus to electrophilic attack the proton donor is believed to convert the pyrrole nucleus transiently and reversibly into what is described as a salt of an azacyclopentadienyl anion, the activation of the a-position, for example, occurring as follows, (23) being the activated species ... 

All acid-catalyzed electrophilic substitution reactions are held by Treibs to occur by way of the distinct reactive species (23), thus the very greatly accelerated interaction of pyrrole and formaldehyde in acid solution involves attack of neutral formaldehyde on (23). Another example is the interaction of 2,3,4,6-tetramethylpyrrole with p-dimethylaminobenzaldehyde in acid solution, for which the following reaction (Scheme 2) is given,(23a) being presumably intended... 

Treib-alkohol, m. power alcohol, -arbeit, /. cupellation. -asche, /. cupel ashes, bone ash. -brhhe,/. Tech.) old liquor, -eiscn, n. white pig iron,... 

Treib-strahl, m, propulsive jet. -verfahren, n. Metal.) cupellation process. 

W. Treibs, Jersualem Symp. Quantum Chem. Biochem. 3, 91 (1971). 

Pyrotechnik, Grundlagen, Technologie und An-wendung, Institut fuer Chemie der Treib und Explosivstoffe der Fraunhofer Gesellschaft, Karlsruhe, Ger (11—13 June 1975) 157) Anon,... 

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