Showing papers on "Methanol published in 1977"

A method for determination of tannins in foods by means of immobilized protein

Abstract: Immobilized bovine serum albumin (BSA) binds tannins selectively at pH 4. Monomeric polyphenolic substances such as gallic acid, chlorogenic acid and catechol do not interact with the protein under these conditions. The protein-tannin complexes are dissociated by organic solvents such as methanol or dimethylformamide and the released tannins may be recovered in pure form. These principles have been utilized in the design of an analytical method which utilizes small columns of Sepharose-BSA to achieve separation between the two groups of compounds.

Purification and properties of the methane mono-oxygenase enzyme system from Methylosinus trichosporium OB3b.

Abstract: 1. A three-component enzyme system that catalyses the oxidation of methane to methanol has been highly purified from Methylosinus trichosporium. 2. The components are (i) a soluble CO-binding cytochrome c, (ii) a copper-containing protein and (iii) a small protein; the mol. wts. are 13 000, 47 000 and 9400 respectively. The cytochrome component cannot be replaced by similar cytochrome purified from Pseudomonas extorquens or by horse heart cytochrome c. 3. The stoicheiometry suggests a mono-oxygenase mechanism and the specific activity with methane as substrate is 6 micronmol/min per mg of protein. 4. Other substrates rapidly oxidized are ethane, n-propane, n-butane and CO. Dimethyl ether is not a substrate. 5. The purified enzyme system utilizes ascorbate or, in the presence of partially purified M. trichosporium methanol dehydrogenase, methanol as electron donor but not NADH or NADPH. 6. Activity is highly sensitive to low concentrations of a variety of chelating agents, cyanide, 2-mercaptoethanol and dithiothreitol. 7. Activity is highly pH-dependent (optimum 6.9-7.0) and no component of the enzyme is stable to freezing. 8. The soluble CO-binding cytochrome c shows oxidase acitivity and the relationship between this and the oxygenase activity is discussed.

Methanol poisoning. V. Role of formate metabolism in the monkey.

Abstract: The accumulation of formic acid is an important factor in the production of the metabolic acidosis after methanol administration to the monkey. Formic acid accumulation following methanol administration does not occur in the rat, which oxidizes formate at rates that are markedly higher than those seen in the untreated monkey. The objectives of this study were to determine the pathway responsible for formate oxidation in the monkey and to compare the disposition of formate in the monkey with that of the rat. This information was used to increase and decrease the rate of accumulation of formate in the monkey and to increase or decrease the sensitivity of the monkey to methanol poisoning. Results show that a folate-de-pendent pathway is the major route of formate metabolism in the monkey as has been shown previously in the rat. Folate administration to the monkey increases formate oxidation. 4-Methylpyrazole treatment, after the production of metabolic acidosis and formic acidemia in the monkey, reverses the acidotic state and formic acidemia. Although the folate-deficient monkey is the most sensitive animal towards methanol poisoning, formaldehyde did not appear in the blood, body fluids, or tissues. Since formaldehyde does not accumulate in the presence of high methanol and high formate, and since reversal of formate accumulation leads to reversal of the features of the methanol poisoning syndrome, it is suggested that formate rather than formaldehyde is the major determinant of methanol poisoning in monkeys and probably in man.

Kinetics of the pyrolysis of methanol

Abstract: An adiabatic turbulent flow reactor was used to examine the pyrolysis of methanol in the temperature range 1070-1225 K at atmospheric pressure. Emphasis has been placed on determining the important initiation and termination steps and estimating rate constants for several reactions. A steady state treatment of the proposed 19-step mechanism yields a complex rate law for methanol decay. The roles of hydrogen as a promoter and methane as an inhibiter are accounted for in the proposed mechanism.

Surface reactivity of zeolites type H-Y and Na-Y with methanol

Abstract: The surface reactions of methanol with zeolites type H-Y and Na-Y, between 20 and 350°C, were studied by infrared spectroscopy, gas liquid chromatography, adsorption isotherms and thermo-gravimetric techniques.At room temperature methanol is physically adsorbed on both zeolites. In the case of zeolite H-Y the adsorption occurs via hydrogen bonds between the OH-groups of the methanol molecules and the surface hydroxyl groups and the structural oxygen atoms of the zeolite. At 20°C, a part of the surface hydroxyl groups reacts with the methanol molecules, initiating the methoxylation of the surface, according to the scheme Si—OH + CH3OH →SiOCH3+ H2O. This esterification of the silanol groups is enhanced as the temperature increases, and reaches a maximum at ∼130°C. Above 120°C a new reaction of the surface methoxyl groups with methanol occurs, with formation of dimethylether. The production of dimethylether reaches its maximum at 210°C. Around 250°C, secondary reactions forming gaseous cracking products, predominantly butane and propene, were detected. In the temperature range studied no chemical reaction of methanol with the surface of the dehydrated Na-Y was observed. Therefore, it is concluded that the surface activity of the zeolite H-Y in dehydration of methanol is mainly due to the high Bronsted acidic character of its surface. The analysis of the methoxylation reaction in terms of surface diffusion of the methanol molecules, and of the proton exchange frequency between adsorbed methanol molecules and the zeolite surface, shows that the lifetime of the protonated CH3OH+2 molecule is the rate controlling factor of the methoxylation process.

Selective formation of ethanol from methanol, hydrogen and carbon monoxide

Abstract: A process for the selective formation of ethanol which comprises contacting methanol, hydrogen and carbon monoxide with a catalyst system comprising cobalt acetylacetonate, a tertiary organo Group V A compound of the periodic Table, a first promoter comprising an iodine compound and a second promoter comprising a ruthenium compound.

Methanol conversion to para-xylene using a zeolite catalyst containing an oxide of boron, magnesium, phosphorus, or mixtures

Abstract: A catalytic process is provided for converting lower monohydric alcohols and their ethers, especially methanol and dimethyl ethers, to a hydrocarbon mixture rich in C 2 -C 3 olefins and mononuclear aromatics with high selectivity for para-xylene production by contact, under conversion conditions, with a catalyst comprising a crystalline aluminosilicate zeolite, said zeolite having a silica to alumina ratio of at least about 12 and a constraint index, as hereinafter defined, within the approximate range of 1 to 12, said catalyst having been modified by the addition thereto of a minor proportion of an oxide of boron or magnesium either alone or in combination, or in further combination with an oxide of phosphorus.

Silica-modified zeolite catalysts

Abstract: An improved method is provided for the production of silica-modified zeolite catalysts. Such catalysts are especially useful in a wide variety of processes including the conversion of methanol to gasoline, methanol to olefins, selective toluene disproportionation, toluene alkylation with methanol, the synthesis of p-ethyl toluene, lubricant hydro-dewaxing and the like. The catalysts formed in accordance with the present invention comprise crystalline aluminosilicate zeolites having a silica to alumina ratio of at least about 12, a constraint index, as hereinafter defined, within an approximate range of 1-12 and having contained within the interior crystalline structure thereof added amorphous silica in an amount of at least about 0.3% and preferably between about 0.5% and about 30 weight percent. The resultant catalyst is characterized by an n-hexane sorption capacity at a temperature of 90° C. and an n-hexane partial pressure of 83 mm. of mercury which is at least 1 percent less than corresponding sorption capacity under identical conditions for the unmodified zeolite. Generally, the n-hexane sorption capacity for the described silica-modified zeolite, at the above specified conditions, is 5 to 60 percent less than that for the zeolite which has not undergone treatment to incorporate amorphous silica therein. The invention described herein also encompasses synthesis of the specified catalyst and use of the same in, for example, selectively converting lower monohydric alcohols and their ethers, especially methanol and dimethyl ether, to a hydrocarbon mixture rich in ethylene and propylene.

Methyleneketenes and methylenecarbenes. VII. Evidence for the pyrolytic generation of methyleneketene (propadienone)

Abstract: Oxidation of 2,2,5-trimethyl-5-phenylseleno-1,3-dioxan-4,6-dione with m-chloroperbenzoic acid in methylene chloride gives a solution containing 2,2-dimethylspiro[1,3-dioxan-5,2'-oxiran]-4,6-dione and the unstable 2,2-dimethyl-5-methylene-1,3-dioxan-4,6-dione, which forms stable adducts with cyclohexadiene and cyclopentadiene. Flash vacuum pyrolysis of the cyclopentadiene adduct over the temperature range 460- 570° and detection of the components present in the pyrolysate by mass spectrometry showed that cyclopentadiene, acetone, carbon dioxide and methyleneketene (CH2=C=C=O) are formed; the last breaks down into acetylene and carbon monoxide at higher temperatures (520-570°). Infrared measurements on the pyrolysis products kept at liquid nitrogen temperature showed absorption near 2100 cm-1 which is attributed to methyleneketene. Reaction of the pyrolysate with aniline vapour or methanol vapour yielded acrylanilide and methyl acrylate respectively. Pyrolysis in the absence of trapping agents gave a glassy solid on an uncooled glass surface. This solid is considered to be formed by addition of methyleneketene to 2,2-dimethyl-5-methylene-1,3-dioxan-4,6- dione. Methanolysis of the solid and esterification with diazomethane gave dimethyl 2-methoxycarbonyl-4-methylenepentanedioate.

Immobilization of yeast microbodies by inclusion with photo-crosslinkable resins.

Abstract: Yeast microbodies containing FAD-dependent alcohol oxidase, catalase and D-amino acid oxidase were isolated from methanol-grown cells of Kloeckera sp. 2201 and immobilized intact in matrices formed by a short-time illumination of photo-crosslinkable resin oligomers. The relative activities of catalase, alcohol oxidase and D-amino acid oxidase of the gel-entrapped microbodies were 36, 76 and 31% respectively as compared with those of free microbodies. Immobilization enhance d the stability of catalase to a certain degree, but not that of alcohol oxidase. The pH/activity profiles of catalase and alcohol oxidase of the entrapped organelles showed more narrow pH optima than those of the free counterparts. D-Amino acid oxidase in immobilized microbodies showed a somewhat higher Km value for D-alanine than that in free ones. Immobilized microbodies oxidized two moles of methanol to form two moles of formaldehyde with consumption of one mole of molecular oxygen. Addition of 3-amino-1,2,4-triazole, an inhibitor of catalase, reduced the formation of formaldehyde to half the amount without change in the amount of oxygen consumed, indicating the synergic action of alcohol oxidase and catalase in methanol oxidation in the microbodies of living yeast cells.

NMR-spectroscopic studies on solvent electrophilic properties, Part II: Binary aqueous-non aqueous solvent systems

Abstract: Acceptor numbers have been determined for binary mixtures of water with acetonitrile (AN), dioxane, acetone (AC), pyridine (PY), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), hexamethylphosphoramide (HMPA), methanol, ethanol andi-propyl alcohol. The electrophilic properties of binary aqueous-non aqueous solvent mixtures are determined both by selective solvation and specific solvent-solvent interactions. The variation of the acceptor number as a function of solvent composition is interpreted in terms of the previously determined nucleophilic and electrophilic properties of the pure components and their specific solvent structure.

Benzo(a)pyrene Metabolites Formed by Plant Cells

Abstract: Benzo (a) pyrene, added to the nutrient solutions of cell suspension cultures of Chenopodium rubrum, was metabolized to oxygenated derivatives. With increasing time of incubation decreasing amounts of the added ¹⁴C-radioactivity could be extracted with 70% methanol or be isolated as benzo (a) pyrene. The amount of metabolites formed increased with increasing time of incubation. After 48 hours most of the radioactivity was found in the extracted residue. These observations and some other indications give reason to believe that some of the metabolites are linked to proteins or nucleic acids.

Monomeric forms of the acid ionophore lasalocid A (X-537A) from polar solvents

Abstract: X-ray structural analyses have been carried out on the free acid of lasalocid A (X-537A) and on the sodium salt, both crystallized from methanol solution. In each case the structure is monomeric with one molecule of methanol complexing to the free acid and to the salt.

Process for manufacturing ethylene

Abstract: Ethylene is produced by catalytic conversion of a methanol feed in the presence of steam or water diluent. The catalyst employed is exemplified by HZSM-5, a crystalline aluminosilicate zeolite, and the conversion is conducted at relatively low temperature, i.e. from about 600° F to about 750° F. The hydrocarbon conversion product contains at least 18 wt.% ethylene.

Reduction of carbon monoxide to linear alcohols by aluminum hydrides and zirconium complex catalysts at room temperature

Abstract: DIBAH (i-Bu/sub 2/AlH in the presence of the cyclopentadienyl compound Cp/sub 2/ZrCl/sub 2/ as a catalyst) will reduce CO at room temperature and 1 to 4 atm to give, on hydrolysis, a mixture of the linear aliphatic alcohols methanol, ethanol, propanol, butanol, and possibly a trace of pentanol. A reaction mechanism is proposed. (JSR)

A study of catalysis by metal phosphates. IV. The alkylation of phenol with methanol over metal phosphate catalysts.

Abstract: The catalytic methylation in the vapor phase over various metal phosphates has been investigated using a conventional flow reactor at temperatures ranging from 350 to 500 °C under atmospheric pressure The Ca3(PO4)2 catalyst was excellent in both its activity and its selectivity for ortho-methylation, giving predominantly o-cresol and 2,6-xylenol, whereas the BPO4 or CaHPO4 catalyst simultaneously promoted the formation of anisole The activity of Ca3(PO4)2 was significantly higher than that of the CaO or MgO catalyst The influences of the reaction temperature, the contact time, and the calcination temperature of the catalyst upon the conversion of phenol, and the yields of the products were investigated in detail over the Ca3(PO4)2 catalyst The activities and the selectivities of various catalysts were discussed in connection with their acid-base properties The mechanism of the participation of both the acidic and basic sites in the methylation was also discussed

Fluorine-18-labeled diethylaminosulfur trifluoride (DAST): an F-for-OH fluorinating agent.

Abstract: A new fluorinating agent was developed by incorporation of 18F into diethylaminosulfur trifluoride (DAST), a reagent capable of replacing hydroxyl and carbonyl oxygen with fluorine. The DAST was synthesized using sulfur tetrafluoride and trimethylsilyldiethylamine in a freon-11 solvent at -78 degrees C and purified by reduced-pressure distillation. Labeling was then accomplished by exchange with anhydrous 18F-hydrofluoric acid, which caused more than 80% of the available activity to be incorporated into the DAST. Fluorine-18-labeled methyl fluoride, ethyl fluoride, and 2-fluoroethanol were prepared from methanol, ethanol, and ethylene glycol, with yields of 20%, 25%, and 12%, respectively.

Über Aminosäuren und Peptide, XX. über Dehydroaminosäuren, VII. Synthese von Dehydroaminosäureestern

Abstract: Durch N-Chlorierung und folgende Dehydrochlorierung in Gegenwart von Methanol erhalt man aus Boc-Aminosaureestern 1 die α-Methoxyderivate 2. Deren Behandlung mit HCl in Ather ergibt die Hydrochloride der entsprechenden α,β-Dehydroaminosaureester, aus denen mit NH3 die freien Enaminoester 3 erhaltlich sind. Als Nebenprodukte werden Imidazolinone 7 isoliert. On Amino Acids and Peptides, XX. On Dehydro Amino Acids, VII. Synthesis of Dehydro Amino Acids By N-chlorination and dehydrochlorination in the presence of methanol the α-methoxy derivatives 2 can be prepared from the Boc-amino acid esters 1. Reaction with HCl in ether yields the hydrochlorides of the corresponding α,β-dehydroamino acid esters. After treatment with NH3 the free enaminoesters 3 are obtained. As byproducts the imidazolinones 7 are isolated.