Electrophilic additions to strained alkenes. II. The reaction of benzeneselenenyl chloride with tricyclo[4.2.2.02,5]deca-3,7-diene derivatives

1980 ◽  
Vol 58 (22) ◽  
pp. 2329-2339 ◽  
Author(s):  
Dennis G. Garratt ◽  
M. Dominic Ryan ◽  
Ann Kabo
Keyword(s):  
Acetic Acid ◽  
Methylene Chloride ◽  
Solvent System ◽  
Major Product ◽  
Kinetic Control ◽  
Solvent Systems ◽  
Electrophilic Additions ◽  
Strained Alkenes ◽  
Derivatives Of

The reactions of benzeneselenenyl chloride with three derivatives of tricyclo[4.2.2.02,5]deca-3,7-diene have been investigated in four solvent systems: methylene chloride, acetic acid, acetic acid/LiClO4, and methanol. Under conditions of kinetic control only products of exo–anti attack upon the cyclobutene moiety are isolable when the solvent system is methylene chloride or acetic acid. This observation also holds in acetic acid/LiClO4 except in the case of dimethyl tricyclo[4.2.2.02,5]deca-3,7,9-triene-7,8-dicarboxylate where the major product is that of cross-bonding with solvent incorporation. In methanol products of solvent incorporation, transannular cross-bonding and lactonization (where possible) are observed. A general mechanistic scheme is proposed to account for these observations in accord with earlier results for the analogous arenesulphenylations.

Susceptibility of Strawberries, Blackberries, and Cherries to Aspergillus Mold Growth and Aflatoxin Production

1982 ◽  
Vol 65 (3) ◽  
pp. 659-664 ◽  
Author(s):  
Gerald C Llewellyn ◽  
Thomas Eadie ◽  
William V Dashek
Keyword(s):  
Acetic Acid ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Mycelial Growth ◽  
Methylene Chloride ◽  
Aflatoxin Production ◽  
Solvent System ◽  
Mold Growth ◽  
Tlc Plates ◽  
Layer Chromatography

Abstract The susceptibility of blackberries, cherries, and strawberries to Aspergillus growth and aflatoxin production has been examined. Three aflatoxigenic isolates of Aspergillus, A. flavus ATCC 15548 and NRRL 3251 as well as A. parasiticus NRRL 2999, were cultured on homogenates of the fruits for 14 days at 28 ± 2°C. Percent mycelial growth and spore infestation were determined each day with a calibrated grid. At day 14 each culture was frozen at –5°C until aflatoxins were extracted with methylene chloride and water. Aflatoxins were separated by thin layer chromatography (TLC) with benzene-methanol-acetic acid (90 + 5 + 5). This extraction and solvent system provided satisfactory separations of the aflatoxins and was free of background interference on the TLC plates. Although all fruits served as substrates for both Aspergillus growth and aflatoxin production, cherries appeared to be a more favorable substrate than did blackberries, and the latter was more favorable than strawberries. Whereas A. flavus produced both B1 and G1 on all substrates, it yielded B2 and G2 only on cherries. Although A. parasiticus NRRL 2999 synthesized B1, B2, G1, and G2 on both blackberries and cherries, no aflatoxins were detected on strawberries. In contrast, A. flavus NRRL 3251 failed to produce detectable levels of aflatoxin on any substrate. All substrates supported both mycelial growth and subsequent sporulation with cherries > blackberries > strawberries.

Simplified Qualitative Analysis of Glycerides Derived from Coconut Oil Using Thin Layer Chromatography

2012 ◽  
Vol 506 ◽  
pp. 182-185 ◽  
Author(s):  
Sirikarn Pengon ◽  
Chutima Limmatvapirat ◽  
Sontaya Limmatvapirat
Keyword(s):  
Acetic Acid ◽  
Qualitative Analysis ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Cocos Nucifera ◽  
Coconut Oil ◽  
Solvent System ◽  
Tlc Plates ◽  
Solvent Systems ◽  
Layer Chromatography

Coconut (Cocos nucifera L.) oil is composed predominately of medium-chain triglycerides which have been reported to be beneficial to human health. It also contains free fatty acids (FFAs) which can combine with glycerol to form monoglycerides, diglycerides, and triglycerides. The analysis of FFAs and their glycerides has been proposed to assess the quality of coconut oil used as raw materials in various industrial fields. The aim of this study was to develop the qualitative method for investigation of FFA and their glycerides in coconut oil using thin layer chromatography (TLC). Coconut oil and standards of FFA and their glycerides were chromatographed separately on Silica gel 60 F254 TLC plates using hexane: ether: acetic acid (60:40:1) and hexane: ethyl acetate: acetic acid (60:40:0.5) as solvent systems A and B, respectively. The spots on developing TLC plates were detected and compared using 254-nm UV light and iodine vapor. The results showed that the resolution of solvent system A was better than that of solvent system B. However, both solvent systems were used to confirm the results. The retention factor (Rf) values of the components were in good agreement with their polarity. This method should provide a guideline for qualitative analysis of coconut oil.

Some Effects of Replacement of Metaphosphoric Acid/Acetic Acid Solvent System with Trichloroacetic Acid in Microfluorometric Determination of Vitamin C

1984 ◽  
Vol 67 (5) ◽  
pp. 1020-1022
Author(s):  
Frans R Visser
Keyword(s):  
Acetic Acid ◽  
Vitamin C ◽  
Trichloroacetic Acid ◽  
Fluorescence Enhancement ◽  
Fold Increase ◽  
Solvent System ◽  
Metaphosphoric Acid ◽  
Comparative Advantages ◽  
Solvent Systems

Abstract Trichloroacetic acid (TCA) is suggested as a substitute for the metaphosphoric acid/acetic acid (HPO3-HOAc) solvent system in the AOAC microfluorometric determination of vitamin C. Comparative advantages of TCA are easier handling, greater stability, and the approximate 10-fold increase in sensitivity. For both solvent systems, the influence of acid concentration on fluorescence is described. TCA provides maximum fluorescence enhancement at pH 5.5-6.0.

CHROMATOGRAPHIC IDENTIFICATION OF ESTRIOL AND 16,17-EPIESTRIOL AS CONSTITUENTS OF THE URINE OF THE LAYING HEN

1967 ◽  
Vol 45 (4) ◽  
pp. 531-539 ◽  
Author(s):  
R. S. Mathur ◽  
R. H. Common
Keyword(s):  
Reference Material ◽  
Thin Layer ◽  
Solvent System ◽  
Alumina Column ◽  
Hydrophilic Fraction ◽  
Alumina Column Chromatography ◽  
Phenolic Extract ◽  
Solvent Systems ◽  
Layer Chromatography ◽  
Derivatives Of

Presumptive estriol and 16,17-epiestriol fractions were separated from laying hens' urine by subjecting the hydrophilic fraction of the urinary phenolic extract to successive thin-layer chromatography (t.l.c), alumina-column chromatography, further t.l.c, and finally, microsublimation. The presence of estriol in the presumptive estriol fraction was confirmed by comparison of the thin-layer chromatographic behaviors of the phenol and four derivatives thereof with the behaviors of reference estriol and four corresponding derivatives of this reference material each in three different solvent systems. The presence of 16,17-epiestriol in the presumptive 16,17-epiestriol fraction was confirmed by similar comparisons of the presumptive 16,17-epiestriol fraction and five derivatives thereof with reference 16,17-epiestriol and five corresponding derivatives each in three solvent systems; and chromatographic correspondences for two further derivatives were observed in one solvent system each.It is concluded that estriol and 16,17-epiestriol are normal constituents of hens' urine.

OPTIMIZATION OF THIN LAYER CHROMATOGRAPHY METHODS FOR SEPARATION AND IDENTIFICATION OF ANTIDEPRESSANTS IN THEIR MIXTURE

2014 ◽  
Vol 21 (1) ◽  
pp. 11-15
Author(s):  
Daiva Kazlauskienė ◽  
Guoda Kiliuvienė ◽  
Palma Nenortienė ◽  
Giedrė Kasparavičienė ◽  
Ieva Matukaitytė
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Solvent System ◽  
Ammonia Solution ◽  
Relative Standard ◽  
Rf Values ◽  
Solvent Systems ◽  
Paroxetine Hydrochloride ◽  
Fluvoxamine Maleate ◽  
Layer Chromatography

By conducting the toxicological analysis it is meaningful to determine the analytical system that could identify simultaneously several medicinal preparations quickly and precisely. The purpose of this work was to create and validate the method of thin-layer chromatography that would be suitable to separate the components of antidepressant mixture (amitriptyline hydrochloride, paroxetine hydrochloride, sertraline hydrochloride, fluvoxamine maleate and buspirone hydrochloride) and to identify them. The system was validated with regard to the sensitivity, repetition of data, resistance and particularity. The solvent systems with potential of high separation of components in their mixture were created: acetonitrile, methanol, ammonia solution 25 percent (85:10:5); acetonitrile, methanol, ammonia solution 25 percent (75:20:5); dichlormethane, 1,4-dioxane, ammonia solution 25 percent (50:45:5); dichlormethane, 1,4-dioxane, ammonia solution 25 percent (42:55:3); trichlormethane, 1,4-dioxane, ammonia solution 25 percent (25:70:5); trichlormethane, 1,4-dioxane, ammonia solution 25 percent (60:36:4). One of the most suitable solvent systems for separation of the analyzed mixture (sertraline, amitriptyline, paroxetine, buspirone, fluvoxamine) was determined – acetonitrile, methanol, ammonia solution 25 percent (85:10:5). When this solvent system was used, the average Rf values of the analyzed compounds differed the most. Validation was conducted – the relative standard deviation (RSD, percent) of the average Rf value of the analyzed compounds varied from 0,6 to 1,8 percent and did not exceed the permissible error of 5 percent. The sensitivity of methodology was determined by assessing the intensity of the mixture’s spots on the chromatographic plate. The detection limit of buspirone was 0,0012 µg; sertraline – 0,0008 µg; amitriptyline – 0,0004 µg; fluvoxamine – 0,0004 µg; paroxetine – 0,0008 µg. The resistance of results to the changed conditions – it was determined that when the amounts of the solvents acetonitrile and methanol were increased or decreased to two milliliters, the average Rf values of the analyzed compounds did not change statistically significantly

Fluorinated tricyclic neuroleptics with prolonged action: 8-Methoxy, 8-ethoxy, 8-ethylthio and 8-hydroxy derivatives of 3-fluoro-10-(4-methylpiperazino)-10,11-dihydrodibenzo[b,f]thiepin

1982 ◽  
Vol 47 (5) ◽  
pp. 1382-1391 ◽  
Author(s):  
Jiří Jílek ◽  
Josef Pomykáček ◽  
Jiřina Metyšová ◽  
Miroslav Protiva
Keyword(s):  
Acetic Acid ◽  
Polyphosphoric Acid ◽  
Prolonged Action ◽  
Substitution Reactions ◽  
Methoxy Derivative ◽  
Chloro Derivatives ◽  
Boron Tribromide ◽  
Derivatives Of ◽  
Central Depressant ◽  
Boiling Toluene

Acids IIa-c were prepared by reactions of (4-fluoro-2-iodophenyl)acetic acid with 4-methoxythiophenol, 4-ethoxythiophenol and 4-(ethylthio)thiophenol and cyclized with polyphosphoric acid in boiling toluene to dibenzo[b,f]thiepin-10(11H)-ones IIIa-c. Reduction with sodium borohydride afforded the alcohols IVa-c which were treated with hydrogen chloride and gave the chloro derivatives Va-c. Substitution reactions with 1-methylpiperazine resulted in the title compounds Ia-c out of which the methoxy derivative Ia was transformed by demethylation with boron tribromide to the phenol Id. Compounds Ia-d are very potent neuroleptics exhibiting a clear prolongation of the central depressant and some prolongation of the cataleptic activity.

ChemInform Abstract: DIHALO DERIVATIVES OF NAPHTHOSTYRIL-N-ACETIC ACID

1978 ◽  
Vol 9 (34) ◽  
Author(s):  
A. P. KARISHIN ◽  
A. A. PECHKA ◽  
N. F. GRINEVA
Keyword(s):  
Acetic Acid ◽  
Derivatives Of

scholarly journals Tubular Electrospun Vancomycin-Loaded Vascular Grafts: Formulation Study and Physicochemical Characterization

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2073
Author(s):  
Rossella Dorati ◽  
Enrica Chiesa ◽  
Mariella Rosalia ◽  
Silvia Pisani ◽  
Ida Genta ◽  
...  
Keyword(s):  
Methylene Chloride ◽  
Physicochemical Characterization ◽  
Fiber Surface ◽  
Solvent System ◽  
Burst Release ◽  
Sem Images ◽  
Composition And Structure ◽  
Medical Healthcare ◽  
Local Release ◽  
Preformulation Study

This work aimed at formulating tubular grafts electrospun with a size < 6 mm and incorporating vancomycin as an antimicrobial agent. Compared to other papers, the present study succeeded in using medical healthcare-grade polymers and solvents permitted by ICH Topic Q3C (R4). Vancomycin (VMC) was incorporated into polyester synthetic polymers (poly-L-lactide-co-poly-ε-caprolactone and poly lactide-co-glycolide) using permitted solvents; moreover, a surfactant was added to the formulation in order to avoid the precipitation of VMC on fiber surface. A preliminary preformulation study was carried out to evaluate solubility of VMC in different aqueous and organic solvents and its stability. To reduce size of fibers and their orientation, we studied a solvent system based on methylene chloride and acetone (DCM/acetone), at different ratios (80:20, 70:30, and 60:40). Considering conductivity of solutions and their spinnability, solvent system at a 80:20 ratio was selected for the study. SEM images demonstrated that size of fibers, their distribution, and their orientation were affected by the incorporation of VMC and surfactant into polymer solution. Surfactant allowed for the reduction of precipitates of VMC on fiber surface, which are responsible of the high burst release in the first six hours; the release was mainly dependent on graft structure porosity, number of pores, and graft absorbent capability. A controlled release of VMC was achieved, covering a period from 96 to 168 h as a function of composition and structure; the concentration of VMC was significantly beyond VMC minimum inhibitory concentration (MIC, 2 ug/mL). These results indicated that the VMC tubular electrospun grafts not only controlled the local release of VMC, but also avoided onset of antibiotic resistance.

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