Acetic Anhydride-pyridine Mixture Research Articles

Synthesis of Mesoionic 1-aryl-4-(phenyl/p-chlorophenyl)imidazo[2,1-b]thiazol-4-ones and Study of their Monoamine Oxidase, Succinate Dehydrogenase Inhibitory, Anti-convulsant, and Antibacterial Activity

1-Aryl-2-mercapto-4-(phenyl/p-chlorophenyl)imidazoles (Ia-j) were condensed with monochloroacetic acid to give 1-aryl-4-(phenyl/p-chlorophenyl)imidazo-2-mercaptoacetic acid (IIa-j). These acids were subsequently cyclized with an acetic anhydride-pyridine mixture to give a new fused ring mesoionic 1-aryl-4-(phenyl/p-chlorophenyl)imidazo[2,1-b]thiazol-1-3-ones (IIIa-j). These compounds possess AID50 values ranging from 500 to 1000 mg kg-1, inhibit monoamineoxidase (32-68%), and succinate dehydrogenase (28-55%) in vitro at a concentration of 2×10-4 M, and provide 20-60% protection against pentylenetetrazole induced convulsions in mice.

Gas chromatographic–mass spectrometric determination of azithromycin in biological fluids

Azithromycin monohydrate is an antibiotic, which belongs to the category of macrolide antibiotics. It is used for an effective antibiotic for the treatment of sexually transmitted diseases, upper and lower respiratory tract infections and skin structure infections. A gas chromatographic–mass spectrometric (GC–MS) method is described for the determination of azithromycin monohydrate residue in biological fluids. This method allows detection of residual azithromycin (AZM) in biological fluids by using single-ion monitoring (SIM). The confirmation by a full-scan electron impact (EI) mass spectrum is possible if residual level in a sample is >5 μg/mL. AZM is extracted with chloroform from a sample and cleaned up by n-hexane washing followed by partition between chloroform and phosphate buffer solution. The cleaned up extract is acetylated in acetic anhydride–pyridine mixture (1:2) at room temperature. The reaction mixture is injected into the GC–MS apparatus, and the detection has been conducted using SIM at m/z 200. The detection limit is 2 μg/mL. This proposed method could be successfully applied to the drug analysis in the forensic laboratories as well as in the toxicological laboratories.

Synthesis and Antimicrobial Activity of Some New 1,3-Diphenylpyrazoles Bearing Pyrimidine, Pyrimidinethione, Thiazolopyrimidine, Triazolopyrimidine, Thio-and Alkylthiotriazolop-Yrimidinone Moieties at the 4-Position

1,3-diphenyl-1H-pyrazole-4-carboxaldehyde (1) reacted with ethyl cyanoacetate and thiourea to give the pyrimidinethione derivative 2. The reaction of 2 with some alkylating agents gave the corresponding thioethers 3a–e and 7. Thione 2 was cyclized to 5 and 6 upon a reaction with chloroacetic acid and with benzaldehyde, respectively. Thioether 3c was cyclized to 4 upon boiling with sodium acetate in ethanol, and 7 was cyclized to 8 upon boiling in an acetic anhydride-pyridine mixture. The hydrazino derivative 9 was prepared either by boiling 2 and/or 3a with hydrazine. The reaction of 9 with nitrous acid, acetylacetone, triethyl orthoformate, acetic anhydride, and carbon disulfide gave 10–14. The alkylation of 14 with ethyl iodide, phenacyl bromide, and ethyl chloroacetate afforded the alkythiotriazolo pyrimidinone derivatives 15a–c. The dialkyl derivative 16 was produced upon the treatment of 2 with two equivalents of ethyl iodide. Boiling 16 with hydrazine afforded the hydrazino 17. The reaction of 17 with nitrous acid, carbon disulfide, ethyl cyanoacetate, ethyl acetoacetae, and phenacyl bromide gave 18–22, respectively. Some of the newly obtained compounds were tested for their antibacterial and antifungal activities.

Furan Ring Opening Reactions of 5-Hydroxy-2,3-dihydrobenzo[b]furans

A furan ring opening of benzo[b]furans (1a-c) under acetylation and methylation conditions was carried out. The reaction of these heterocycles with acetic anhydride-pyridine mixture afforded the corresponding 1,4-disubstituted buta-1,3-dienes (3a-c). Compound (3c) reacts with dimethyl sulfate under basic conditions to give 1-methoxy-4-(3,6-dimethoxy-2-nitrophenyl)-buta-1,3-diene (5) in 95 % yield. Some evidences on the participation of carbanion intermediates and a possible reaction course for the furan ring opening of heterocycles (1a-c) are presented

Gas Chromatographic/Mass Spectrometric Determination of Erythromycin in Beef and Pork

Abstract A gas chromatographic/mass spectrometric (GC/MS) method is described for the determination of residual erythromycin in beef and pork. This method allows detection and quantitation of residual erythromycin in beef and pork by using single-ion monitoring; confirmation by a full scan electron impact mass spectrum is possible if residual level in a sample is ≥ 1 ppm. Erythromycin is extracted with methanol from a sample and cleaned up by n-hexane washing followed by partition between chloroform and phosphate buffer solution. The cleaned up extract is chromatographed on a silica gel column, acid hydrolyzed, and acetylated in acetic anhydride-pyridine mixture (1 + 2) at room temperature. The reaction mixture is injected into the GC/MS apparatus, and detection and quantitation are conducted using single-ion monitoring at m/z 200. The recoveries (CV, %) at 1 and 0.1 ppm fortification levels are 86% (2.7%) and 72% (7.7%), and the detection limit is 0.01 ppm.

HIGH TENACITY AND HIGH MODULUS FIBERS FROM WHOLLY AROMATIC POLYIMIDES

Poly (amic-acids) were synthesized from pyromellitic dianhydride (PMDA) and aromatic diamines, of which the resultant C-N bonds are coaxial and oppositely directed (rigid diamines), using Nmethylpyrrolidone as polymerization solvent. Random copolymers composed of rigid diamine, PMDA and 3, 3′, 4, 4′-diphenylethertetracarboxylic dianhydride (DTDA) were also synthesized. These poly (amic-acids) were partially imidized by adding an appropriate amount of acetic anhydride (15_??_30 mole% based on amic-acid unit) into their solutions and then wet-spun, since it was found that partially imidized polymer solutions gave more transparent and void-free coagulated fibers than poly (amic-acid) solutions as polymerized. These fibers were then chemically converted to polyimides by immersing them in an acetic anhydride-pyridine mixture and heat-drawn.Relatively lower crystalline polyimides such as polypyromellitimides of aromatic diamines bearing chlorine substituent on the nuclei or random copolyimides had better drawability and gave fibers having higher tensile strength than higher crystalline polymers. For example, poly [2, 2′-dichloro-4, 4′-biphenylene/p-phenylene (70/30) pyromellitimide] gave a fiber having tenacity (T) 16.3g/d, elongation (E) 2.0% and initial modulus (Mi) 960g/d. Another random copolymer composed of benzidine/PMDA/DTDA (100/40/60) yielded a fiber with the following tensile properties: T 19.7g/d, E 1.7% and Mi 1310g/d.

Synthesis of potential antimicrobial agents from maltose. Part II. Partial conversion of maltose into cyclohexane derivatives.

5, 6-Unsaturated disaccharide derivative prepared from maltose via its 6-iodo derivative was treated with mercuric chloride, giving α-linked pseudodisaccharide in good yield, which contains cyclohexanonederivatives as constituents. On treatment with an acetic anhydride-pyridine mixture, the cyclohexanone constituents underwent β-elimination to be changed into a sole cyclohexenone moiety. Hydrogenation of the double bond between two carbon atoms and subsequent reductive amination of the carbonyl group gave aminocyclitol-containing pseudodisaccharides.

Determination of avermectins in plasma at nanogram levels using high-performance liquid chromatography with flourescence detection

An analytical method is described for the determination of the avermectins in plasma based upon high-performance liquid chromatography of flourescent derivatives of these compounds. The analyte is isolated by adsorption chromatography on Florisil, dehydrated in an acetic anhydride-pyridine mixture, and the fluorophore is further separated by chromatorgraphy on silica gel in advance of introduction into a reversed-phase system. This method, which can be applied to samples containing as little as 0.2 ng drug per ml, has an accuracy of 5% mean relative error and a precision of 8% relative standard deviation. A study and discussion of several factors which affect the analytical reaction are included.

Polyhydrazido acids and polyamidoimides with phenyl and cyclo-propane groups in chain

Properties of some polyhydrazido-acids in DMF and DMF-water solutions and their transformations under the influence of an acetic anhydride-pyridine mixture have been investigated. The polyhydrazido-acids have been obtained from the dihydrazide of (-) (1R,2R) trans-1,2 cyclopropanedicarboxylic acid and the dianhydride of pyromellitic (PHA-I) or 3,3′, 4,4′-diphenyloxide tetracarboxylic (PHA-II) acids and from a model hydrazido acid (MHA) prepared from the same hydrazide and phthalic anhydride. Cooperative changes in the molar rotation [π] and [η] were found in a mixed DMF-water solvent when the solvent composition was varied. These changes are related to intramolecular cooperative conformational transitions of the coil-compact particle type. PHA-II and MHA are used as examples showing that, under the influence of an acetic anhydride-pyridine mixture, cyclodehydration occurs via the formation of amidoisoimide which is isomerized further to amidoimide. When the acetic anhydride-pyridine mixture is present in large excess, the process ends with the acetylation of an amide group adjacent to the three-membered ring.

Gas-Liquid Chromatographic Identification and Determination of Alkanolamines. I. Application to Aerosol Hair Sprays

Abstract Alkanolamines, in the absence of water, are converted to the amide ester or triacetate with acetic anhydride-pyridine mixture. The amide ester or triacetate of the alkanolamine is determined by GLC on a column containing diethylene glycol succinate on Chromosorb G. Procedures for determining alkanolamines in various hair sprays are described; recoveries by the proposed procedure were satisfactory. The method developed was applied to the following 4 alkanolamines: 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, and triisopropanolamine.

Observations on the use of diazo-I-H-tetrazole and phenylglyoxal in protein histochemistry as applied to human gingiva.

A solution of diazo-1-H-tetrazole, freshly prepared by the diazotization of 5-amino-1-H-tetrazole under conditions to avoid explosion, was adjusted to pH 8.8, diluted (1∶1 or 1∶9) with 0.67 M bicarbonate buffer, pH 8.8, and used immediately as a histochemical reagent for demonstrating histidine, tryptophan, and tyrosine residues in deparaffinized sections of frozen-dried human gingiva, rat abdominal skin, and mouse larynx fixed in modified Newcomer's solution. Diazo-1-H-tetrazole reacted histochemically like other diazonium coupling reagents in common use, except that in sections pretreated with bromoacetic acid at pH 7, diazo-1-H-tetrazole staining was increased, rather than decreased as expected. Pretreatment with bromoacetic acid also increased staining in gingival sections exposed to an acetic anhydride-pyridine mixture and then reacted with diazo-1-H-tetrazole. Similarly, pretreatment with bromoacetic acid increased the intensity of Millon's reaction in gingival sections. Sections of human gingiva or mouse larynx pretreated with diazo-1-H-tetrazole stained less intensely with Biebrich Scarlet used respectively at pH 2.62 and 6.50. In test-tube experiments to check the specificity of diazo-1-H-tetrazole for amino acids, only histidine, tryptophan, and tyrosine gave solutions with colours visually distinguishable from the buffer blank. In similar tests a solution of ribonuclease A gave a colour like that given by histidine and tyrosine. Whereas pyridine failed to yield a colour with undiluted diazo-1-H-tetrazole reagent in test-tube experiments, gingival sections exposed to pyridine for 24 hr stained more intensely with diazo-1-H-tetrazole, but diazo-1-H-tetrazole staining of abdominal skin sections was not altered by prior treatment with pyridine. Phenylglyoxal, used as a 1.5% w/v solution inN-ethylmorpholine-acetate buffer (0.2 M acetate) pH 8, blocked the Sakaguchi reaction in human gingival sections. Pretreatment with phenylglyoxal also led to a reduction in their staining by Biebrich Scarlet at pH 2.62, dinitrofluorobenzene, or diazo-1-H-tetrazole. In addition the dimethylaminobenzaldehyde nitrite reaction for tryptophan was reduced. Phenylglyoxal blockade of arginine residues in gingival sections was labile to 1% acetic acid containing 0.05 M choline chloride after 60 min; but in test-tube experiments extending over 320 min, di(phenylglyoxal)-l-arginine hydrochloride was more stable in this acetic acid-choline solution than in water. It is suggested that after treatment of gingival sections with bromoacetic acid at pH 7.0, additional tyrosine residues become available for reaction with diazo-1-H-tetrazole. Pyridine is thought to remove ‘bound lipid’ from gingival epithelium, thereby exposing protein residues reactive with diazo-1-H-tetrazole. The use of diazo-1-H-tetrazole and phenylglyoxal for characterizing amino acid residues of gingival proteins responsible for anionic dye binding is discussed.

SOME ORGANIC MATTER-CLAY MINERAL RELATIONSHIPS IN FOUR ALBERTA SOIL PROFILES

Four soil profiles were characterized as to nitrogen, carbon, clay and polysaccharide content. Direct extractions of the soils were also made with 1N HF-HCl and an acetic anhydride-pyridine mixture and 1.0 N NaOH. Two NaOH extractions of the lower horizons, with and without auxiliary acidic treatments between the first and second to facilitate the release of organic matter, were used to evaluate certain clay-organic matter relationships.Polysaccharide content and the C:N ratios generally decreased with depth in all soils. Of the direct extractants of organic matter NaOH was the most efficient and HF-HCl and acetic anhydride-pyridine solutions were generally ineffective. However, some accumulation of HF-HCl soluble organic matter was noted in the A2 and B2 horizons of two of the soils. The organic solvents were most effective in removing organic matter from the B2 horizons.The use of auxiliary treatments (HF-HCl, H2SO4 or both) between the first and second NaOH extractions greatly enhanced the release of the organic matter by the second NaOH extraction from the B2, Bsa and C horizons of these soils. With the exception of the A2 horizons a combined HF-HCl 2nd H2SO4 pretreatment was superior to HF-HCl or H2SO4 used alone. The retentive capacity of the clay for soil organic matter was greatest in the C and Bsa horizons as determined by the intensity of the extracting conditions necessary to effect solubilization of the organic matter into the second alkali solutions.

Microdeterminination of Hydroxyl Content of Organic Compounds - Acetic Anhydride-Pyridine Mixture as Reagent

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicrodeterminination of Hydroxyl Content of Organic Compounds - Acetic Anhydride-Pyridine Mixture as ReagentJack Petersen, Kenneth Hedberg, and Bert ChristensenCite this: Ind. Eng. Chem. Anal. Ed. 1943, 15, 3, 225–226Publication Date (Print):March 1, 1943Publication History Published online1 May 2002Published inissue 1 March 1943https://doi.org/10.1021/i560115a023RIGHTS & PERMISSIONSArticle Views182Altmetric-Citations31LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (268 KB) Get e-Alerts