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Query: CAS:142-82-5 (heptane)
 3,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms that control the dissolution rates of chemical compounds in liquids have long been of interest to pharmaceutical scientists. Generally, control of the dissolution rate can be classified as being by interfacial reaction rate or by the rate of mass transport. Little work has been done in the area of sparingly soluble compounds dissolving in nonpolar organic solvents. In this study the dissolution of three isomers of methylacetanilide was investigated in three nonpolar organic solvents (hexane, heptane, and cyclohexane). The dissolution apparatus used a flat plate into which the nondisintegrating tablet could be placed so that dissolution occurred only from one face of the tablet. Agitation was provided by a four-bladed stirrer whose outer edge was 2 cm from the tablet surface. Dissolution data were collected only for concentrations less than 5% of the saturation solubility of the given compound in the given solvent. All dissolution profiles were linear. Dissolution rates were obtained from the slopes of these plots. Plots of In (dissolution rate) versus In (stirring speed) were also linear and yielded slopes that were close to the value of 0.50 predicted by the convective diffusion model employed.
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PMID:Determination of the dissolution rate controlling process for isomeric amides in alkane solvents. 382 Jan 6

Saline/air, blood/air, olive oil/air, and tissue/air (lung, kidney, liver, brain, muscle, heart, and fat) partition coefficients were determined for nine aliphatic hydrocarbons: n-pentane, 2,2-dimethylbutane, 3-methylpentane, 2-methylpentane, methylcyclopentane, n-hexane, cyclohexane, 3-methylhexane, and n-heptane. Blood/air partition coefficients were found to range between 0.38 (n-pentane) and 1.9 (n-heptane) and the value of the tissue/air partition coefficients rose from n-pentane to n-heptane. The tissue/air partition coefficients were significantly correlated with the blood/air partition coefficients (r = 0.92-0.98). According to the slope of the regression lines, the mean solubility of the nine aliphatic hydrocarbons in the different tissues was higher than in blood by the factors: lung 1.4 (range 1.2-2.1) heart 3.9 (range 0.5-4.5), liver 5.6 (range 5.5-13.5), kidney 5.2 (range 1.6-5.8), brain 6.5 (range 5.8-10.7), muscle 7.6 (range 1.8-8.8), and fat 205 (range 104-254). The blood/air and olive oil/air partition coefficients were significantly correlated with the boiling points and the molecular weights of the aliphatic hydrocarbons studied.
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PMID:Partition coefficients of some industrial aliphatic hydrocarbons (C5-C7) in blood and human tissues. 397 Aug 80

Four different isolates of Cladosporium resinae from Australian soils were tested for their ability to utilize liquid n-alkanes ranging from n-hexane to n-octadecane under standard conditions. The isolates were unable to make use of n-hexane, n-heptane, and n-octane for growth. In fact, these hydrocarbons, particularly n-hexane, exerted an inhibitory effect on spore germination and mycelial growth. All higher n-alkanes from n-nonane to n-octadecane were assimilated by the fungus, although only limited growth occurred on n-nonane and n-decane. The long chain n-alkanes (C(14) to C(18)) supported good growth of all isolates, but there was no obvious correlation between cell yields and chain lengths of these n-alkanes. Variation in growth responses to individual n-alkane among the different isolates was also observed. The cause of this variation is unknown.
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PMID:Utilization of n-alkanes by Cladosporium resinae. 473 47

The induction of paraffin oxidation in intact cells of Pseudomonas aeruginosa was investigated. Oxidation of (14)C-heptane by cell-free extracts of adapted cells showed that the activity of whole cells is a reliable reflection of the synthesis of the first enzyme in the degradation of n-alkanes. Induction was significantly affected by glucose and could be completely repressed by malate. The amino acids l-proline, l-alanine, l-arginine, and l-tyrosine exhibited a rather low repressor action. Malonate, a nonrepressive carbon source, allowed gratuitous enzyme synthesis. A number of compounds which did not sustain growth were found to be suitable substitutes for paraffins as an inducer. Among these were cyclopropane and diethoxymethane. The induction studied under conditions of gratuity with the latter compound as an inducer showed immediate linear kinetics only at saturating inducer concentrations. With n-hexane as the inducer, a lag time was always observed, even when high concentrations were used.
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PMID:Paraffin oxidation in Pseudomonas aeruginosa. I. Induction of paraffin oxidation. 497

Solubilities are reported for benzoic acid at 25.0 degrees in binary mixtures of carbon tetrachloride with cyclohexane, n-hexane, or n-heptane and of cyclohexane with n-hexane or n-heptane and in ternary mixtures of carbon tetrachloride-cyclohexane-n-hexane and carbon tetrachloride-cyclohexane-n-heptane. Solubilities also are reported for benzoic acid in some binary solvents at 30.0 degrees and for m-toluic acid in binary mixtures of cyclohexane and n-hexane at 25.0 degrees. The results are compared to the predictions of equations developed previously for solubility in systems of purely nonspecific interactions, with the benzoic acids considered as either monomeric or dimeric molecules in solution. The dimer model gave more accurate predictions, with a maximum deviation of 4.4% between observed and predicted solubilities in all systems studied. Solubility maxima were predicted and observed for benzoic and m-toluic acids in cyclohexane-n-hexane and for benzoic acid in cyclohexane-n-heptane. The application of these solubility relationships to liquid-liquid partition coefficients is discussed.
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PMID:Thermochemical investigations of nearly ideal binary solvents. VII: Monomer and dimer models for solubility of benzoic acid in simple binary and ternary solvents. 610 Nov 49

Rats were intermittently exposed (9 to 10 h/d, 5 to 6 d/week) to controlled concentrations of single analytical grad solvents in ambient air. After periods ranging from 7 to 30 weeks the animals were perfused with glutaraldehyde and samples of nerves were processed for light microscopy of sections and of teased fibers. Animals treated with n-hexane at 5000 ppm (14 weeks) or 2500 ppm (30 weeks) developed the typical giant axonal degeneration already described in rats treated continuously with 400 to 600 ppm of the same solvent for 7 weeks or more. No such alterations were found in rats subjected to the following intermittent respiratory treatments: n-hexane 500 ppm (30 weeks) or 1500 ppm (14 weeks), cyclohexane 1500 or 2500 (30 weeks), n-pentane 3000 ppm (30 weeks), n-heptane 1500 ppm (30 weeks), 2-methylpentane 1500 ppm (14 weeks), and 3-methylpentane 1500 ppm (14 weeks). The following metabolites were found in the urine of rats according to treatment (in parenthesis): 2-methyl-2-pentanol (2-methylpentane); 3-methyl-2-pentanol and 3-methyl-3-pentanol (3-methylpentane), 2-hexanol, 3-hexanol, gamma-valerolactone, 2,5-dimethylfuran, and 2,5-hexanedione (n-hexane). 2-Hexanol was found to be the main urinary metabolite of n-hexane, while 2,5-hexanedione was present only in a lesser proportion. This feature of rat metabolism suggests that in this species 2,5-hexanedione reaches an effective level at its site of action during intermittent respiratory treatment with n-hexane with difficulty and explains the high concentrations necessary to cause polyneuropathy in rats subjected to this treatment.
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PMID:Experimental neurotoxicity and urinary metabolites of the C5-C7 aliphatic hydrocarbons used as glue solvents in shoe manufacture. 627 48

After voluntary inhalation of a domestic solvent containing N-Hexane and N-Heptane for three months, a 23-year-old woman developed motor deficit of the lower limbs, sensory symptoms and areflexia. Clinical disorders continued to progress after discontinuation of the intoxication, with a parallel aggravation of the E.M.G. disturbances. A nerve biopsy with ultrastructural study showed axon dilatation with accumulation of neurofilaments. The clinical, electrophysiological and pathological features of neuropathies induced by hexacarbon solvents are reviewed and their pathogenesis is discussed.
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PMID:[Peripheral neuropathy due to N-hexane in a drug addict (author's transl)]. 628 54

This paper summarizes the knowledge and recent research of some organic neurotoxic substances at the workplace concerning peripheral nervous system. The review covers the substances: acrylamide, n-hexane, methyl-n-butylketone, n-pentane, n-heptane, carbondisulfide, styrene, toluene, trichloroethylene, tri-ortho-cresylphosphate and other organophosphorus compounds, polyhalogenated and complex organic compounds and solvent-mixtures. First the chemical and physical properties, the toxicokinetic and biotransformation as well as possibilities of exposure at the workplace are given. Following the characteristics after acute and chronic intoxications. The effects to the peripheral nervous systems due to short- and longtime exposure of the substance are described. Field studies in exposed workers and neurophysiological investigations with evaluation of dose-effect-relationships are reviewed especially. Each section is discussed and evaluated in respect to occupational medicine.
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PMID:[Neurotoxic workshop materials: II. Organic substances--a review of the years 1970 to 1982]. 636 84

It has been shown in rat experiments that isonarcotic concentrations of inhalation anesthetics (pentane, hexane, heptane) varied in the brain depending on the regimen of monoanesthesia. It has been demonstrated that the high content of anesthetics in the priming mixture results in a decline of the isoeffective brain concentration. Preliminary anesthesia leads to an increase in this indicator. The data obtained are accounted for by distributive processes in the biophase-adjacent structure system.
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PMID:[General inhalant anesthetics: the dependence of the narcotic effect on the concentration in the brain]. 647 9

The spherically agglomerated crystals of aminophylline (theophylline-ethylenediamine complex) can be compounded directly into pharmaceutical formulations without further processing, e.g., granulation. Such crystals were prepared by mixing theophylline and ethylenediamine in a partially miscible solvent system, i.e., organic solvent-ethanol-water. The organic solvents used were chloroform, 1-hexanol, isopropyl acetate, isobutyl acetate, isoamyl acetate, benzene, toluene, n-hexane, or n-heptane. Spherical crystallization depended upon the solubility of theophylline in the solvent mixture. The resultant agglomerated crystals were identical with the theophylline-ethylenediamine complex by IR, X-ray, and differential scanning calorimetry analyses, and was the alpha-, beta-, or gamma-form when the water of crystallization was less than or equal to 0.5, 1.0, and 2.5 mol, respectively. When the amount of ethylenediamine used was less than 1.1 mL (0.0165 mol), the resultant agglomerated crystals were converted to anhydrous theophylline by washing with ethanol. When water was added to the system (greater than or equal to 0.3 mL, i.e., 0.0167 mol), water was occluded in the resultant agglomerates as water of crystallization. Ethylenediamine content in the agglomerated crystals could be controlled by changing the amount of ethylenediamine added in the crystallization solvent.
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PMID:Preparation of spherically agglomerated crystals of aminophylline. 650 90


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