�ber einen neuen Bestandteil des Buchenholzes

Wedekind, E.; Müller, O.

doi:10.1007/bf01491920

Cited by 2 publications

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“…The reduction may go further, an arylamine being split off and N-arylamidrazones (IV and V) formed (Bamberger & Gruyter, 1893a, b;1901;Bamberger & Witter, 1893;Voswinckel, 1903). However, if the formazan is precipitated from solution as soon as it is formed, no more reduction takes place (Wedekind, 1896). This is essentially what happens in the reduction of tetrazolium salts in tissue sections.…”

Section: LImentioning

confidence: 99%

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Histochemical studies of the formazan reaction: III. The reversible oxidation‐reduction of mucosubstance formazans

Stoward

1967

Journal of the Royal Microscopical Society

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SYNOPSIS In sections of fixed tissue, periodate‐oxidized mucosubstances that have been treated firstly with Phenylhydrazine and secondly at a pH near 9 with a diazonium salt, such as diazotized aniline or tetrazotized 3,3′‐dimethoxybenzidine, are converted into highly‐coloured derivatives which could be formazans, azo‐compounds, tetrazenes, or a mixture of these. That such derivatives are in fact mostly, if not exclusively, formazans has been confirmed by treating these derivatives in situ firstly with N‐bromosuccinimide, to oxidize acid‐labile formazans into acid‐stable, colourless tetrazolium salts; secondly, with a hot ethanolic solution of hydrochloric acid, to destroy azo‐derivatives and tetrazenes and leave tetrazolium salts untouched; and thirdly, with an aqueous solution of ammonium sulphide, to reduce the mucosubstance tetrazolium salts back to the original coloured formazans.

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Section: LImentioning

confidence: 99%

“…111 the NAS procedure. Tetrazolium salts are remarkably stable towards hot mineral acids (Pechmann & Wedekind, 1895;Wedekind, 1896;Ashley et al, 1953) in comrast to formazans (Bamberger & Wulz, 1891;Bamberger & Wheelwright, 1902;Bamberger & Witter, 1902;Pechmann, 1894), tetrazenes and azo derivatives which are readily broken down.…”

Section: LImentioning

confidence: 99%

Histochemical studies of the formazan reaction: III. The reversible oxidation‐reduction of mucosubstance formazans

Stoward

1967

Journal of the Royal Microscopical Society

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Zur chemie des lignins

Müller

1976

Angew. Makromol. Chem.

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ZUSAMM ENFASSUNG :,,Brauns"-Lignin liefert in 74,9proz. Schwefelsaure eine Hydrolysen-Kurve, die nicht die am nativen Lignin nachgewiesenen Abspaltungs-und Anlagerungsvorgange von Wasser erkennen lal3t; es kann also nicht identisch mit der nativen Form des Lignins sein. ,,Brauns"-Lignin enthalt eine Zuckerkomponente, die kein wasserunlosliches Saccharid ist.Buchenschwefelsaurelignin laDt beim Kaltpressen unter hohem Druck ein plastisches FlieDen erkennen und hat danach eine Dichte von 1,24 bis 1,28g/cm3. -Versucht man, Buchenschwefelsaurelignin in eine Caprolactamschmelze einzupolymerisieren, so erhalt man eine hellbraune, metallisch glanzende Masse. Aber bereits bei Ligninmengen von weniger als 1% ist das Abspinnvermogen stark beeintrachtigt. Offenbar ist das dreidimensionale Ligninmolekul so starr, dal3 es die lineare Ausrichtung des Polymerisates und damit die Fadenbildung stort.Es gelingt, Fichtenschwefelsaurelignin in waDriger, schwach essigsaurer Suspension mittels Natriumchlorit in eine hochgequollene, transparente, orangefarbene Masse zu verwandeln. -Der weitere oxidative Abbau mit einem Gemisch von Wasserstoffperoxid, Essigsaureanhydrid und Eisessig fuhrt zu sauren Produkten, deren weitere Trennung uber ihre Bleisalze mit unterschiedlichen Loslichkeiten gelingt, und die auch als freie Sauren teilweise kristallisieren. Fur eine dieser Fraktionen, welche die Hauptmenge bildet, wird eine Strukturformel zur Diskussion gestellt. SUMMARY:"Brauns"-Lignin in H,SO, of 74,9 weight % produces a curve of hydrolysation which does not show the addition on or the elimination of HzO reactions as proved with native lignin. Therefore native and "Brauns"-Lignin are not identical. "Brauns"-Lignin has a saccharid component, which is not a saccharid insoluble in water.Beechwoodlignin (sulphuric acid) shows a plastic flow after cold pressing under high pressure, and thereafter has a specific weight of 1,24-1,28 g/cm3. Incorporation of beechwood-sulphuric-acetic-lignim in the melt of polymerizing caprolactam produces a light brown, metallic shining mass. Lignin-concentration lower than 1 % strongly reduces the possibility to spin. It is possible to produce an orange coloured, transparent, strongly swollen mass from picea-sulphuric-acid-lignin in a suspension of diluted solution of acetic acid with

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�ber einen neuen Bestandteil des Buchenholzes

Cited by 2 publications

References 1 publication

Histochemical studies of the formazan reaction: III. The reversible oxidation‐reduction of mucosubstance formazans

Histochemical studies of the formazan reaction: III. The reversible oxidation‐reduction of mucosubstance formazans

Zur chemie des lignins

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