Studies on the Lignin of Eucalyptus regnans F. Muell. V. Ethanol Lignin

1953 ◽  
Vol 6 (1) ◽  
pp. 44
Author(s):  
JWT Merewether
Keyword(s):  
Molecular Weight ◽  
Acetic Anhydride ◽  
Hydrogen Chloride ◽  
Benzoyl Chloride ◽  
Aqueous Alkali ◽  
Carbonyl Groups ◽  
Equivalent Weight ◽  
Eucalyptus Regnans

Lignin has been isolated from Eucalyptus regnans F. Muell. by refluxing with ethanolic hydrogen chloride, and the product separated into an ether-insoluble ethanol lignin-A and an ether-soluble ethanol lignin-B. Ethanol lignin-A has an equivalent weight of 1400 and, on the assumption that the molecular weight is of this order, contains two ethoxyl and nine methoxyl groups. Acetic anhydride and benzoyl chloride in pyridine yield respectively a hepta-acetate and heptabenzoate, while benzoyl chloride in aqueous alkali yields a pentabenzoate. Diazomethane yields a dimethyl derivative which gives a penta-acetate on acetylation. Schotten-Baumann benzoylation of this dimethyl derivative yields a dibenzoate. Two carbonyl groups are present, as shorn by the formation of a bisphenylhydrazone and a bis-p-nitrophenylhydrazone. The data are consistent with the formula C59H38O10(OC2H5)2(OCH3)9(OH)7.

Studies on the Lignin of Eucalyptus regnans. III. The Isolation of an Alkali Lignin from Sulphate Pulping

1949 ◽  
Vol 2 (1) ◽  
pp. 117
Author(s):  
JWT Merewether
Keyword(s):  
Acetic Anhydride ◽  
Alkaline Hydrolysis ◽  
Empirical Formula ◽  
Benzoyl Chloride ◽  
Dimethyl Sulphate ◽  
Hydroxyl Groups ◽  
Equivalent Weight ◽  
Eucalyptus Regnans ◽  
Alkali Lignin ◽  
Hydrolysis Of

An alkali lignin containing no sulphur has been obtained as a by-product from the sulphate pulping of Eucalyptus regnans. Like other alkali lignins it contains hydroxyl groups, both acidic and alcoholic, as well as methoxyl groups. Acetic anhydride in pyridine yields an octoacetyl derivative which is readily hydrolysed by boiling water to a heptacetyl derivative. In pyridine, benzoyl chloride yields an octobenzoyl derivative while in aqueous alkali it yields a hexabenzoyl compound. Dimethyl sulphate yields a heptamethyl alkali lignin, diazomethane a hexamethyl derivative, while cold alkaline hydrolysis of the latter gives a pentamethyl derivative, and hot alkaline hydrolysis yields an anhydrotrimethyl alkali lignin. One of the methoxyl groups formed by methylation is unstable to acetylation by acetic anhydride in pyridine, heptamethyl alkali lignin yielding a hexamethyldiacetyl derivative, hexamethyl alkali lignin a pentamethyltriacetyl derivative, pentamethyl alkali lignin a tetramethyltetracetyl derivative, and anhydrotrimethyl alkali lignin the corresponding anhydrodimethyltetracetyl alkali lignin. Triphenylchloromethane in pyridine yields a monotrityl derivative.p-Nitrophenylhydrazine gives a di-p-nitrophenylhydrazone and phenylhydrazine a phenylhydrazone-osazone. Potentiometric titration shows two points of inflection and an equivalent weight of 863. The data are consistent with the empirical formula C92Hl04O34(1754) or C73H54O9,(OCH3)14,(OH)3,C(OH),CO-CH20H,C0,COOH

Studies on the Lignin of Eucalyptus regnans. II. The Nature of the Hydroxyl Groups and the Presence of the Carbonyl Group in Thiolignin

1948 ◽  
Vol 1 (2) ◽  
pp. 241
Author(s):  
JWT Merewether
Keyword(s):  
Benzoyl Chloride ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Carbonyl Groups ◽  
Eucalyptus Regnans ◽  
Trimethyl Ether ◽  
Free Hydroxyl ◽  
Active Methylene ◽  
Methylene Group ◽  
Alcoholic Hydroxyl

E. regnans thiolignin reacts with p-toluenesulphonyl chloride in pyridine to form a hexatosyl derivative ; its trimethyl ether reacts likewise to form a tritosyl derivative. Both compounds still have a free hydroxyl group which can be acetylated. Similarly they yield a hexabenzoate and tribenzoate respectively by the Schotten-Baumann reaction, but in pyridine, thiolignin reacts with benzoyl chloride to give a heptabenzoate and trimethylthiolignin a tetrabenzoate. No reaction takes place when trimethyl thiolignin is treated with triphenylchloromethane in pyridine. The above data are interpreted as evidence that of the four alcoholic hydroxyl groups three are secondary and one tertiary. With phenylhydrazine, thiolignin yields a phenylosazone ; with p-nitrophenylhydrazine it yields a p-nitrophenylhydrazone. On the other hand, trimethylthiolignin does not react with phenylhydrazine, indicating the absence of non-enolizable carbonyl groups. Thiolignin condenses with benzaldehydes indicating the presence of an active methylene group. From this evidence it is deduced that the grouping CH2-CO-CHOH- is present.

Chemical Depolymerisation of Natural Rubber in Biphasic Medium

2014 ◽  
Vol 1024 ◽  
pp. 193-196
Author(s):  
Ibrahim Suhawati ◽  
Asrul Mustafa
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Chemical Structure ◽  
Inner Core ◽  
Particle Surface ◽  
Natural Rubber Latex ◽  
Carbonyl Groups ◽  
Latex Particles ◽  
Liquid Natural Rubber ◽  
Biphasic Medium

The molecular weight of natural rubber (NR) can be reduced via depolymerization reaction to produce liquid natural rubber (LNR) with a molecular weight less than 50 000 g/mol. In the reaction, hydrogen peroxide and sodium nitrite were added to natural rubber latex to initiate a redox type reaction which then breaks the NR chain. Low permeation of reagents into latex particles allows the degradation to occur greater at the latex particle surface relative to the inner core contributes to high molecular weight distribution (MWD) or polydispersity of the LNR obtained. In this recent works, the reaction was carried out in a biphasic medium consisting of water and toluene phases. Toluene swells latex particles as indicated by the SEM micrographs showing changes in the size of latex particles. This occurrence is suggested to increase the influx of reagents into the latex particles. Consequently, with higher permeation of reagents into the latex particles resulted in the decrease of molecular weight and lower polydispersity of the LNR obtained. Chemical structure analysize showed that the LNRs obtained were attached with hydroxyl and carbonyl groups.

Jack bean urease (EC 3.5.1.5). IV. The molecular size and the mechanism of inhibition by hydroxamic acids. Spectrophotometric titration of enzymes with reversible inhibitors

1980 ◽  
Vol 58 (12) ◽  
pp. 1323-1334 ◽  
Author(s):  
Nicholas E. Dixon ◽  
John A. Hinds ◽  
Ann K. Fihelly ◽  
Carlo Gazzola ◽  
Donald J. Winzor ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Active Site ◽  
Binding Sites ◽  
Spectrophotometric Titration ◽  
Hydroxamic Acids ◽  
Jack Bean Urease ◽  
Equivalent Weight ◽  
Guanidinium Chloride ◽  
Jack Bean ◽  
Equilibrium Ultracentrifugation

Kinetic, spectral, and other studies establish that hydroxamic acids bind reversibly to active-site nickel ion in jack bean urease. Equilibrium ultracentrifugation studies establish that the molecular weight of native urease is 590 000 ± 30 000 while that of the subunit formed in 6 M guanidinium chloride in the presence of β-mercaptoethanol is ~95 000. Essentially the same subunit molecular weight (~93 000) is found by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, subsequent to denaturation in a guanidinium chloride – β-mercaptoethanol system at various temperatures. Coupled with an equivalent weight of 96 600 for binding of the inhibitors acetohydroxamic acid and phosphoramidate, these results establish securely that urease is a hexamer with one active site per 96 600-dalton subunit. Consistent values for the equivalent weight are obtained by a routine spectrophotometric titration of the active site of freshly prepared urease with trans-cinnamoylhydroxamic acid. General equations are derived which describe spectrophotometric titrations of binding sites of any enzyme with a reversible inhibitor. These equations allow the evaluation of the difference spectrum of the protein–inhibitor complex even when the binding sites cannot readily be saturated with the inhibitor or vice versa.

α-(4-Tolyl)dopamine, derivatives and analogues; Synthesis and pharmacological screening

1983 ◽  
Vol 48 (5) ◽  
pp. 1447-1464 ◽  
Author(s):  
Vladimír Valenta ◽  
Jiří Holubek ◽  
Emil Svátek ◽  
Antonín Dlabač ◽  
Marie Bartošová ◽  
...  
Keyword(s):  
Acetic Anhydride ◽  
Hydrobromic Acid ◽  
Benzoyl Chloride ◽  
Substitution Reactions ◽  
Low Degree ◽  
Anticataleptic Activity ◽  
Pharmacological Screening ◽  
Higher Doses ◽  
Hydroxyethyl Piperazine ◽  
Antiarrhythmic Effects

The ketone XIII, obtained by Friedel-Crafts reaction of toluene with homoveratroyl chloride, was converted by the Leuckart reaction to the formamido derivative IXb which was used as the starting product for the synthesis of amines IIIb-Vb. Reduction of the ketone XIII gave the alcohol XVI which was treated with hydrogen chloride and afforded the chloro compound XVII. Its substitution reactions with 1-methylpiperazine, 1-(2-hydroxyethyl)piperazine and 1-phenylpiperazine resulted in the piperazines VIb-VIIIb. Acylations of the amine IIIb with acetic anhydride and homoveratroyl chloride gave the amides Xb and XIb which, together with the formamide IXb, were subjected to the Bischler-Napieralski reaction. 3,4-Dihydroisoquinolines XXII-XXIV were obtained and reduced to the 1,2,3,4-tetrahydroisoquinolines XXVb-XXVIIb. Treatment of XXVIIb with formaldehyde afforded the berbine derivative XXVIII. Demethylation of the amine IIIb with hydrobromic acid resulted in the title compound IIIa. Similar demethylations of the dimethoxyamines IVb-VIIIb, XXVb and XXVIb led to the dihydroxyamines IVa-VIIIa, XXVa and XXVIa which are dopamine derivatives. Reaction of Va with benzoyl chloride gave the dibenzoate XXX. The CNS activities of the compounds prepared are of a low degree. Several of them (IIIa-VIa, IIIb-Vb, XXVb) show in higher doses signs of central stimulant action but only for compound IVa an antireserpine effect was proven. The expected anticataleptic activity was found only in a low degree with compound VIIIa; on the contrary, compounds IIIa and XXVa are procataleptogenic. Some compounds (IIIa, IXb, XXVIa, XXVIII) potentiated thiopental. In single cases local anaesthetic, spasmolytic, hypotensive, hypertensive, hypoglycaemic, diuretic and antiarrhythmic effects were observed.

ipso Nitration. XXVII. The crystal structure and stereochemistry of 3-bromo-6-methyl-6-nitrocyclohexa-2,4-dienyl acetate, 5-bromo-2-methyl-6-nitrocyclohexa-2,4-dienyl acetate, and 3-bromo-6-methyl-6-nitrocyclohexa-2,4-dienyl chloride

1986 ◽  
Vol 64 (12) ◽  
pp. 2382-2387 ◽  
Author(s):  
Gordon W. Bushnell ◽  
Alfred Fischer ◽  
George N. Henderson ◽  
Sumit Ray Mahasay
Keyword(s):  
Crystal Structure ◽  
Acetic Anhydride ◽  
Crystal Structures ◽  
Hydrogen Chloride ◽  
Rearrangement Product

The adduct obtained on nitration of 4-bromotoluene in acetic anhydride is (Z)-3-bromo-6-methyl-6-nitrocyclohexa-2,4-dienyl acetate. Its stereoselective rearrangement product, obtained on thermolysis in the presence of p-cresol, is (Z)-5-bromo-2-methyl-6-nitrocyclohexa-2,4-dienyl acetate. Reaction with hydrogen chloride in ether is also stereospecific and gives (Z)-3-bromo-6-methyl-6-nitrocyclohexa-2,4-dienyl chloride. The crystal structures of these compounds are reported.

scholarly journals Keggin-Type Heteropolyacid for Ring-Opening Polymerization of Cyclohexene Oxide: Molecular Weight Control

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Ahmed Aouissi ◽  
Zeid Abdullah Al-Othman ◽  
Abdurrahman Salhabi
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
Acetic Anhydride ◽  
Ring Opening ◽  
Weight Control ◽  
Reaction Medium ◽  
Resonance Spectroscopy ◽  
Cyclohexene Oxide ◽  
Scanning Calorimetry ◽  
Catalyst Amount

Polymerization of 1,2-cyclohexene oxide (CHO) in dichloromethane was catalyzed by 12-tungstophosphoric acid (H3PW12O40·13H2O) as a super solid acid. The effect of polymerization parameters such as reaction time, temperature, and catalyst amount was investigated. The effect of acetic anhydride as a ring-opening agent was also investigated. The resulting poly(1,2-cyclohexene oxide) (PCHO) was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy (1HNMR), gel-permeation chromatography (GPC), and differential scanning calorimetry (DSC). It has been found that the PCHO prepared over H3PW12O40·13H2O has a stereoregularity higher than that prepared over clay and Aluminium alkoxide catalysts. TheTgvalue obtained is due to the microstructure but not to molecular weight. The yield and the molecular weight of the polymer depend strongly on the reaction conditions. Molecular weights can be readily controlled by changing reaction temperature, reaction time, and catalyst amount. Contrary to most polymerization reactions, the molecular weight increases with the temperature increase. Addition of acetic anhydride to the reaction medium increased the yield threefold.

scholarly journals Enaminonitrile as Building Block in Heterocyclic Synthesis: Synthesis of Novel 4H-Furo[2,3-d][1,3]oxazin-4-one and Furo[2,3-d]pyrimidin-4(3H)-one Derivatives

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Manal M. El-Shahawi ◽  
Ahmed K. El-Ziaty
Keyword(s):  
Acetic Anhydride ◽  
Building Block ◽  
Benzoyl Chloride ◽  
Heterocyclic Synthesis ◽  
Elemental Analyses ◽  
Nitrogen Nucleophiles

2-Amino-4,5-diphenylfuran-3-carbonitrile 1 was utilized as building block for the construction of new furo[2,3-d]pyrimidin-4(3H)-one derivative 2 and 4H-furo[2,3-d][1,3]oxazin-4-one derivative 3 via treatment with acetic anhydride and benzoyl chloride, respectively. The 4H-furo[2,3-d][1,3]oxazin-4-one derivative 3 was transformed into novel furo[2,3-d]pyrimidin-4(3H)-ones 4–8, tetrazolylfuran derivative 10, and furo[3,2-d]imadazolone derivative 11 via reaction with various nitrogen nucleophiles. The structure features of the synthesized compounds were established from their spectral and elemental analyses.

Proton Modification of Ultra High Molecular Weight Polyethylene to Promote Crosslinking for Enhanced Chemical and Physical Properties

1995 ◽  
Vol 396 ◽  
Author(s):  
J.F. Wilson ◽  
J.R. Liu ◽  
F. Romero-Borja ◽  
W.K. Chu
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Surface Region ◽  
Low Doses ◽  
Carbonyl Groups ◽  
Hydrogen Annealing ◽  
Near Surface ◽  
Gel Permeation ◽  
Ultra High Molecular Weight

AbstractCrosslinking onset was investigated for ultra high molecular weight polyethylene(UHMW-PE) implanted with 2.6 MeV H+ ions at low doses from 6×1011-3×1013 ions/cm2. Crosslinking in the near surface region(20–40μm) was determined from gel permeation chromatography(GPC) of 1,2,4 trichlorobenzene sol fractions and increased with dose. Fourier transform infrared spectroscopy(FTIR) showed irradiation resulted in increased free radicals confirmed from increased carbonyl groups. Hydrogen annealing after ion implantation resulted in 38–49% decrease in FTIR peak associated with carbonyl.

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