STUDIES ON LIGNIN AND RELATED COMPOUNDS: XXII. FRACTIONATION OF METHANOL LIGNIN

1936 ◽  
Vol 14b (4) ◽  
pp. 115-119
Author(s):  
Jack Compton ◽  
Margaret Greig ◽  
Harold Hibbert
Keyword(s):  
Pure State ◽  
Soluble Fraction ◽  
Hydroxyl Groups ◽  
Related Compounds

Preparation of methanol lignin by the method of Brauns and Hibbert on a larger scale than that employed previously has disclosed the presence of a second fraction, soluble in ether-dioxane. The original methanol lignin and this new fraction are obtained in a pure state by fractionation with dioxane and benzene. The former has been shown to correspond to the methanol lignin from which the Brauns and Hibbert formula C42H32O6(OCH3)6(OH)4 was derived. The benzene-dioxane–soluble fraction has been methylated and acetylated, and shown to have a different composition, the ratio of methoxyl to hydroxyl groups being 5:3.

STUDIES ON LIGNIN AND RELATED COMPOUNDS: XXVII. METHYLATION AND STRUCTURE OF METHANOL LIGNIN (SPRUCE)

1937 ◽  
Vol 15b (1) ◽  
pp. 38-45 ◽  
Author(s):  
Jack Compton ◽  
Harold Hibbert
Keyword(s):  
Solvent Extraction ◽  
Sodium Hydroxide ◽  
Sulphuric Acid ◽  
Dimethyl Sulphate ◽  
Soluble Fraction ◽  
Anhydrous Methanol ◽  
Hydroxyl Groups ◽  
Slight Excess ◽  
Pure Methanol ◽  
Related Compounds

The composition of spruce methanol lignin prepared by the action of anhydrous methanol-hydrogen chloride on spruce meal was found to vary with the temperature and time of extraction. The reaction mixture contains two products, having methoxyl contents of 21.6 and 24%, respectively. Higher temperatures and longer time of heating favor formation of the latter. Long continued extraction of the crude methanol lignin with ether removed the second product (OCH3, 24%). This showed that this was a true "ether-soluble" fraction, but it was not found possible to isolate the pure methanol lignin (OCH3, 21.6%) by this process. The two substances can be separated either by solvent extraction or, as now shown, by use of 8–10% sodium hydroxide. Methylation of methanol lignin with dimethyl sulphate and alkali gives rise to the formation of new hydroxyl groups, the extent of the changes increasing markedly with rise in temperature of methylation and with increase in concentration of alkali used.A methanol lignin (OCH3, 22.3%) on repeated methylation yields a methylated lignin containing 37.2% methoxyl. Degradation during methylation is restricted by the use of acetone as solvent and only a slight excess of alkali (5–10%) at 20 °C. The results indicate the necessity for caution in the interpretation of data based on methylation experiments involving the use of alkali, and point to the presence of heterocyclic oxygen rings, non-furane in type, as part of the lignin structure. When refluxed for 48 hr. with 65 % aqueous methyl alcohol containing 9% sulphuric acid, ether-insoluble methanol lignin (OCH3, 22.3%) yielded a product with methoxyl content 21.3% which decreased to 20.9% when the product was treated for a further 52 hr.

scholarly journals New ent–Kaurane type Diterpene Glycoside, Pulicaroside-B, from Pulicaria Undulata L

2008 ◽  
Vol 3 (2) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Nasir Rasool ◽  
Viqar Uddin Ahmad ◽  
Naseem Shahzada ◽  
Muhammad A. Rashida ◽  
Aman Ullah ◽  
...  
Keyword(s):  
Spectral Data ◽  
Plant Extract ◽  
Soluble Fraction ◽  
2D Nmr ◽  
Spectroscopic Techniques ◽  
Spectral Evidence ◽  
Whole Plant ◽  
Derivatives Of ◽  
Related Compounds

Investigation of the n-butanol-soluble fraction of the whole plant extract of Pulicaria undulata yielded a new ent–kaurane type diterpene glycoside, pulicaroside-B (1), together with three known compounds, paniculoside-IV (2), roseoside (3), and corchoionol C (4). Compounds 3 and 4 are derivatives of α-ionol. The structures of the new and known compounds were elucidated by 1D- and 2D-NMR spectroscopic techniques, along with other spectral evidence, and by comparison of the spectral data with those of closely related compounds.

STUDIES ON LIGNIN AND RELATED COMPOUNDS: XXIX. A STUDY OF THE ACIDIC HYDROXYL GROUPS IN SPRUCE LIGNIN

1937 ◽  
Vol 15b (12) ◽  
pp. 532-535 ◽  
Author(s):  
R. G. D. Moore ◽  
George F. Wright ◽  
Harold Hibbert
Keyword(s):  
Phenolic Content ◽  
Hydriodic Acid ◽  
Hydroxyl Groups ◽  
Aromatic Content ◽  
Related Compounds

A demethylated spruce lignin suitable for further study has been obtained by treating methylated methanol lignin with hydriodic acid. This treatment removes the aliphatic hydroxyl, and leaves 6.9 aromatic and 0.6 carboxylic hydroxyl groups per kg. On the basis of the phenolic content it is estimated that the maximum aromatic content of spruce lignin is about 40 to 45%.

Lignin and related compounds. I. A comparative study of catalysts for lignin hydrogenolysis

1969 ◽  
Vol 47 (5) ◽  
pp. 723-727 ◽  
Author(s):  
J. M. Pepper ◽  
Y. W. Lee
Keyword(s):  
Comparative Study ◽  
Raney Nickel ◽  
Lignin Degradation ◽  
Soluble Fraction ◽  
Degradation Products ◽  
Quantitative Estimation ◽  
Liquid Chromatographic Separation ◽  
Lignin Degradation Products ◽  
Liquid Chromatographic ◽  
Related Compounds

A detailed comparative study has been made of the effectiveness of various catalysts for the hydrogenolysis of spruce wood lignin. The catalysts studied were Raney nickel, 10% palladium–charcoal, 5% rhodium–charcoal, 5% rhodium–alumina, 5% ruthenium–charcoal, and 5% ruthenium–alumina. Lignin degradation products were obtained initially as a chloroform-soluble fraction which was then divided and studied as diethyl ether-soluble and -insoluble fractions. Gas–liquid chromatographic separation of the ether-soluble fraction made possible the characterization and quantitative estimation of many of the lower molecular weight lignin degradation products.The data indicate that rhodium, palladium, and a limited amount of Raney nickel produce similar results as do ruthenium and an excess of Raney nickel; however, with the latter catalysts the degradation is more severe. In particular, rhodium–charcoal and palladium–charcoal appear to offer interesting advantages as catalysts for lignin hydrogenolysis.

STUDIES ON LIGNIN AND RELATED COMPOUNDS: XV. PHENOL GLYCOL LIGNIN

1935 ◽  
Vol 13b (1) ◽  
pp. 55-60
Author(s):  
Fritz Brauns ◽  
Harold Hibbert
Keyword(s):  
Condensation Product ◽  
Hydroxyl Groups ◽  
Nuclear Condensation ◽  
Condensation Products ◽  
Related Compounds

Phenol condensation products of glycol lignin, of a premethylated and a fully methylated glycol lignin have been prepared. In each case it has been found that, on the basis of the five methoxyl groups present in the original glycol lignin, three molecules of phenol react with one lignin unit by nuclear condensation, and when the product is worked up immediately no loss of methoxyl groups occurs. With the fully methylated glycol lignin in one experiment, some of the methoxyl groups were removed but the hydroxyl groups thus formed could not be remethylated with diazomethane, thus indicating their probable aliphatic character. Quercetin does not give a phenol condensation product under the same conditions.

Kinetic Study on the Esterification of Hexanoic Acid with N,N-Dialkylamino Alcohols: Evidence for an Activation by Hydrogen Bonding

2006 ◽  
Vol 61 (5) ◽  
pp. 583-588 ◽  
Author(s):  
Stefan Breitenlechner ◽  
Thorsten Bach
Keyword(s):  
Hydrogen Bonding ◽  
Rate Increase ◽  
Order Rate Constant ◽  
Hexanoic Acid ◽  
Hydroxyl Groups ◽  
First Order ◽  
Moderate Rate ◽  
Pseudo First Order ◽  
Related Compounds ◽  
Membered Transition State

The pseudo-first order rate constant for the esterification of hexanoic acid (1) and five different N,N-dialkylamino alcohols (2) was determined in comparison to 1-hexanol (k = 0.67 · 10−5 s−1). The values range from 0.60 · 10−5 s−1 to 9.3 · 10−5 s−1. The data suggest a differing reactivity for structurally related compounds, which is directly correlated to the ability of the corresponding amino alcohol to activate the carboxylic acid by hydrogen bonding. A seven-membered transition state C≠ is postulated for reactions of 2-amino alcohols. The fastest reaction was observed for trans-2-(N,N-dimethylamino) cyclohexanol (2e), in which the amino and the hydroxyl groups are in an almost perfect synperiplanar 1,2-position. Attempts to further enhance the rate of the esterification by the addition of potential catalysts failed. Only Cu(OTf)2 (2.5 mol-%) allowed for a moderate rate increase from 7.5 · 10−5 s−1 (uncatalyzed) to 14.8 · 10−5 s−1 (catalyzed) in the esterification of hexanoic acid (1) with 2-(N,N-dimethylamino)ethanol (2a).

STUDIES ON LIGNIN AND RELATED COMPOUNDS: IX. ETHERS OF GLYCOL-LIGNIN

1931 ◽  
Vol 5 (3) ◽  
pp. 302-305
Author(s):  
Harold Hibbert ◽  
Léo Marion
Keyword(s):  
Sodium Hydroxide ◽  
Sodium Salt ◽  
Aqueous Sodium Hydroxide ◽  
Hydroxyl Groups ◽  
Acidic Properties ◽  
Aqueous Sodium ◽  
Spruce Wood ◽  
Free Hydroxyl ◽  
Chloro Derivatives ◽  
Related Compounds

Glycol-lignin prepared from spruce wood has been found to form a sodium salt which reacts with chloro-derivatives, giving rise to the corresponding glycol-lignin ethers. These compounds are insoluble in aqueous sodium hydroxide but still contain free hydroxyl groups which can be methylated without the ethereal linkage being broken. Hence glycol-lignin contains several free hydroxyl groups, one or more of which possess acidic properties. Both the methoxymethyl ether and the 2:4-dinitrophenyl ether of glycol-lignin have been prepared. The evidence would seem to indicate the presence of both phenolic and aliphatic hydroxyl groups.

scholarly journals SIGNIFICANCE OF THE HYDROXYL GROUPS OF STEROIDS IN PROMOTING GROWTH

1954 ◽  
Vol 100 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Charles Huggins ◽  
Elwood V. Jensen
Keyword(s):  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Critical Importance ◽  
Hydrogen Atoms ◽  
Albino Rat ◽  
Ketone Group ◽  
Related Compounds

The presence of a 17ß-hydroxyl group endows the simple androstane molecule with the ability to produce growth of the uterus, vagina, and prostate of the female hypophysectomized albino rat. It appears that hydrogen atoms at position 17 are of critical importance since related compounds with a ketone group at this site are inactive. Monofunctional steroids with a hydroxyl or a ketone group at position 3 likewise are devoid of activity. If a phenolic A-ring is present in monofunctional steroids the 17ß-hydroxyl group is not obligatory for growth. Proliferation of the uterus and vagina were found to follow the administration of 17-desoxyestradiol.

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