摘要:

A polymer-supported cellulose model was prepared by condensing the C-4′ hydroxyl group of a protected disaccharide, 2,3,6-tri-O-allyl-1,5-anhydro-4-O-(2,3,6-tri-O-allyl-ß-D-glucopyranosyl)-D-glucitol (5), with an iodomethylated polystyrene resin and removing the protecting groups. The preparation of5from cellobiose octaacetate (4) employed ten steps, utilizing allylate, acetate, and benzylidene protecting groups. The yield of5based on4was 5%.

ISSN:0277-3813    

DOI:10.1080/02773818808070695

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Three lignin model dimers have been synthesized. The models contain propyl alcohol appendages on C5 of ring A (12), C4 of ring B (15), and Cβ of the side chain (21), respectively. The propyl alcohol appendages will serve as “handles” for bonding the models to a polymer matrix. Model21has also been used to diagnostically examine the delignification efficiences of pulping chemicals.

ISSN:0277-3813    

DOI:10.1080/02773818808070696

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A unique lignin model dimer, 2-(2-methoxyphenoxy)-1-(3-methoxy-4-hydroxyphenyl)-1,5-pentanediol (8), was attached to a macroreticular polystyrene resin by means of a trityl ether linkage. The extent of model loading was determined by gravimetric analysis and Zeisel methoxyl content. When reacted under simulated kraft pulping conditions, the polymer model,8-TrP, afforded moderate yields of guaiacol, a fragmentation product. The addition of 29% ofp-dioxane or DMSO drastically depressed the yield of guaiacol from8-TrP.The polymer bound dimer model8-TrPand monomer model6-TrPwere relatively unstable to the harsh, simulated pulping conditions. Some or all of the observed guaiacol fragmentation product could have come from degradation of polymer-released model.

ISSN:0277-3813    

DOI:10.1080/02773818808070697

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

FTIR spectra of spruce, beech, and bamboo MWL's, representing G, GS and HGS lignins, were recorded and examined in the wavenumber range of 1800 to 700 cm−1. The spectra were then submitted to a mathematical self-deconvolution technique in order to resolve the intrinsically overlapped bands. The same procedure was carried out with the IR spectra from two G and two GS dehydrogenation polymers (DHP's) prepared by the “zutropf” (ZT) and “zulauf” (ZL) polymerization method. Thus, approx. 30 bands typical for lignins and lignin-like polymer models were detected in contrast to standard spectroscopic conditions, which render visible 15 to 17 broad bands. Hidden bands, usually visible as shoulders, came to light, i.e. the apparent resolution was increased considerably by deconvolution. The deconvolved spectra are standardized and depicted in the absorption mode together with the original spectra. The wavenumbers and intensities of 54 bands apparent after deconvolution are compiled in a Table to render possible a direct comparison of the IR characteristics of lignina and DHP's. A difference spectrum obtained by subtraction of a G ZT DHP spectrum from a spruce MWL spectrum illustratea the differences between these polymers.

ISSN:0277-3813    

DOI:10.1080/02773818808070698

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Catalytic hydroliquefaction of spruce wood particles (ca. 3 mm), suspended in a process derived slurry oil, has been conducted in a three 1-liter-capacity autoclave system using palladium on active charcoal in concentrations of 1 %, 0.5 % and 0.1 % (based on wood) and red mud (10 %) as a once-through catalyst. In a series of successive experiments the carrier slurry oil was separated from the net product oil (NPO) by trapping in a hot separator in order to recycle it. Decreasing Pd amounts increased viscosities of the carrier. In the presence of Pd, wood conversion rates of 95–97 % were obtained and yields of light-and middle distillate NPO decreased from 34 to 30 % when the amount of catalyst was reduced. The use of red mud gave NPO yields of 20 % and char yield increased to 37–43 %. In experiments with Pd, 4 % hydrogen and with red mud 1.7 % hydrogen (based on wood) was consumed.

ISSN:0277-3813    

DOI:10.1080/02773818808070699

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Aspen wood chips were treated with acidified chlorite to remove 90% of the lignin, or were extracted with concentrated alkali to remove 500 of the hemicellulose. Samples of the original chips, the resulting low-lignin aspenwood (LLA) and the low-hemicellulose aspenwood (LLA) were treated with saturated steam at 240°C for 20–180 s. Chemical analysis and enzymatic hydrolysis of the resulting water-washed substrates showed that, after 40 s of steaming, the rate and extent of enzymatic hydrolysis correlated better with removal of alkali-insoluble lignin than with removal of xylan. The original wood, LLA and LHA had similar crystallinity indices which increased in the water-insoluble fractions with time of steaming. Carbohydrate degradation products (“pseudo-lignin”) formed in equal amounts on steaming original wood or LLA, indicating furfural-lignin condensation to be not involved. Development of accessibility in LHA resembled that in original aspenwood, despite the absence of acetic acid for autohydrolysis.

ISSN:0277-3813    

DOI:10.1080/02773818808070700

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

From analyses of various samples of essential oils extracted by hydrodistillation from the branches ofThuja occidentalisL. andAbies Balsamea(L.) Mill., it was shown that there are extensive variations in the concentrations of the main components. The content in thujones and fenchone reaches a maximum value of 80 % after 40–50 minutes for cedarleaf oil. After 60 minutes, the concentrations in α-pinene and β-pinene in balsam fir oil are maximum at 15% and 40%, respectively.

ISSN:0277-3813    

DOI:10.1080/02773818808070701

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0277-3813    

DOI:10.1080/02773818808070694

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor