Terrence J. Smith

Formation of Chlorinated Phenols during Bleaching of Eucalypt Kraft Pulps

Oxygen-delignified kraft pulps from mature and young eucalypt woods were treated with chlorine (C) or chlorine dioxide (D) and subsequently with alkali reinforced with oxygen, (EO) C or (EO) D . The bleaching filtrates were examined for chlorinated phenols by the in situ acetylation-gas chromatography method. A total of 43 chlorinated phenols were identified in the C-stage and/or the (EO) C -stage filtrates, whereas only four were found in the corresponding D-stage filtrates. About half of the identified compounds were chlorinated benzaldehydes and acetophenones, and 18 chlorinated phenols have not been positively identified previously. The two chloro-3,4,5-trimethoxybenzaldehydes and 2,4,6-trichlororesorcinol identified in the filtrates probably derive from extractives originally present in the wood. There was no indication of differences in the nature of the chlorinated phenols obtained from the mature and young eucalypt samples

Factors influencing the amounts of chlorinated phenols formed during bleaching of eucalypt kraft pulps

Oxygen-delignified kraft pulps from both mature and young eucalypt wood samples were treated with chlorine (C), chlorine dioxide (D) or a mixture of the two reagents, and were subsequently extracted with alkali (E), optionally reinforced with oxygen (EO). C(EO) and D(EO) treatments were also carried out without interstage washing. The levels of Chlorinated phenols in the filtrates were estimated by an in situ acetylation technique. The 14 major Chlorinated phenols consisted of 3 catechols, 4 guaiacols, l syringol, 2 Vanillins, 2 syringaldehydes and 2 acetosyringones. Chlorinated phenolic aldehydes were the most prevalent components in the bleaching filtrates; 2,6-dichlorosyringaldehyde was the major analyte from C treatments and 2-chlorosyringaldehyde from D treatments. The amounts of Chlorinated phenols were higher in the filtrates following C treatments than in the filtrates from D treatments, and increased in the order C(or D) < E < EO < EO without interstage washing. There was a poor correlation between the levels of Chlorinated phenols and the adsorbable organic halogen (AOX)

Determination of chlorinated benzaldehydes and acetophenones in pulp bleaching effluents by gas chromatography

Abstract Application of modern sequences involving chlorine, chlorine dioxide and oxygen—alkali to the bleaching of hardwood pulps has led to the formation of chlorinated benzaldehydes and acetophenones as the major chlorinated phenols in the bleaching filtrates. Compounds identified in the filtrates include the chloro derivatives of vanillin, acetoguaiacone, syringaldehyde and acetosyringone. Thirteen of these compounds were converted to their acetates by in situ acetylation and were analysed by GC on a J&W DB5 capillary column. Chlorovanillins (2-chlorovanillin, 2,5- and 2,6-dichlorovanillin), chloroacetoguaiacones (2-, 5- and 6-chloroacetoguaiacone) and chloroacetosyringones (2-chloroacetosyringone and 2,6-dichloroacetosyringone) were positively identified as components of filtrates from bleaching of kraft pulps for the first time, along with the five other compounds tested. Satisfactory separation for all analytes was achieved except for 5-chloroacetoguaiacone and 2,5-dichlorovanillin, which co-eluted. Analysis of the latter compounds could be accomplished by mass detection with target ion monitoring. The DB5 column is thus useful for the analysis of the chlorinated benzaldehydes and acetophenones.

Conversion of dichlorovanillins to trichloroguaiacols - Components of pulp bleaching effluents

Keywonds Bleaching effluents Chlorination Chloroguaiacols Chlorovanillins NMR spectra Summary Reaction of 2-chlorovanillin with chlorine in acetic acid gave 2,5-dichIorovanillin, which on further chlorination yielded 3,4,6-trichloroguaiacoI, hitherto not described, by displacement of the formyl group. Analogously, both 5,6-dichlorovanillin and 2,6-dichloroisovanillin on chlorination afforded 4,5,6-trichloroguaiacol, together with tetrachloroguaiacol and the unreacted starting materials. NMR spectral data for all four trichloroguaiacol isomers are given, and the C NMR Signals are unequivocally assigned by analysis of fully coupled spectra.

An ubiquitous chlorohydropyrynone in filtrates from chlorine prebleaching of alkaline pulps

An abundant chlorinated compound was isolated from the neutral fraction of the extracts from filtrates from prebleaching alkaline pulps with chlorine. It formed acetate and methyl ether derivatives. The compound was identifled äs 4-chloro-3-hydroxy-2//-pyran-2-one on the basis of its NMR and mass spectra, and its structure was confirmed by synthesis from 3-hydroxy-2//-pyran-2-one by chlorination with yV-chlorosuccinimide. The compound in the prebleaching filtrates was analysed äs its methyl ether after extraction, methylation, and gas chromatography-mass spectrometry. It was found in C-stage filtrates from prebleaching of kraft and soda-AQ pulps from both eucalypt and Pinus radiata woods, but it was not initially present in filtrates from prebleaching with chlorine dioxide. The compound was generated on storage of both Cand D-stage filtrates under acidic conditions. It was found in the filtrates from bleaching oxygen-delignified alkaline pulps, but it was not present in the C-stage filtrates from bleaching eucalypt and pine bisulfite pulps, even after oxygen delignification. The compound was not present in filtrates from alkaline extraction of the prebleached pulps. A mechanism for the formation of the pyrone from 3-deoxypentonic acid end-groups of the hemicelluloses in the alkaline pulps is proposed.

Preparation of chlorosyringols and chloropyrogallols-components of pulp bleaching effluents

Abstract The preparation and properties of chlorosyringols and chloropyrogallols, components of pulp bleaching effluents, and their acetates are given. The compounds are obtained mainly by direct chlorination of both phenols or of syringol acetate with various chlorinating reagents. 5-Chloropyrogallol and 4,5-dichloropyrogallol were the products of demethylation of 5-chloro-3-methoxycatechol acetate and 4,5-dichloro-3-methoxycatechol acetate, respectively. The acetates of all ten chloro compounds were separated by gas chromatography. Electron impact mass spectra and 1 H and 13 C NMR data for the acetates are given.

Preparation and properties of chloro-3-methoxycatechols-components of pulp bleaching effluents

Abstract The preparation and properties are given for the seven chlorinated 3-methoxycatechols, several of which have been reported as components of pulp bleaching effluents. The 4- and 6-substituted compounds and the trichloro-3-methoxycatechol were obtained by direct chlorination of the parent catechol or its diacetate. The 5-substituted compound was prepared by the known addition of hydrochloric acid to 3-methoxy-ortho-benzoquinone, and further chlorination gave the 4,5- and 5,6-dichloro isomers. The diacetates of all seven compounds were separated by gas chromatography. Electron impact mass spectra and 1H and 13C NMR data for the diacetates are given.

Preparation and properties of chlorinated syringic acids, acetosyringones, acetoguaiacones and methoxy-p-hydroquinones — components of pulp bleaching effluents

A range of chlorinated phenols which serve as standards for compounds occurring in effluents from the bleaching of wood pulps with chlorine-containing reagents has been prepared. The chlorinated phenols include chlorosyringic acids, chloroacetosyringones, chloroacetoguaiacones, 5-chloro-2-methoxy-p-hydroquinone and chloro-2,6-dimethoxy-p-hydroquinones. With the exception of the ring-chlorinated acetoguaiacones which were prepared by reaction of chlorovanillin acetates with diazomethane, the compounds were obtained by direct chlorination of appropriate phenols or their acetates. Gas chromatographic and mass spectrometric data for the acetylated phenols are given.

Properties of chlorinated dihydroxybenzenes — Components of pulp bleaching effluents

Gas chromatography and mass spectrometry data are given for the acetates of the chlorodihydroxybenzenes which are components of wood pulp bleaching effluents and biologically-treated effluents, and are proposed intermediates in the chlorination of humic acids. The chlorohydroxybenzenes include the nine chlorocatechols, the six chlorohydroquinones and the seven known chlororesorcinols. The 22 chlorinated compounds were generally well separated on a phenyl methyl silicone column with the exception of three dichloro compounds. The chloro compounds with the same level of chlorine substitution were not able to be distinguished on the basis of their electron impact mass spectra.