Showing papers on "Aromatic hydrocarbon published in 1991"

Aromatic hydrocarbon responsiveness-receptor agonists generated from indole-3-carbinol in vitro and in vivo: comparisons with 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Abstract: Indole-3-carbinol (I3C) is a secondary plant metabolite produced in vegetables of the Brassica genus, including cabbage, cauliflower, and brussels sprouts. I3C is both an anti-initiator and a promoter of carcinogenesis. Consumption of I3C by humans and rodents can lead to marked increases in activities of cytochrome P-450-dependent monooxygenases and in a variety of phase II drug-metabolizing enzymes. We have reported previously that the enzyme-inducing activity of I3C is mediated through a mechanism requiring exposure of the compound to the low-pH environment of the stomach. We report here the aromatic hydrocarbon responsiveness-receptor Kd values (22 nM-90 nM), determined with C57BL/6J mouse liver cytosol and the in vitro- and in vivo-molar yields (0.1-6%) of the major acid condensation products of I3C. We also show that indolo[3,2-b]carbazole (ICZ) is produced from I3C in yields on the order of 0.01% in vitro and, after oral intubation, in vivo. ICZ has a Kd of 190 pM for aromatic hydrocarbon responsiveness-receptor binding and an EC50 of 269 nM for induction of cytochrome P4501A1, as measured by ethoxyresorufin O-deethylase activity in murine hepatoma Hepa 1c1c7 cells. The binding affinity of ICZ is only a factor of 3.7 x 10(-2) lower than that of the highly toxic environmental contaminant and cancer promoter 2,3,7,8-tetrachlorodibenzo-p-dioxin. ICZ and related condensation products appear responsible for the enzyme-inducing effects of dietary I3C.

Partitioning of aromatic constituents into water from gasoline and other complex solvent mixtures

Abstract: Variations in gasoline composition (source variations) as well as complexity (nonideal behavior, cosolvent effects) contributing to variability in gasoline-water partitioning of aromatic hydrocarbon constituents were examined. Aromatic hydrocarbon concentrations in water extracts of 31 gasoline samples varied over 1 order of magnitude, reflecting the diversity in gasoline composition. However, the gasoline-water partition coefficients (K{sub fw}) varied by less than 30% among these samples. Partitioning between water and known mixtures of aromatic and aliphatic solvents was measured and used to estimate the upper and lower bounds of K{sub fw} values for more complex solvent mixtures such as gasoline and diesel fuel. Oxygenated additives, such as methanol and methyl tert-butyl ether (MTBE), were shown to have minimal cosolvent effects on hydrocarbon partitioning. The observed inverse, log-log linear dependence of K{sub fw} values on aqueous solubility could be well predicted by assuming gasoline to be an ideal solvent mixture (i.e., Raoult's law is valid).

Aromatic hydrocarbon degradation: a molecular approach.

Abstract: Aromatic hydrocarbons have a ubiquitous distribution in nature. The majority of these compounds are formed through the pyrolysis of organic matter. Pyrolysis at high temperatures leads to the formation of unsubstituted polycyclic aromatic hydrocarbons (1). Pyrolysis at low temperatures, such as those at which crude petroleum is formed, leads to the formation of alkyl-substituted aromatic hydrocarbons (1). Many of these compounds are suspected carcinogens. Increased use of petrochemicals by modern society has increased the amount of aromatic hydrocarbons found in air and soil samples (2,3). It is not surprising then that due to the ubiquitous nature and increasing concentrations of aromatic hydrocarbons microorganisms can be found that have the ability to degrade these compounds. The varied mechanisms by which microorganisms utilize aromatic hydrocarbons as carbon and energy sources have been the focus of several reviews (4–10).

Polyacrylic acid compositions for textile processing

Abstract: Novel polyacrylic acid resins are prepared by polymerizing H2C=CHCO2H, H2C=CRCO2X, or HRC=CHCO2X, wherein R is an aliphatic or aromatic hydrocarbon, halogenated hydrocarbon, or sulfonated hydrocarbon of from C1 to C20, phenol, naphthol, sulfonated phenol, sulfonated naphthol, or a halogen, and X is hydrogen, alkyl, or a hydroxylated, ethoxylated, sulfonated, or halogenated aliphatic or aromatic hydrocarbon of from C1 to C20, sodium, potassium, ammonium, or quaternary amine, in the presence of aromatic sulfonic acid or its salt to form a polymer in which the sulfonated aromatic compound is covalently bound to the polymer. In an alternative embodiment, a textile processing or cleansing compound is included in the polymerization reaction along with the acrylic acid and aromatic sulfonic acid or its salt. The resulting polymers have superior properties for use in textile processing and cleaning, and can be used as detergents, acid dye levelers, surfactans, emulsifiers, yarn lubricants, copolymerizing agents, polymer after treat agents, defoamers, chelating agents, flocculants, anti-static agents, flame retardants, metal cleaners, metal coatings, and as multipurpose acids.

Alkylation using zeolite SSZ-25

Abstract: A process for the alkylation of an aromatic hydrocarbon which comprises contacting the aromatic hydrocarbon with a C 2 to C 4 olefin alkylating agent under at least partial liquid phase conditions, and in the presence of a catalyst comprising zeolite SSZ-25. The invention also provides a process for producing a reduced benzene content gasoline blend stock. A benzene-containing light hydrocarbon stream having less than 50 weight present benzene is contacted with a C 2 -C 4 olefin stream in an alkylation zone containing an SSZ-25 catalyst under alkylation conditions to produce an alkylated light hydrocarbon stream with reduced benzene content. The alkylated light hydrocarbon stream is then usable as gasoline blend stock.

Process for the preparation of aromatic beta-diketones

Abstract: A process for the preparation of aromatic beta-diketones having the structural formula (see formula I) by the reaction of an acetophenone and a molar excess of an alphatic ester or an ester of benzoic acid in the presence of sodium alkoxide condensation agent in an aromatic hydrocarbon solvent. Also disclosed is a method of recycling the solvent and excess ester reactant after separation of the aromatic beta-diketone product.

Aromatic hydrocarbon derivatives of fullerences

Abstract: The fullerences C60 and C70 form adducts with toluene, p-xylene and other aromatic compounds when refluxed in these solvents in the presences of FeCl3. Benzene derivatives are produced only when bromine is also present. Mass spectra of the reaction mixtures indicate the presence of derivatives including 1:1 adducts, as well as products of multiple additions of the aromatic molecules and their dehydrogenation products. Tandem mass spectrometry provides evidence for CC bonds formation between the adducts and fullerences.

Rules of molecular geometry for predicting carcinogenic activity of unsubstituted polynuclear aromatic hydrocarbons.

Abstract: The rules of molecular geometry for predicting carcinogenic activity of polynuclear aromatic hydrocarbons (PAH) have been applied to a series of 50 unsubstituted PAH, and predicted carcinogenic activity is in good agreement with the results of testing for complete carcinogenic activity in mice and/or rats. The rules were developed from a knowledge of the center or centers of highest chemical or biochemical reactivity and are consistent with a unified hypothesis which states that the first step in the metabolic activation of unsubstituted PAH is the biochemical introduction of a methyl group. This bioalkylation reaction 1) takes place between certain PAH and S-adenosyl-L-methionine and is catalyzed by cytosolic methyltransferase, 2) offers a means of probing for centers of reactivity in PAH, 3) provides a biochemical link between unsubstituted preprocarcinogens of aromatic type ArX and alkyl-substituted procarcinogens of aromatic type ArCH2X (where X = H), and 4) makes it possible to include compounds of both aromatic types, in a consistent theory of aromatic hydrocarbon activation which incorporates alkyl substitution. The present study reveals that there are structural determinants of carcinogenicity.

New imide derivative

Abstract: PURPOSE:To provide a new imide derivative useful as a substance having antipsychotic and/or anxiety eliminating actions without any side effects. CONSTITUTION:A compound expressed by formula I{Z is formula II [B is carbonyl or sulfonyl; R to R are H or alkyl, provided that R and R or R and R together may form hydrocarbon rung or R and R together may form aromatic hydrocarbon rung; (n) is 0 or 1]; Z is formula III [A is alkylene or hydrocarbon ring which may be crosslinked with O; (p) and (q) are 0-2]; G is N, CH or COH; Ar is aromatic heterocyclic group, aromatic hydrocarbon group, benzoyl, phenoxy, phenylthio or G is C and Ar is biphenylmethylidene} or its salt, e.g. a compound expressed by formula IV. The aforementioned compound expressed by formula IV is obtained by reacting N-[(2-chloromethyl) cyclopropylmethyl]cyclohexane-1,2-dicarboximide with 3-(1-piperazinyl)-1,2- benzisothiazole.

A process for preparing alkyl-substituted aromatic hydrocarbons.

Abstract: An alkyl-substituted hydrocarbon is prepared effectively under mild conditions by alkylating an alkyl aromatic hydrocarbon having at least one hydrogen atom at an alpha-position in a side chain with an olefin in the presence of a solid base which is obtainable by treating a water-containing oxide of an alkaline earth metal with at least one material selected from the group consisting of alkali metals and alkali metal hydrides in an amount of 0.5 to 3.5 equivalents per one mole of water in said oxide in an inert gas atmosphere.

Production of aromatic hydrocarbon

Abstract: PURPOSE:To solve problems of lowering in aromatic yield by the lowering in the activity of a catalyst by improving the flow process of a reactional product when 2-7C aliphatic hydrocarbons are converted to aromatic hydrocarbons. CONSTITUTION:A mixture of an aliphatic hydrocarbon as a raw material with a light-weight hydrocarbon gas containing methane and/or ethane is passed through a conversion reaction zone 1 in which a catalyst consisting essentially of an aluminogallosilicate is retained, and then the reactional products are divided into a cracked gas and a separation liquid by the first separation zone 2, 3 and 4. The cracked gas is separated into a hydrogen-containing gas and a recycle gas having high methane and/or ethane contents in a hydrogen separating apparatus 6. On the one hand, a separated liquid from the first separation zone is separated to aromatic hydrocarbons and a low boiling hydrocarbon gas in the second separation zone 5. The low boiling hydrocarbon gas and the recycle gas as the light-weight hydrocarbon gas are mixed with the aliphatic hydrocarbon gas of the raw material. Then, in a conversion reaction zone 1, the reaction temperature is continuously or step by step raised to retain the aromatic yield in a definite range.

Identification of the major metabolites and DNA adducts formed from 2-nitropyrene in vitro.

Abstract: In contrast to 1-nitropyrene (1-NP), which is the most abundant nitropolycyclic aromatic hydrocarbon in numerous environmental sources, 2-nitropyrene (2-NP) has been detected only in the ambient air and not in direct emissions. Thus, 2-NP can be used as an indicator for monitoring human exposure to nitropolynuclear aromatic hydrocarbons in ambient air. Therefore, it is essential to determine the possible metabolic pathways of 2-NP. The metabolism of 2-NP by rat liver 9000 g supernatant was investigated. Under aerobic conditions, ring oxidation to 6-hydroxy-2-nitropyrene and nitroreduction to 2-aminopyrene (2-AP) were observed. When incubations were carried out in an atmosphere of nitrogen, 2-AP was the only metabolite detected. These results are consistent with those observed with 1-NP. In vitro metabolic activation of 2-NP to DNA adducts catalyzed by xanthine oxidase was also examined. Two adducts were characterized as N-(deoxyguanosin-8-yl)-2-aminopyrene and N-(deoxyadenosin-8-yl)-2-aminopyrene. The presence of deoxyadenosine adduct, which is derived from the nitroreduction pathway, may contribute to the powerful direct-acting mutagenicity of 2-NP.

Liquid-liquid equilibria for ternary systems formed by acetonitrile, water, and aromatic hydrocarbons

Abstract: Liquid-liquid equilibria were measured at 25 and 45 o C for the ternary systems formed by acetonitrile + water + an aromatic hydrocarbon (benzene, toluene, m-xylene, p-xylene, ethylbenzene). Type I isotherms were observed for the five systems both at 25 and 45 o C. The binodal curves and tie lines may be predicted by using the NRTL model on the basis of parameters found from binary data

Process for producing alkyl-substituted aromatic hydrocarbon using heteropolyacid salts

Abstract: A process for producing an alkyl-substituted aromatic hydrocarbon, which comprises alkylating an aromatic hydrocarbon with an alkylating agent in the presence of a heteropoly-acid or a salt thereof such as phosphorus tungstate and silicon tungstate as a catalyst. The process is particularly useful for preparing alkyl-substituted naphthalene or naphthalene derivatives.

The metabolism of benzene to muconic acid, a potential biological marker of benzene exposure.

Abstract: Benzene, the simplest aromatic hydrocarbon, is a ubiquitous environmental pollutant. It is a volatile compound, extensively used in industry as an important synthetic intermediate. It is also an additive in gasoline. In addition to occupational exposure, a major human exposure results from cigarette smoke (Wallace, 1989). The toxicity of benzene as a leukemogen in humans (Goldstein, 1977) and a hematotoxic and carcinogenic agent in experimental animals (Snyder and Kocsis, 1977; Maltoni et al., 1989) has been well established. It is generally accepted that benzene toxicity is mediated by metabolites (Snyder et al., 1981). The nature of the metabolite(s) responsible for benzene toxicity is at present not known.

Improved catalytic process for selective alkylation of aromatic hydrocarbons

Abstract: A catalytic process for the selective alkylation of mono- and polycyclic aromatic hydrocarbons is described. The aromatic hydrocarbon is reacted with an alkylating agent in the presence of an acid form of a dealuminated small pore mordenite catalyst having an atomic ratio Si/Al of at least 10:1 to thereby yield the desired alkyl substituted derivative with improved selectivity and improved yield.

Charge Transfer and Hydrogen Transfer in Polyaromatic Hydrocarbons

Abstract: This paper presents characteristic studies on charge transfer and hydrogen transfer in aromatic hydrocarbon molecules. Several significant articles have been referred to and discussed, covering the following items: (1) electron donor ability, (2) hydrogen donor ability of aromatic hydrocarbons, and (3) interaction of aromatic hydrocarbons with various catalysts.The studies concentrate particularly on hydrogen bondings and aromatic π-π interactions with respect to the charge transfer between polyaromatic hydrocarbons and electron acceptors as guests. To obtain fundamental information about hydrogen transfer, the relationship between hydrogen donor ability and chemical structure of aromatics representing donor solvents is studied using experimental and computational calculation methods. Furthermore, the influence of the addition of metal oxide catalysts on transferable hydrogen in petroleum residue is studied by 1H-NMR technique. Also, the interaction of anthracene/metal chloride and petroleum metal chloride systems was investigated by means of high temperature ESR technique. Finally, the H-D exchange reaction of hydrogen atoms attached to condensed aromatics with deuterium atom in D2O over the catalyst was studied by means of D-NMR.

Photodynamics of the S1 State of Some Hydroxy- and Amino-substituted Naphthoquinones and Anthraquinones.

Abstract: Photodynamics of the S1 state of the 1,4- and 1,8-disubstituted hydroxyquinones and aminoquinones have been studied in different organic solvents by absorption and fluorescence spectroscopy. The internal conversion process is the major deactivation path for the S1 state. The solvent and temperature dependence and deuterium isotope effect on the fluorescence dynamics suggest that hydrogen stretching vibrations in different intra- and inter-molecular hydrogen bonds are responsible for very fast non-radiative decay processes. Among the intra-molecular hydrogen-bonded molecules studied only the S1 state of 1,8-dihydroxy-9,10-anthraquinone showed the evidence of excited-state intramolecular proton-transfer process. Preliminary observations on the interaction of the S1 state of these quinones with benzene and other aromatic hydrocarbon solvents via the formation of an exciplex have also been reported.

Hydroalkylation of aromatic hydrocarbons

Abstract: A process for converting aromatic hydrocarbons (in particular benzene) to cycloalkyl-substituted aromatic hydrocarbons (in particular cyclohexylbenzene) in the presence of free hydrogen and a palladium-promoted zeolite catalyst is carried out in the presence of carbon monoxide as process modifier (so as to enhance the selectivity to the cycloalkyl-substituted aromatic hydrocarbon).

Process for the decolouration of resinous polymers of the vinyl aromatic/conjugated diene type

Abstract: Vinyl aromatic-conjugated diene copolymers having polymer chains which end with an alkali metal and which are obtained by the polymerization in solution of at least one vinyl aromatic hydrocarbon and of a conjugated diene in the presence of a catalyst based on an alkali metal are decolorized by treating the copolymer with a monocarboxylic acid of general formula (Y)2-n - X - (R-COOH)n in which X is S, S-CH2-S, or (S-S), and Y and R are alkyl radicals having 1 to 16 carbon atoms and n is 1 or 2.

Process for producing alkyl-substituted aromatic hydrocarbon

Abstract: A process for producing an alkyl-substituted aromatic hydrocarbon, which comprises alkylating an aromatic hydrocarbon with an alkylating agent in the presence of a heteropoly-acid or a salt thereof such as phosphorus tungstate and silicon tungustate as a catalyst.

Acyl-(2'-hydroxydiphenyl-2-yl)-phosphinic acid salts, their production and use

Abstract: The invention relates to acyl-(2'-hydroxydiphenyl-2-yl)-phosphinic acid salts of formula (I) in which each of the radicals R?1, R2 and R3? may be included singly or multiply and in which R?1 and R2? are mutually independently hydrogen, an alkyl or alkoxy radical with 1 to 6 carbon atoms or halogen with an atomic number of 9 to 35; R3 means the same as R1/R2; Ar is an aromatic hydrocarbon radical with 6 to 10 carbon atoms; and Me is a cation of at least one alkaline metal or N(R4)4+ in which the radicals R4 are the same or different and stand for an alkyl radical with 1 to 6 carbon atoms. The invention also relates to a process for producing these compounds (I) and their use as photoinitiators in photopolymerisable materials, preferably on an aqueous basis.

Polymers capable of oxidative crosslinking

Abstract: Mo3655 LeA 27,954 POLYMERS CAPABLE OF OXIDATIVE CROSSLINKING ABSTRACT OF THE DISCLOSURE The present invention relates to polymers capable of oxidative crosslinking, characterized in that they contain 10 to 80% by weight of structural units corresponding to formula (I) and/or (Ia) (I) (Ia) wherein R1 is an aliphatic saturated hydrocarbon radical containing 2 to 6 carbon atoms, provided that at least 2 carbon atoms are arranged between the nitrogen atom and the oxygen atom, and R2 at least 30% of the substituents R2 are monoolefinically or polyolefinically unsaturated hydrocarbon radicals and the remainder, i.e. up to 70% of the substituents R2, are saturated aliphatic and/or aromatic hydrocarbon radicals which may optionally contain oxygen and/or nitrogen as hetero atoms in the form of ether, ester, keto, urethane, urea and/or amide groups, provided that substituent R2 contains at least 2.0% by weight, based on the weight of the polymer, of aliphatically unsaturated double bonds, expressed as C=C (molecular weight = 24). The present invention also relates to a process for the production of these polymers and to the use of these polymers as binders or binder component for coating or sealing compositions. Mo3655

Process for producing bistrimellitic imide

Abstract: A process for producing a bistrimellitic imide of the formula (2) ##STR1## wherein X is an aliphatic group having at least 2 carbon atoms, an alicyclic group or an aromatic group, which comprises reacting a trimellitic anhydride with a diamine of the formula (1) H.sub.2 N--X--NH.sub.2 (1) wherein X is as defined above, in the presence of a solvent mixture containing an aprotic polar solvent and an aromatic hydrocarbon solvent which can be distilled azeotropically with water, the amount of the aromatic hydrocarbon solvent being 10 to 90% by weight based on the total weight of these two solvents.

Process for producing styrenes resin transparent and anti-shock

Abstract: Process for the manufacture of block copolymers, consisting in polymerising anionically in a solvent medium in a first stage a hydrocarbon vinylaromatic monomer and, in a second stage, a conjugated diene, characterised in that, in the first stage, the hydrocarbon vinylaromatic monomer is polymerised in solution in an aromatic hydrocarbon solvent until a homogeneous mixture is obtained with a viscosity higher than 300 Pa s at 20 DEG C at a polymer concentration of between 60 and 90 % by weight in the aromatic hydrocarbon solvent and in that, in a second stage, after introduction of conjugate diene, copolymerization is performed until a homogeneous mixture is obtained with a viscosity higher than 300 Pa s at 90 DEG C at a copolymer concentration of between 70 and 90 % by weight in the hydrocarbon aromatic solvent, without the viscosity exceeding 3,000 Pa s in the two stages.

Production of syndiotactic polypropylene

Abstract: PURPOSE:To obtain a syndiotactic polypropylene in high yields per unit weight of catalyst by polymerizing propylene in the presence of a transition metal catalyst having asymmetrical ligands and an aluminoxane catalyst in a small amount of an aromatic hydrocarbon compound and polymerizing liquid propylene by using the formed slurry. CONSTITUTION:Propylene (0.1-10000g per g of the transition metal catalyst) is polymerized in the presence of a catalyst comprising a transition metal catalyst having asymmetrical ligands (e.g. isopropyl(cyclopentadienyl-1-fluorenyl) hafnium dichloride) and an aluminoxane in a small amount of an aromatic hydrocarbon solvent such as toluene. The aromatic hydrocarbon is used in an amount of 10ml-1000l per g of the transition metal catalyst. Liquid propylene (at least 10ml per ml of the transition metal catalyst) is bulk-polymerized to obtain a syndiotactic polypropylene.

Process for purifying dimethyl 2,6-naphthalene dicarboxylate

Abstract: A process for purifying crude 2,6-naphthalene dimethyl dicarboxylate (hereinunder referred to as 2,6-NDM) which comprises dissolving the crude 2,6-NDM into a C6 -C9 aromatic hydrocarbon, then contacting the solution of 2,6-NDM and the hydrocarbon with an hydrotalcite-like laminar crystalline compound and activated carbon, then carrying out thermal filtration of the solution, and then cooling the solution to separate 2,6-NDM crystal from the solution is disclosed.

Process for producing polyhydroperoxy aromatic compound

Abstract: A process for producing a polyhydroperoxy aromatic compound by oxidation of an aromatic hydrocarbon, e.g., 4,4'-diisopropylbiphenyl and 4,4'-diisopropylnaphthalene, with molecular oxygen is disclosed, in which the oxidation is carried out in the presence of a metal ion selected from cobalt, nickel, zinc and lead ions. Even in using a reaction apparatus made of an iron-containing metal generally employed in industry, a high conversion of secondary alkyl groups can be reached, and the desired polyhydroperoxy aromatic compound can be obtained in a high yield.