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Three bleached and subsequently aged cellulosic pulps have been analysed for their chromophore content according to the chromophore release and identification (CRI) method. Several chromophores have been unambiguously identified, despite their very low content (ppb range). This is the first report on defined chromophoric structures isolated from bleached pulps. It is also the first application of the CRI method to cellulose I substrates, rather than to cellulose II substrates (fibres) and cellulose derivatives as hitherto performed. A common feature of the chromophores is the 2-hydroxy-[1,4]benzoquinone moiety, which is strongly stabilized by resonance or tautomerism. The structure of the chromophores indicates that oxidised carbohydrate structures act as precursor moieties, which condense upon ageing to the chromophore structures identified.

Bleaching is an important part of the production of paper and textiles. On industrial scale bleaching of fibres for these processes is the by far most important application of several chemicals. Theoretically, nearly all oxidising and reducing compounds could be used in bleaching, however, in technical practice just a handful of compounds is applied. A short description of the industrially important chemicals is presented, these are oxygen, chlorine dioxide, hydrogen peroxide, sodium dithionite and ozone. Their combination in bleaching processes is described and completed by an illustration of their typical limitations. The potential for removing colour and improving brightness stability is shown.

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Summary The mass spectral behaviour, especially loss of NH,, of the six isomeric cyclohexanediamines 1-3 (cis and trans each, Scheme I) as well as of the six isomeric bis (aminomethy1)cyclohexanes 4-6 (cis and trans each, Scheme 6) has been investigated. The cis-and trans-compounds of the 1,2-isomers 1 and 4 show very similar spectra, because of the ease of ring cleavage at C(1)-C(2) and the similar geometrical relations in all ring conformations. The cis-and trans-compounds of both the 1,3-and 1,Cisomers 2, 3, 5 and 6 show striking differences in their mass spectra due to stereospecific elimination of NH, from the molecular ion.In der voranstehenden Mitteilung [ 11 berichteten wir iiber den massenspektrometrischen Zerfall der Diacylderivate der Titelverbindungen. Es zeigte sich, dass bei den Diacetylderivaten keine signifikanten stereospezifBchen Fragmentierungen auftreten, die zur Unterscheidung von cis-und trans-Isomeren heranzogen werden konnten. Demgegeniiber zeigen die N-Acetyl-N'-benzoyl-N'-phenathyl-Derivate der Cyclohexandiamine eine ausgepragte Stereospezifitat beim massenspektrometrischen Zerfall.In der vorliegenden Arbeit berichten wir iiber das Fragmentierungsverhalten von Cyclohexandiaminen und Bis (aminomethyl)cyclohexanen, insbesondere iiber stereospezifische NH3-Abspaltungen. 1.Cyclohexandiamine. -Es wurden die cis-und trans-Isomeren der 1,2-, 1,3-und 1,CCyclohexandiamine (1-3) untersucht sowie von den I,3-und 1,4-I) 32.Mitt. s. [I].