The interaction of formylporphyrins with weak CH-acids

2003 ◽  
Vol 07 (11) ◽  
pp. 761-765 ◽  
Author(s):  
Yurij V. Ishkov ◽  
Zinaida I. Zhilina ◽  
Ludmila P. Barday
Keyword(s):  
Perchloric Acid ◽  
Condensation Product ◽  
Free Base ◽  
Schmidt Reaction ◽  
Ch Acids ◽  
Iminium Salt

A series of 2(α,β-unsaturated-γ-keto)-5,10,15,20-tetraphenylporphyrins was obtained by condensation of 2-formyl-5,10,15,20-tetraphenylporphyrin with acetone, 1,4-diacetylbenzene, 2-acetylthiophene, acetylacetone and acetophenone according to the Claisen-Schmidt reaction. The condensation product with 1,4-diacetylbenzene could react similarly with another formyl derivative – quinoxalin-6-carboxaldehyde and 2-formyl-5,10,15,20-tetraphenylporphyrin. It is shown that this reaction passes through formation of iminium salt formylporphyrin in presence of free base piperidine and perchloric acid.

scholarly journals Novel Photosynthesis of 5,8a-dichloro-2-(4- Methoxyphenyl)-8ah-chromene from Its Chalcone Isomer And Ft-ir, 1 H And 13 C Nmr Spectroscopic Investigation

2020 ◽  
Vol 23 (2) ◽  
pp. 118-134
Author(s):  
Abdullah A. Yousif ◽  
Ghazwan F. Fadhil
Keyword(s):  
Aldol Condensation ◽  
Condensation Product ◽  
Xenon Lamp ◽  
Alcoholic Alkali ◽  
Schmidt Reaction ◽  
Flight Mass Spectrometry ◽  
13C Nuclear Magnetic Resonance ◽  
Ft Ir ◽  
Layer Chromatography ◽  
C Nmr

In the presence of alcoholic alkali, the base-catalyzed aldol condensation of equimolar quantities of substituted acetophenones and aldehydes to give good yields of condensation product. This reaction is known as the Claisen-Schmidt condensation. The Trans-3-(2,6-dichlorophenyl)-1-(4-methoxyphenyl)prop- 2-en-1-one (trans 2,6-methoxy chalcone) was synthesised by Clasien Schmidt reaction, then it exposed to the Xenon lamp to prepare the 5,8a-dichloro-2-(4-methoxyphenyl)-8aH-chromene (2,6-methoxy chromene). A number of techniques were used to characterise the mentioned two products such as, thin layer chromatography, FT-IR, 1H and 13C nuclear magnetic resonance, liquid chromatography/quadrupole time-of-flight mass spectrometry and elemental analysis (CHNO).

Stereoselective and Stereospecific Triflate Mediated Intramolecular Schmidt Reaction: Easy Access to Alkaloid Skeletons

2020 ◽  
Author(s):  
Lars Gnägi ◽  
Remo Arnold ◽  
Florence Giornal ◽  
Harish Jangra ◽  
Ajoy Kapat ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Easy Access ◽  
Chiral Alcohols ◽  
Schmidt Reaction ◽  
Salt Reduction ◽  
Iminium Salt ◽  
Whole Process ◽  
Structural Skeleton

The stereoselectivity and stereospecificity of the triflate mediated intramolecular Schmidt reaction of substituted 3-(1-azidocyclohexyl)propanol derivatives leading to octahydro-1<i>H</i>-pyrrolo[1,2-a]azepine, the structural skeleton of several important families of alkaloids such as the <i>Stemona</i> alkaloids, has been examined. The reaction involves an initial intramolecular S<sub>N</sub>2 reaction between the azide moiety and the triflate affording an intermediate spirocyclic aminodiazonoium salt that undergoes the expected 1,2-shift/N<sub>2</sub>-elimination followed by hydride mediated iminium salt reduction. Remarkably, chiral alcohols are converted to the azabicylic derivative with no or limited racemization. The initial asymmetric alcohol center controls the diastereoselectivity of the whole process leading to the formation of one out of the four possible diastereoisomers of disubstituted octahydro-1<i>H</i>-pyrrolo[1,2-a]azepine. The origin of the stereoselectivity is rationalized based on theoretical calculations. The concise synthesis of (–)-(<i>cis</i>)-3-propylindolizidine and (–)-(<i>cis</i>)-3-butyllehmizidine, two alkaloids found in the venom of workers of the ant <i>Myrmicaria melanogaster</i>, is reported.<br>

scholarly journals Stereochemical Control of the Triflate Mediated Intramolecular Schmidt Reaction

2020 ◽  
Author(s):  
Lars Gnägi ◽  
Florence Giornal ◽  
Harish Jangra ◽  
Ajoy Kapat ◽  
Erich Nyfeler ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Chiral Alcohols ◽  
Schmidt Reaction ◽  
Salt Reduction ◽  
Iminium Salt ◽  
Whole Process ◽  
Stereochemical Control ◽  
Structural Skeleton

The stereoselectivity of the triflate mediated intramolecular Schmidt reaction of substituted 3-(1-azidocyclohexyl)propanol derivatives leading to octahydro-1<i>H</i>-pyrrolo[1,2-a]azepine, the structural skeleton of several important families of alkaloids such as the <i>Stemona</i> alkaloids, has been examined. The reaction involves an initial intramolecular S<sub>N</sub>2 reaction between the azide moiety and the triflate affording an intermediate spirocyclic aminodiazonoium salt that undergoes the expected 1,2-shift/N<sub>2</sub>-elimination followed by hydride mediated iminium salt reduction. Remarkably, chiral alcohols are converted to the azabicylic derivative with no or limited racemization. The initial asymmetric alcohol center controls the diastereoselectivity of the whole process leading to the formation of one out of the four possible diastereoisomers of disubstituted octahydro-1<i>H</i>-pyrrolo[1,2-a]azepine. The origin of the stereoselectivity of is rationalized based on theoretical calculations.

scholarly journals Stereochemical Control of the Triflate Mediated Intramolecular Schmidt Reaction

2020 ◽  
Author(s):  
Lars Gnägi ◽  
Florence Giornal ◽  
Harish Jangra ◽  
Ajoy Kapat ◽  
Erich Nyfeler ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Chiral Alcohols ◽  
Schmidt Reaction ◽  
Salt Reduction ◽  
Iminium Salt ◽  
Whole Process ◽  
Stereochemical Control ◽  
Structural Skeleton

The stereoselectivity of the triflate mediated intramolecular Schmidt reaction of substituted 3-(1-azidocyclohexyl)propanol derivatives leading to octahydro-1<i>H</i>-pyrrolo[1,2-a]azepine, the structural skeleton of several important families of alkaloids such as the <i>Stemona</i> alkaloids, has been examined. The reaction involves an initial intramolecular S<sub>N</sub>2 reaction between the azide moiety and the triflate affording an intermediate spirocyclic aminodiazonoium salt that undergoes the expected 1,2-shift/N<sub>2</sub>-elimination followed by hydride mediated iminium salt reduction. Remarkably, chiral alcohols are converted to the azabicylic derivative with no or limited racemization. The initial asymmetric alcohol center controls the diastereoselectivity of the whole process leading to the formation of one out of the four possible diastereoisomers of disubstituted octahydro-1<i>H</i>-pyrrolo[1,2-a]azepine. The origin of the stereoselectivity of is rationalized based on theoretical calculations.

Extended Preservation of Iron for Transmission

1967 ◽  
Vol 25 ◽  
pp. 354-355
Author(s):  
E. P. Abrahamson II ◽  
M. W. Dumais
Keyword(s):  
Acid Solution ◽  
Perchloric Acid ◽  
Microscopy Study ◽  
Perchloric Acid Solution ◽  
Transmission Microscopy ◽  
Iron Base ◽  
Cold Stage

In a transmission microscopy study of iron and dilute iron base alloys, it was determined that it is possible to preserve specimens for extended periods of time. Our specimens were prepunched from 5 to 8 mil sheet to microscope size and annealed for several hours at 700°C. They were then thinned in a glacial acetic-12 percent perchloric acid solution using 10 volts and 20 milliamperes, at a temperature of 8 to 14°C.It was noted that by the use of a cold stage, the same specimen can be observed for periods up to one week without excess contamination. When removal of the specimen from the column becomes necessary, it was observed that a specimen may be kept for later observation in 1,2 dichloroethene or methanol for periods in excess of two weeks.

The Structure and Development of Microbodies in the Fat Body and other Tissues of an Insect (Calpodes Ethlius)

1970 ◽  
Vol 28 ◽  
pp. 148-149
Author(s):  
M. Locke ◽  
J. T. McMahon
Keyword(s):  
Electron Microscopy ◽  
Liquid Crystals ◽  
Fat Body ◽  
Competitive Inhibitor ◽  
Dense Core ◽  
Urate Oxidase ◽  
Blood Proteins ◽  
Free Base ◽  
The Core ◽  
The Matrix

The fat body of insects has always been compared functionally to the liver of vertebrates. Both synthesize and store glycogen and lipid and are concerned with the formation of blood proteins. The comparison becomes even more apt with the discovery of microbodies and the localization of urate oxidase and catalase in insect fat body.The microbodies are oval to spherical bodies about 1μ across with a depression and dense core on one side. The core is made of coiled tubules together with dense material close to the depressed membrane. The tubules may appear loose or densely packed but always intertwined like liquid crystals, never straight as in solid crystals (Fig. 1). When fat body is reacted with diaminobenzidine free base and H2O2 at pH 9.0 to determine the distribution of catalase, electron microscopy shows the enzyme in the matrix of the microbodies (Fig. 2). The reaction is abolished by 3-amino-1, 2, 4-triazole, a competitive inhibitor of catalase. The fat body is the only tissue which consistantly reacts positively for urate oxidase. The reaction product is sharply localized in granules of about the same size and distribution as the microbodies. The reaction is inhibited by 2, 6, 8-trichloropurine, a competitive inhibitor of urate oxidase.

Characterization of Chemical Impurities in Glutaraldehyde

1975 ◽  
Vol 33 ◽  
pp. 620-621
Author(s):  
B. J. Grenon ◽  
A. J. Tousimis
Keyword(s):  
Glutaric Acid ◽  
Spectroscopic Analysis ◽  
Aldol Condensation ◽  
Condensation Product ◽  
Amorphous Solid ◽  
Water Soluble ◽  
Impurity Component ◽  
Chemical Impurities ◽  
Soluble Liquid

Ever since the introduction of glutaraldehyde as a fixative in electron microscopy of biological specimens, the identification of impurities and consequently their effects on biologic ultrastructure have been under investigation. Several reports postulate that the impurities of glutaraldehyde, used as a fixative, are glutaric acid, glutaraldehyde polymer, acrolein and glutaraldoxime.Analysis of commercially available biological or technical grade glutaraldehyde revealed two major impurity components, none of which has been reported. The first compound is a colorless, water-soluble liquid with a boiling point of 42°C at 16 mm. Utilizing Nuclear Magnetic Resonance (NMR) spectroscopic analysis, this compound has been identified to be — dihydro-2-ethoxy 2H-pyran. This impurity component of the glutaraldehyde biological or technical grades has an UV absorption peak at 235nm. The second compound is a white amorphous solid which is insoluble in water and has a melting point of 80-82°C. Initial chemical analysis indicates that this compound is an aldol condensation product(s) of glutaraldehyde.

Free‐base tetra‐arylphthalocyanines for dye‐sensitised nanostructured solar cell applications

2001 ◽  
Vol 5 (8) ◽  
pp. 609-616 ◽  
Author(s):  
Viviane Aranyos ◽  
Johan Hjelm ◽  
Anders Hagfeldt ◽  
Helena Grennberg
Keyword(s):  
Solar Cell ◽  
Free Base
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