Bemerkungen zur Synthese von 3-Aminotoluol-5-sulfonsäure und 2-Aminotoluol-3-sulfonsäure

Some comments on the synthesis of 3-aminotoluene-5-sulfonic acid and 2-aminotoluene-3-sulfonic acid. Sulfonation of 3-nitrotoluene ( 5 ) yields predominantly the unsymetrical isomer 5-nitrotoluene-2-sulfonic acid ( 7 ), and lesser amounts of 5-nitrotoluene-3-sulfonic acid ( 6 ), previously reported as the major product. The desired 5-aminotoluene-3-sulfonic acid ( 3 ) was synthesized in preparative amounts from 6-aminotoluene-3-sulfonic acid (4) via the following sequence of reactions: diazotation and Sandmeyer replacement of 6-chlorotoluene-3-sulfonic acid ( 13 ), nitration of the sulfonyl chloride 14 under suitable conditions to give isomer free 6-chloro-5-nitrotoluene-3-sulfonyl chloride ( 15 ), hydrolysis to the sulfonic acid 16 and finally, simultaneous hydrogenolysis and reduction to 3 . The isomeric 7 was unequivocally prepared from 2-amino-5-nitrotoluene ( 9 ) via two routes: (1) diazotation, Sandmeyer thiocyanatation to 5-nitro-2-thiocyanatotoluene ( 10 ), Na₂S reduction to the di(2-methyl-4-nitro-phenyl)-disulfide ( 11 ), treatment with nitric acid and chlorine to give 5-nitrotoluene-2-sulfonyl chloride ( 12 ) and finally alkaline hydrolysis to 7 ; (2) Meerwein's SO₂ treatment of the diazonium salt derived from 9 leads directly to 12 and thence to 7 . 2-Aminotoluene-3-sulfonic acid ( 1 ) was prepared from the key intermediate 3-amino-2-nitrotoluene ( 18 ) via the same two routes used to prepare 7 from 9 . Both reaction sequences provided 2-nitrotoluene-3-sulfonly chloride, the hydrolysis product of which was reduced to 1 . Intermediate 18 was prepared in the following four steps from m-toluic acid ( 19 ): nitration to the 2-nitroderivative ( 20 ), whose acid chloride ( 21 ) was converted to 2-nitro-m-toluamide ( 22 ), and Hoffmann rearrangement to 18 .     

Eine neue Methode zur volumetrischen Bestimmung von Phosphit und Hypophosphit nebeneinander

Zusammenfassung Zur Bestimmung von phosphoriger und von unterphosphoriger Säure in Bädern zur stromlosen Herstellung von Metallüberzügen werden zwei neue Methoden beschrieben.Unterphosphorige Säure wird mit Silberperchlorat oxydiert und der Überschuß an Silberionen mit Natriumchlorid zurücktitriert. Die Summe von phosphoriger Säure und unterphosphoriger Säure wird bromatometrisch in 0,11 N salzsaurer Lösung bestimmt. Zur Erfassung der phosphorigen Säure eignet sich das von Norkus, Lunjackas u. Carankute beschriebene jodometrische Verfahren.

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Summary Two new methods are described for the determination of phosphorous and hypophosphorous acid in bath solutions for the production of metal coatings without current. Hypophosphorous acid is oxidized with silver perchlorate and the excess of silver ions is back-titrated with sodium chloride. The sum of phosphorous and hypophosphorous acid is determined bromatometrically in 0.11 N hydrochloric acid solution. Phosphorous acid can be determined by the iodometric procedure according to Norkus, Lunjackas and Carankute.

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1 Diplomarbeit, Bergakademie Freiberg 1967.     

Biochemical Aspects of Cholinergic Excitation

A prerequisite for every biological system to develop and to continue to function (“to live”) is an effective communication between its components, i.e. its cells. This intercellular communication is essentially of a chemical nature: It employs neurotransmitters and hormones as messengers, and receptors as the receivers of transmitted signals. As is typical for all communication systems, biological signal processes usually also utilize only relatively small amounts of material. This general rule, however, does not apply to some synaptic communication systems. One typical exception, for instance, is the nerve-muscle synapse and, in particular, its special form, the nerve-electroplaque synapse of electric fish. These systems, therefore, lend themselves to biochemical studies permitting investigation of the molecular basis of biological communication processes. Thus, the acetylcholine receptor of the plasma membrane of the postsynaptic cell was established as a structurally and functionally rather complicated “transducer system” responsible for both the reception of the chemical message and its conversion into an electrical activity of the receiving cell.     

Palladium-promoted Cyclization of Tetra-alkylated 1-Arylazonaphthalenes to 2-Aryl-benzo[g]indazoles

1-Arylazonaphthalenes with all the potential cyclopalladation sites (one peri- and three ortho-positions) substituted by methyl or ethyl groups react with stoicheiometric or catalytic amounts of sodium tetrachloropalladate(II) to the corresponding 2-arylbenzo[g]indazoles. Possible mechanisms for the catalytic cyclization reaction are proposed.     

Glucose,not cellobiose,is the repeating unit of cellulose and why that is important

Despite nomenclature conventions of the International Union of Pure and Applied Chemistry and the International Union of Biochemistry and Molecular Biology, the repeating unit of cellulose is often said to be cellobiose instead of glucose. This review covers arguments regarding the repeating unit in cellulose molecules and crystals based on biosynthesis, shape, crystallographic symmetry, and linkage position. It is concluded that there is no good reason to disagree with the official nomenclature. Statements that cellobiose is the repeating unit add confusion and limit thinking on the range of possible shapes of cellulose. Other frequent flaws in drawings with cellobiose as the repeating unit include incorporation of O-1 as the linkage oxygen atom instead of O-4 (the O-1 hydroxyl is the leaving group in glycoside synthesis). Also, n often erroneously represents the number of cellobiose units when n should denote the degree of polymerization i.e., the number of glucose residues in the polysaccharide.