摘要:

Cellulose derivatives were produced from the cellulose fraction of pulp and paper mill sludge. The raw primary sludge was reacted under conventional cellulose derivatization conditions and the modified cellulose was isolated, in most cases, by dissolution in a suitable solvent. The cellulose derivatives produced were cellulose nitrate, cellulose acetate, carboxymethylcellulose, hydroxyethylcellulose, and methylcellulose. These compounds were characterized by Fourier transform infrared spectroscopy and carbon 13 nuclear magnetic resonance spectroscopy.

ISSN:0277-3813    

DOI:10.1080/02773818508085195

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The title compound (1, 1,5-anhydrocelloblitol) was degraded at 170°C in kraft pulping liquor (l. 01NaOH, 0.21Na2S) to determine whether the sulfur anions affect the rate-determining and/or product-determining steps of glycosldic bond cleavage. Since the extent of hydrolysis of S−2to form HS−and HO−was unknown,1was also degraded In NaOH solutions simulating total hydrolysis1.was NaOH, 1.4 ionic strength [μ]) and no hydrolysis (1.01NaOH, 1.6 μ). The proportion of glycosyl-oxygen bond cleavage (88%) and oxygenaglycon bond cleavage (12%) was the same in all three cases. The rate constant for degradation of1under the kraft conditions was equal to that for the NaOH control degradation simulating total hydrolysis of S−2, but greater than that for the control simulating no hydrolysis. This indicates that S−2is hydrolyzed under these kraft conditions to HS−and HO−, and that HS−does not participate in the rate-determining steps of glycosldic bond cleavage. Since HS−is a stronger nucleophile than HO−, these results also Imply that HO−does not cleave the glycosldic linkage by SN2 mechanisms. The yields of 1,6-anhydro-β-D-glucopyranose (1) from glycosyl-oxygen bond cleavage and 1,5-anhydro-D-glucitol (1) from oxygen-aglycon bond cleavage were lower for degradations of1in the kraft liquor than in the NaOH controls. This is due to HS−Involvement in the product-determining steps of the degradation of1.

ISSN:0277-3813    

DOI:10.1080/02773818508085196

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A modified pulping system of birch wood(Betula verrucosa / Betula pubesaena)involving alkaline pretreatment of the chips was studied as a possibility for a facilitated recovery of the carbohydrate degradation products (aliphatic acids). Although a proper pretreatment resulted in a fairly extensive formation of aliphatic acids compared with the lignin dissolution, delignification was retarded in the pulping stage (kraft or soda-anthraquinone) and the pulp yield was somewhat lower (0.5 – 1%of wood). Data are reported for the composition of aliphatic acids in liquors after pretreatments.

ISSN:0277-3813    

DOI:10.1080/02773818508085197

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Evidence has been gathered to demonstrate that coniferyl alcohol (CA) formation is predominantly a reaction of the initial phase of delignification. An attempt to link CA formation in the initial phase to the extent of delignification at the end of the cook indicated that the two processes were independent. Solutions of a commercial mixture of lignosulphonates also yielded CA when heated with alkali and catalysts like AQ. The relative effectiveness of certain redox catalysts to produce CA in this way correlates with their ability to accelerate the alkaline delignification of wood.

ISSN:0277-3813    

DOI:10.1080/02773818508085198

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The formation of methanol during treatment of wood meal with nitrogen dioxide is favored by the presence of oxygen and suppressed by addition of sodium sulfate. With 0.5% of added nitrogen dioxide large amounts of methanol were produced at 70°C when kraft lignin was impregnated with 0.5M nitric acid. A markedly increased formation of methanol and nitro groups in the lignin occurred when sodium nitrate was added. At low acidity the effect of sodium nitrate was insignificant. In a solution which was 0.5 molal with respect to nitric acid and 0.8 molal with respect to sodium nitrate, appreciable amounts of methanol and nitro groups were produced even when no nitrogen dioxide was added. This is explained by a generation of nitrogen dioxide from nitric acid in a autocatalytic process favored by high concentrations of nitrate and hydrogen ions.

ISSN:0277-3813    

DOI:10.1080/02773818508085199

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A Claisen-Schmidt type aldol addition reaction was used to synthesizeerythro- andthreo-ethyl-3-hydroxy-3-(4-benzyloxy-3-methoxyphenyl)-2-phenylpropanoate (la,lb) and erythro-2,3-bis(4-hydroxy-3-methoxyphenyl)-1,3-propanediol (9). The key aldol addition step was facilitated by adding a molar equivalent of Zn (II) cations to stabilize the addition product, thus inhibiting the reverse aldol reaction. This allowed the reaction to be carried out at moderate temperatures (-20 to 0°C) and rather short reaction times (10 to 20 minutes). The H-alpha–H-beta coupling constants in the PMR spectra were used for assignment of the stereoisomers.

ISSN:0277-3813    

DOI:10.1080/02773818508085200

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

One of the most important targets of current lignin chemistry is to visualize the inhomogeneities of lignin in the wood cell wall. The soft xylem fraction was separated from birch wood at the end of May, 1983. Cell walls of the soft xylem fraction were extremely thin and were mainly composed of compound middle lamella. Degradation products from the soft xylem by alkaline nitrobenzene oxidation and permanganate oxidation strongly indicated that compound middle lamella lignin in hardwood must be rich in guaiacyl units and highly condensed.

ISSN:0277-3813    

DOI:10.1080/02773818508085201

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The use of steam explosion as a pretreatment for woody biomass prior to enzymatic hydrolysis has been proposed in the past. In this study the effect of SO2 impregnation (1.6% SO2 on dry wood input) and H2SO4 impregnation (0.58% H2SO4 on dry wood input) on the exploded substrates produced are compared with the case where no acid was added. Both acid catalysts substantially improve the survival of pentose sugars when treatments of equal severity are compared. H2SO4 however reduces the extent to which lignin may be extracted from the water washed exploded substrates with caustic.

ISSN:0277-3813    

DOI:10.1080/02773818508085202

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0277-3813    

DOI:10.1080/02773818508085203

出版商:Taylor & Francis Group    

年代:1985

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:10.1080/02773818508085194

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor