Alkoxyl Substituents Research Articles

Evidence That Ceriporiopsis subvermispora Degrades Nonphenolic Lignin Structures by a One-Electron-Oxidation Mechanism

The white-rot fungus Ceriporiopsis subvermispora is able to degrade nonphenolic lignin structures but appears to lack lignin peroxidase (LiP), which is generally thought to be responsible for these reactions. It is well established that LiP-producing fungi such as Phanerochaete chrysosporium degrade nonphenolic lignin via one-electron oxidation of its aromatic moieties, but little is known about ligninolytic mechanisms in apparent nonproducers of LiP such as C. subvermispora. To address this question, C. subvermispora and P. chrysosporium were grown on cellulose blocks and given two high-molecular-weight, polyethylene glycol-linked model compounds that represent the major nonphenolic arylglycerol-(beta)-aryl ether structure of lignin. The model compounds were designed so that their cleavage via one-electron oxidation would leave diagnostic fragments attached to the polyethylene glycol. One model compound was labeled with (sup13)C at C(inf(alpha)) of its propyl side chain and carried ring alkoxyl substituents that favor C(inf(alpha))-C(inf(beta)) cleavage after one-electron oxidation. The other model compound was labeled with (sup13)C at C(inf(beta)) of its propyl side chain and carried ring alkoxyl substituents that favor C(inf(beta))-O-aryl cleavage after one-electron oxidation. To assess fungal degradation of the models, the high-molecular-weight metabolites derived from them were recovered from the cultures and analyzed by (sup13)C nuclear magnetic resonance spectrometry. The results showed that both C. subvermispora and P. chrysosporium degraded the models by routes indicative of one-electron oxidation. Therefore, the ligninolytic mechanisms of these two fungi are similar. C. subvermispora might use a cryptic LiP to catalyze these C(inf(alpha))-C(inf(beta)) and C(inf(beta))-O-aryl cleavage reactions, but the data are also consistent with the involvement of some other one-electron oxidant.

Phase Diagrams and Phase Transition Studies of a Homologous Series with Both Tilted and Orthogonal Hexatic Phases

Abstract Both smectic hexatic phases, Hex-B and Sm-F, were found m some three-ring 2-methylthlenyi derivatives terminated wth alkoxyl substituents. In a homologous series THI, the molecular terminal chains promote either tilted (for short chains) or orthogonal (for long chains) hexatic mesophases. For intermediate length chains (having 14 or 15 carbon atoms), the phase sequence is Hex-B - Sm-F - SmC - Sm-A. Thus phase sequence allows observation of two new triple points involving Hex-B phase. For some halogen substituted thienyl derivatives other mixed-tilt type phase sequence, Cry-G - Sm-F - Hex-B - Sm-A is found. Phase transitions involving hexatic phases were studied by DSC and X-ray scattering method.

Use of homologous series of analytes as mechanistic probes to investigate the origins of enantioselectivity on two chiral stationary phases

The normal-phase liquid chromatographic behavior of two homologous series of racemic carbamate derivatives of leucine anilides was examined on two chiral stationary phases, one of which has not been described heretofore. These chiral stationary phases are related structurally to the N-(3,5-dinitrobenzoyl)leucine chiral stationary phases originally developed in these laboratories, but differ from each other principally in the manner in which the chiral selector is attached to the silica gel support. While these selectors utilize the same interaction sites for bonding, the length of the analyte's linear alkoxyl substituent strongly influences enantioselectivity on only one of the chiral stationary phases. Similar but substantially less severe trends are noted as the length of a p-alkyl substituent on the second series of anilides is increased. Inferences concerning possible chiral recognition mechanisms are drawn from these observations.

Benzylamine antioxidants: relationship between structure, peroxyl radical scavenging, lipid peroxidation inhibition, and cytoprotection.

Three homologous series of 3,5-dialkoxy-4-hydroxybenzylamines were prepared and tested (1) as peroxyl radical scavengers in homogeneous aqueous solution, (2) as inhibitors of iron-dependent peroxidation of rabbit brain vesicular membrane lipids, and (3) as cytoprotective agents using primary cultures of rat hippocampal neurons exposed to hydrogen peroxide. The structural requirements for efficient radical trapping in homogeneous solution differed from those for effective lipid peroxidation inhibition: In homogeneous solution a kinetic preference existed for smaller, less sterically encumbered substituents flanking the reactive phenolic hydroxyl group. Lipid peroxidation inhibition, on the other hand, required longer more lipophilic substituents. Consequently, a lipophilic alkoxyl substituent at C3 and a small substituent at C5 appeared optimal for efficient radical scavenging activity in both lipid and homogeneous solution. Maximal cytoprotection of rat hippocampal neurons exposed to hydrogen peroxide was also associated with more lipophilic derivatives although substituent length and substituent bulk may represent independent parameters for relating structure and efficacy in this system.

A Facile Synthesis of 2-Aza-1,3-butadienes

Abstract 2-Aza-1,3-butadienes bearing alkoxyl substituent were obtained easily by the reaction of ketimines with orthoesters. The reaction proceeded smoothly by the addition of small amount of p-toluenesulfonic acid. When acetals were used in place of orthoesters, the corresponding 2-aza-1,3-butadienes were similarly prepared.

Liquid-crystalline quinoline derivatives

Abstract A number of novel liquid crystals have been synthesized. 2-Phenylquinolines with alkyl or alkoxyl substituents in positions 6 and 4′ show a texture typical of nematic mesophases and are characterized by a greater thermal stability than Schiff bases bearing the same substituents. The possibility of lowering the melting temperatures by means of eutectic mixtures is discussed.

The kinetics of radical polymerization of dialkyl esters of 3,4-dichloro-1,3-butadiene-2-phosphonic acid

The kinetics of the initial stage of radical polymerization of dialkyl esters of 3,4-dichloro-1,3-butadienyl-2-phosphonic acid have been studied, in mass and presence of DAK. It has been found that the polymerization rate of these monomers is described well by the usual equation, w= k [I] 0.5 [M]. It was shown that a change in size of the alkoxyl substituent on the phosphorus atom slightly affects the reactivity of these compounds. 3,4-Dichloro-1,3-butadiene-2-phosphonates are more active in polymerization than 1,3-alkadiene-1-phosphonates.

Partial Reduction of Dinitroarenes to Nitroanilines with Hydrazine Hydrate

Abstract Dinitroarenes containing substituents such as hydroxyl and amine groups could be conveniently reduced with 3 molar equivalents of hydrazine hydrate in presence of Raney nickel catalyst in ethanol/1,2-dichloroethane solvent mixture to give a product wherein one of the two nitro groups was reduced to the amino group. The yields of the partial reduction products are good. Under similar conditions alkoxyl substituents in the o,p-position to the nitro groups were displaced by the hydrazino group to give 2,4-dinitrophenylhydrazine as the main product. The details of the reduction reaction are described.

Substitution in cellulose ethers. Part II. Determination of the distribution of alkoxyl substituents on the glucose units using high-performance liquid chromatography

A procedure is described for the quantitative characterisation of the distribution of alkoxyl groups in methyl- and ethylcelluloses. The total hydrolysate is derivatised by reaction with benzoyl chloride in sodium hydroxide solution. Several favourable implications of pre-column derivatisation for the subsequent separation by high-performance liquid chromatography are discussed. Isocratic separations are carried out on LiChrosorb Si100, 10 µm, using chloroform with 0.1 and 0.2%V/V ethanol as the eluent. All eight individual glucose ethers present in the hydrolysates, including the positional isomers of alkyl- and dialkylglucoses, can be determined quantitatively from the chromatograms. Thus, the procedure provides data on the distribution of substituents according to their number and position in the anhydroglucose units.

The synthesis, structure and properties of 3,4-dichloro-1,3-butadiene-2-phosphonate polymers

The radical polymerization to large % conversion has been studied on 3,4-dichloro-1,3-butadiene-2-phosphonates (DCBP). The reactivity of the monomers has been established to increase with their electron-accepting capacity and reduction of the alkoxyl substituent size on the P-atom. The macromolecules have been found to contain only the 1,4-configuration chain units. Depending on the substituent present on the P-atom the polymers are solid and strong plastics or elastic rubber-like products.

Substituent Effect on a Photo-Smiles Rearrangement by Laser Photolysis

Abstract The photo-Smiles rearrangement was studied for two homologues of N-[2-(4-nitrophenoxy)ethyl]aniline by laser photolysis, an importance being attached to the effect of the alkoxyl substituent on the reactive position. The nitro group enhances the substitution at the para position, but the alkoxyl group does not play a significant role in the photosubstitution of the molecules.

Rearrangement of 2-hydroxyalkyl esters of diphenylthio- and selenophosphoric acids

Diphenylthio- and -selenophosphoric acids react with oxiranes to give 2-oxo-2-phenoxy-1,3,2-thiaor-selenaoxaphospholanes. Isopropylphenylthiophosphoric acid reacts with oxiranes to give a mixture of phosphorus-containing compounds, in which the thiaoxaphospho lanes with an alkoxyl substituent on the phosphorus atom predominate.

N-alkylation of aromatic amines with tris(trifluoroethyl)phosphate

Abstract Results of a study of the use of tris(trifluoroethyl)phosphate for the alkylation of aromatic amines are reported. Tris(trifluoroethyl)phosphate is a satisfactory reagent for introducing a trifluoroethyl group into aromatic amines, except for those containing N-alkyl, hydroxyl, or alkoxyl substituents and for those containing strongly electron-withdrawing groups such as nitro and carboxyl.

Soluble poly-1,2-bis-(3?-ethynyl-4?-alkoxyphenyl)ethanes

1. The insertion of alkoxyl substituents into the benzene rings of diacetylenes of the diphenylethane series leads to obtaining soluble and film-forming polyacetylenic oligomers. 2. The oligomers are typical dielectrics, but when subjected to thermal crosspolymerization they sharply increase their conductivity and become semiconductors.

Solvent effects on the conformations of ortho-substituted acetanilides

In acetanilides bearing nitro, halogen, alkoxyl, or carboxyl substituents in the ortho position, the intramolecular hydrogen bond is disrupted by polar solvents and the acetamido group adopts a position out of the plane of the aromatic ring. These changes are studied by means of changes in the deshielding effect of the amide carbonyl group on the remaining ortho proton.

Investigation of the sorption of the rare-earth elements and uranium by phosphorus-containing cation-exchange resins

1. The sorption capacity of a number of monofunctional phosphorus-containing cation-exchange resins based on polystyrenephosphoric acid with alkyl and alkoxyl substituents in the series of rare-earth elements was investigated. The distribution coefficients of the rare-earth elements (REE) on these resins were found for solutions of different acidities. 2. The investigated cation-exchange resins possessed substantial selectivity in the series of REE.

Conformational effects in compounds with six-membered rings—I : Synthesis of the stereoisomers of 5-alkylcyclo-hexane-1,3-dicarboxylic acids

Syntheses and proofs of configuration and conformation are described for stereoisomeric 5-alkylcyclohexane-1,3-dicarboxylic acids and their esters, in which the alkyl group varies in complexity from methyl to 1,1-diethylpropyl. A preparatively useful hydrogenolysis of alkoxyl substituents during Raney nickel hydrogenation is described.

Fluorescence spectra of some simple coumarins

The fluorescence spectra of six representative coumarins containing hydroxyl and/or alkoxyl substituents have been determined and compared on several commercial instruments. Measurements in methanol, dilute sulfuric acid, and dilute alkaline buffer permitted characterization of coumarin type, and observation of the change of fluorescent intensity with time allowed further refinement. Application of the method to paper chromatogram eluates, combined with an inherently high degree of sensitivity, should make it especially useful in the investigation of natural products.

Chemistry of polynuclear compounds. II. The behaviour in concentrated sulphuric acid solution and absorption spectra of some polynuclear quinones

In an investigation into the coking mechanism of coal, polynuclear quinones were adopted as models. The electronic absorption spectra of dibenzanthrone (I) ; 16,17-dimethoxydibenzanthrone (II) ; 16,17-diethoxydibenzanthrone (III) ; 16-methoxy-17-ethoxydibenzanthrone (IV) ; 16-methoxy-17-hydroxydibenzanthrone (V) ; and 16-ethoxy-17-hydroxydibenzanthrone (VI) in chlorobenzene and dioxane solution were measured and are discussed. Nan-planar configurations are proposed for II-VI and the possibility of the same for I considered. The electronic absorption spectra in concentrated sulphuric acid of I, II, V, and VI were measured and are discussed. IV, V, and VI are new vat dyes ; V is produced by the action of concentrated sulphuric acid on II and IV, and VI is produced by the same reaction with III. IV is prepared by the methylation of VI. The electronic absorption spectra of anthraquinone and some derivatives were measured in concentrated sulphuric acid and are discussed in conjunction with some of the above spectra. The infra-red spectra of IV, V, and VI confirm the identification of these compounds as 16,17-disubstituted dibenzanthrones and establish the nature of the alkoxyl substituents ; the quinonoid-carbonyl frequencies are discussed.