Bemerkungen zur Synthese von 5‐Amino‐m‐xylol‐2‐sulfonsäure und 5‐Amino‐m‐xylol‐4‐sulfonsäure

Abstract

Some comments on the syntheses of 5-amino-rn-xylene-2-sulfonic acid and 5-amino-m-xylene-4-sulfonic acid SummaryTreatment of 5-amino-m-xylene (1) with oleum led to a 55:45 mixture of 5-amino-m-xylene-2-sulfonic acid (2) and 5-amino-m-xylene-4-sulfonic acid (3). The structure of both isomers was proven by reaction of sulfur dioxide with the diazonium chlorides derived from 2-amino-5-nitro-rn-xylene (5) and 4-amino-5-nitrom-xylene (8) giving 5-nitro-m-xylene-2-sulfonyl chloride (6) and 5 -nitro-m-xylene-4-sulfonyl chloride (9) respectively, followed by hydrolyses to the corresponding sulfonic acids 7 and 10, and final Bkchamp reductions. The sulfonic acid 2 was also prepared by sulfonation of 5-acetylamino-m-xylene (4) to 5-acetylamino-m-xylene-2-sulfonic acid (11) and subsequent hydrolysis. A further procedure for the synthesis of 3 was sulfonation of 5-amino-2-chloro-m-xylene (12) -prepared by Bdchamp reduction of 2-chloro-5-nitro-m-xylene (13) -or of 5-amino-2-bromo-mxylene (15) -prepared by bromination of 4 and subsequent hydrolysis -to 5-amino-2-chloro-m-xylene-4-sulfonic acid (16) and 5-amino-2-bromo-m-xylene-4-sulfonic acid (17) respectively, followed by hydrogenolysis.Synthesen der beiden von 5-Amino-m-xylol (1) herleitbaren Sulfonsauren, 5-Amino-m-xylol-2-sulfonsaure (2) und 5-Amino-m-xylol-4-sulfonsaure (3), sind nicht bekannt. Einzig fur 5-Acetylamino-m-xylol (4) ist die Reaktion mit Chlorsulfonsaure zu 5-Acetylamino-m-xylol-2-sulfonylchlorid beschrieben [ 11.Bei der Reaktion von 1 mit Oleum wurde gemass Dunnschichtchromatogramm vollstandige Umsetzung unter Bildung zweier sulfonierter Produkte beobachtet. Das NMR.-Spektrum') des isolierten Gemisches in einer Losung von deuteriertem Natriumhydroxid in Deuteriumoxid zeigte bei 6,61 ppm ein einziges Signal fur aromatische Protonen, sowie ein Signal bei 4,78 ppm fur austauschbare Protonen und zwei Signale fur Methylprotonen bei 2,57 ppm und 2,20 ppm. Unter der sich spater bestatigenden Annahme, dass ein Gemisch der Sauren 2 und 3 vorlag, musste das Signal bei 2,57 ppm den Protonen der in o-Stellung zu einer Sulfonsauregruppierung stehenden Methylgruppen und das Signal bei 2,20 ppm den Protonen der sich in I) Die chemischen Verschiebungen 6 sind in ppm angegeben; vgl. exper. Teil.

Preparation and Properties of Phosphaethynes Bearing Bulky Aryl Groups with Electron-Donating Substituents at the Para Position

“…The method for the preparation of 1c by Rundel 12a starting from 4-nitro-2,6-di- tert -butylaniline was found to be rather inefficient due to formation of byproducts and an elaborate separation process 12b. Therefore we prepared 1c as follows: 3,5-xylidine was brominated with NBS in acetonitrile, to give 4-bromo-3,5-xylidine (98% yield), which was then converted to 2,5-dibromo-1,3-dimethylbenzene ( 3 ) by Sandmeyer reaction with use of CuBr/HBr (38% yield). Bromination of 3 with NBS in CCl 4 gave compound 4 (55% yield), which was then cyanated with KCN to form 5 (90% yield).…”

Consecutive Ligand‐Based Electron Transfer in New Molecular Copper‐Based Water Oxidation Catalysts

“…The total TON values can be obtained from the oxygen evolution experiment taking in account the total amount of catalyst present in the solution by using equation (2). However, since only the catalyst present in the layer of the solution in contact with the electrode is involved in the water oxidation reaction, this TON value is underestimated.…”

“…The ligand precursor ([2,2'-bipyridine]-6,6'-dicarboxylic acid) and 5-amino-m-xylol-4-sulfonic acid were prepared according to the experimental procedure reported in the literature. 1,2 Air and moisture sensitive reactions were carried out under N2 or Ar in oven-dried (120 °C) glassware. Evaporation of solvents in vacuo was done with a Büchi Rotevapor R-200 at 40 °C.…”