THE CHEMICAL STABILITY OF THE S-METHYL XANTHATES OF SOME SIMPLE ALCOHOLS

1956 ◽  
Vol 34 (9) ◽  
pp. 1302-1314 ◽  
Author(s):  
D. L. Vincent ◽  
C. B. Purves
Keyword(s):  
Hydrogen Peroxide ◽  
Methyl Ester ◽  
Methyl Iodide ◽  
Chemical Stability ◽  
Periodic Acid ◽  
High Yield ◽  
Methylating Agents ◽  
First Time ◽  
Oxygen Atoms

n-Octadecyl S-methyl xanthate, m.p. 38–39°, and n-hexadecyl S-methyl xanthate, m.p. 28–28.5°, were prepared for the first time, and were used to study the behavior of the S-methyl xanthate group toward reagents commonly used in research on carbohydrates. Although stable to some conditions of acetylation, hydrolysis, and methanolysis, the S-methyl xanthate group was destroyed by all methylating agents tried, with the exception of nitrosomethylurethane. The latter reagent converted a sodium xanthate salt in high yield to the S-methyl ester. Octadecyl and hexadecyl S-methyl xanthates when oxidized with hydrogen peroxide yielded crystalline substances of composition C20H40O4S2 and C18H36O4S2, respectively, whose structures were not determined. These substances each contained three additional oxygen atoms. Various attempts to estimate the S-methyl xanthate group by oxidation with bromine or periodic acid, or by reduction to methyl iodide, were unsuccessful.

scholarly journals Simultaneous demonstration of glycogen and protein in glycosomes of cardiac tissue.

1981 ◽  
Vol 29 (1) ◽  
pp. 4-8 ◽  
Author(s):  
K Rybicka
Keyword(s):  
Hydrogen Peroxide ◽  
Cardiac Tissue ◽  
Periodic Acid ◽  
Uranyl Acetate ◽  
Cardiac Conduction ◽  
Cellular Structures ◽  
Lead Citrate ◽  
En Bloc ◽  
First Time

Cardiac conduction fibers fixed either in glutaraldehyde and OsO4 or treated additionally en bloc with uranyl acetate were studied in order to demonstrate the structure of glycosomes (protein-glycogen complex). Sections were stained histochemically by periodic acid-thiosemicarbazide-silver proteinate (PA--TSC--SP) for glycogen followed by uranyl acetate and lead citrate (U-Pb) for protein. In control sections periodic acid was replaced by hydrogen peroxide (H2O2). Glycogen appeared in all sections stained by PA-TSC-SP. Protein was poorly contrasted in periodic acid treated histochemical sections taken from fixed in glutaraldehyde and OsO4. Simultaneous staining of glycogen and protein was achieved in sections of tissue treated en bloc with uranyl acetate. This treatment revealed two classes of glycosomes: 1) glycosomes deposited freely in the cytoplasm whose structure was disintegrated after treatment with uranyl acetate: 2) glycosomes associated with other cellular structures that remained intact. Staining of glycogen and protein in the same section demonstrated for the first time the structure of intact glycosomes.

scholarly journals Investigating the effectiveness of classical and eco-friendly approaches for synthesis of dialdehydes from organic dihalides

2019 ◽  
Vol 8 (1) ◽  
pp. 635-648 ◽  
Author(s):  
Muhammad Faisal ◽  
Mukhtiar Ahmed ◽  
Sarwat Hussain ◽  
Fayaz Ali Larik ◽  
Aamer Saeed
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Synthesis ◽  
Vanadium Pentoxide ◽  
Sodium Periodate ◽  
Periodic Acid ◽  
Research Work ◽  
High Yield ◽  
Synthetic Approach ◽  
Kornblum Oxidation ◽  
Excellent Selectivity

Abstract Monoaldehydes and dialdehydes are parts of millions of compounds and are extremely versatile intermediates. For the synthesis of monoaldehydes, one impressive approach to date, because of its excellent selectivity, high yield and stability towards over-oxidation and over-reduction, is the oxidation of organic monohalides. Numerous monohalides oxidation based methodologies to afford monoaldehydes are disclosed in literature. In this research work, twelve well-known approaches (well-documented for synthesis of monoaldehydes from monohalides) are investigated for their effectiveness towards synthesis of organic dialdehydes from organic dihalides. The classical approaches under investigation include modified Sommelet oxidation, Kröhnke oxidation, sodium periodate-mediated oxidative protocol, manganese dioxide-based oxidative approach, Kornblum oxidation and Hass-Bender oxidation. The eco-friendly approaches under observation include periodic acid-based IL protocol, periodic acid in vanadium pentoxide-mediated IL method, hydrogen peroxide in vanadium pentoxide-based approach, hydrogen peroxide-mediated IL methodology, IBX-assisted IL protocol and bismuth nitrate-promoted IL technique. In this investigation yield, overoxidation, eco-friendliness, cost-effectiveness and recyclability are the main parameters which are under examination. Hopefully, this research will help chemists in carrying out routine operations in organic synthesis and will also be fruitful to select finest synthetic approach, develop further new transformational methodologies and improve current transformational approaches for the synthesis of dialdehydes.

Ozonolysis of podocarpic acid

1970 ◽  
Vol 48 (7) ◽  
pp. 1105-1113 ◽  
Author(s):  
R. A. Bell ◽  
M. B. Gravestock
Keyword(s):  
Hydrogen Peroxide ◽  
Methyl Ester ◽  
Methylene Chloride ◽  
Nuclear Overhauser Effect ◽  
High Yield ◽  
Keto Acid ◽  
Dioic Acid ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Work Up

Low temperature ozonolysis of methyl podocarpate in methanol – methylene chloride results in the formation in high yield of 8β-hydroperoxy-8α-hydroxy-(13 → 17)-pentanorlabd-9(11)-en-12,19-dioic acid 19-methyl ester 8 → 12-lactone 4. Ozonolysis followed by hydrogen peroxide work-up gives the lactone-acid 14a, whilst ozonolysis followed by reduction with sodium borohydride gives keto-acid 3a and lactones 16 and 17 derived from peroxide 4 together with δ-lactone 19 possessing all 18 carbon atoms of methyl podocarpate. The lactone 16 is shown to possess an 8β-configuration by application of the nuclear Overhauser effect.

The Smoulder Stream of Cigarettes / Zur Kenntnis des Glimmstromes von Cigaretten

1965 ◽  
Vol 3 (2) ◽  
Author(s):  
F. Seehofer ◽  
W. Schulz
Keyword(s):  
Moisture Content ◽  
Spatial Position ◽  
High Yield ◽  
Physical Conditions ◽  
Moisture Contents ◽  
Cigarette Paper ◽  
First Time

AbstractThe phenomenon of the smoulder stream flowing through the cigarette during smouldering and during the puff intervals is demonstrated for the first time and its dependence upon physical conditions is examined. The volume of the smoulder stream can amount up to 180 ml per cigarette. Increasing draw resistance of the cigarette and augmenting moisture content of the tobacco as well as perforation of the cigarette paper have a decreasing effect on volume and velocity of the smoulder stream. The porosity of the cigarette paper has no perceptible influence. The spatial position of the cigarette affects volume and velocity of the smoulder stream. The influence exercised by the smoulder stream on the yields of total condensate, nicotine, phenols, aldehydes, and acroleine when the cigarette tip is open during the puff intervals is determined. When the moisture contents of the tobacco were extremely high, yield decreases reaching 50 % could be observed.

Iridium-Catalyzed Silylation of C-H bonds in Unactivated Arenes: A Sterically-Encumbered Phenanthroline Ligand Accelerates Catalysis Enabling New Reactivity

2019 ◽  
Author(s):  
Caleb Karmel ◽  
Zhewei Chen ◽  
John Hartwig
Keyword(s):  
High Activity ◽  
Functional Group ◽  
Activity Analysis ◽  
High Reactivity ◽  
High Yield ◽  
Phen Ligand ◽  
Mechanistic Studies ◽  
Phenanthroline Ligand ◽  
First Time ◽  
New System

We report a new system for the silylation of aryl C-H bonds. The combination of [Ir(cod)(OMe)]<sub>2</sub> and 2,9-Me<sub>2</sub>-phenanthroline (2,9-Me<sub>2</sub>phen) catalyzes the silylation of arenes at lower temperatures and with faster rates than those reported previously, when the hydrogen byproduct is removed, and with high functional group tolerance and regioselectivity. Inhibition of reactions by the H<sub>2</sub> byproduct is shown to limit the silylation of aryl C-H bonds in the presence of the most active catalysts, thereby masking their high activity. Analysis of initial rates uncovered the high reactivity of the catalyst containing the sterically hindered 2,9-Me<sub>2</sub>phen ligand but accompanying rapid inhibition by hydrogen. With this catalyst, under a flow of nitrogen to remove hydrogen, electron-rich arenes, including those containing sensitive functional groups, undergo silylation in high yield for the first time, and arenes that underwent silylation with prior catalysts react over much shorter times with lower catalyst loadings. The synthetic value of this methodology is demonstrated by the preparation of key intermediates in the synthesis of medicinally important compounds in concise sequences comprising silylation and functionalization. Mechanistic studies demonstrate that the cleavage of the aryl C-H bond is reversible and that the higher rates observed with the 2,9-Me<sub>2</sub>phen ligand is due to a more thermodynamically favorable oxidative addition of aryl C-H bonds.

scholarly journals Bacterial cellulose spheroids as building blocks for 3D and patterned living materials and for regeneration

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Joaquin Caro-Astorga ◽  
Kenneth T. Walker ◽  
Natalia Herrera ◽  
Koon-Yang Lee ◽  
Tom Ellis
Keyword(s):  
Bacterial Cellulose ◽  
Building Blocks ◽  
Genetically Engineered ◽  
High Yield ◽  
Synthetic Materials ◽  
Chemical Inputs ◽  
First Time ◽  
3D Shapes ◽  
Promising Avenue ◽  
Living Materials

AbstractEngineered living materials (ELMs) based on bacterial cellulose (BC) offer a promising avenue for cheap-to-produce materials that can be programmed with genetically encoded functionalities. Here we explore how ELMs can be fabricated in a modular fashion from millimetre-scale biofilm spheroids grown from shaking cultures of Komagataeibacter rhaeticus. Here we define a reproducible protocol to produce BC spheroids with the high yield bacterial cellulose producer K. rhaeticus and demonstrate for the first time their potential for their use as building blocks to grow ELMs in 3D shapes. Using genetically engineered K. rhaeticus, we produce functionalized BC spheroids and use these to make and grow patterned BC-based ELMs that signal within a material and can sense and report on chemical inputs. We also investigate the use of BC spheroids as a method to regenerate damaged BC materials and as a way to fuse together smaller material sections of cellulose and synthetic materials into a larger piece. This work improves our understanding of BC spheroid formation and showcases their great potential for fabricating, patterning and repairing ELMs based on the promising biomaterial of bacterial cellulose.

scholarly journals A Novel and Efficient High-Yield Method for Preparing Bacterial Ghosts

Toxins ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 420
Author(s):  
Yi Ma ◽  
Liu Cui ◽  
Meng Wang ◽  
Qiuli Sun ◽  
Kaisheng Liu ◽  
...  
Keyword(s):  
Large Scale ◽  
Expression System ◽  
High Yield ◽  
Wild Type ◽  
High Quality ◽  
Efficient Protection ◽  
Bacterial Ghosts ◽  
Cell Envelopes ◽  
Extracellular Structures ◽  
First Time

Bacterial ghosts (BGs) are empty cell envelopes possessing native extracellular structures without a cytoplasm and genetic materials. BGs are proposed to have significant prospects in biomedical research as vaccines or delivery carriers. The applications of BGs are often limited by inefficient bacterial lysis and a low yield. To solve these problems, we compared the lysis efficiency of the wild-type protein E (EW) from phage ΦX174 and the screened mutant protein E (EM) in the Escherichia coli BL21(DE3) strain. The results show that the lysis efficiency mediated by protein EM was improved. The implementation of the pLysS plasmid allowed nearly 100% lysis efficiency, with a high initial cell density as high as OD600 = 2.0, which was higher compared to the commonly used BG preparation method. The results of Western blot analysis and immunofluorescence indicate that the expression level of protein EM was significantly higher than that of the non-pLysS plasmid. High-quality BGs were observed by SEM and TEM. To verify the applicability of this method in other bacteria, the T7 RNA polymerase expression system was successfully constructed in Salmonella enterica (S. Enterica, SE). A pET vector containing EM and pLysS were introduced to obtain high-quality SE ghosts which could provide efficient protection for humans and animals. This paper describes a novel and commonly used method to produce high-quality BGs on a large scale for the first time.

Fast one-step synthesis of N-doped carbon dots by pyrolyzing ethanolamine

2014 ◽  
Vol 2 (36) ◽  
pp. 7477-7481 ◽  
Author(s):  
Xinwei Dong ◽  
Yanjie Su ◽  
Huijuan Geng ◽  
Zhongli Li ◽  
Chao Yang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Dots ◽  
High Yield ◽  
One Step ◽  
Doped Carbon Dots

N-doped CDs can be obtained directly with high yield by pyrolyzing ethanolamine in air within just 7 minutes with the assistance of hydrogen peroxide.

scholarly journals Cyclic Lipopeptides with Herbicidal and Insecticidal Activities Produced by Bacillus clausii DTM1

2015 ◽  
Vol 10 (12) ◽  
pp. 1934578X1501001 ◽  
Author(s):  
Da-Le Guo ◽  
Bo Wan ◽  
Shi-Ji Xiao ◽  
Sarah Allen ◽  
Yu-Cheng Gu ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Natural Product ◽  
Fermentation Broth ◽  
Cyclic Lipopeptides ◽  
Bacillus Clausii ◽  
Cyclic Lipopeptide ◽  
Lipopeptide Biosurfactants ◽  
First Time ◽  
Insecticidal Activities

Seven cyclic lipopeptide biosurfactants (1–7) were isolated for the first time from the fermentation broth of endophytic Bacillus clausii DTM1 and were identified as anteisoC13[Val7] surfactin-(L-Glu)-O-methyl-ester (1), anteisoC12[Val7] surfactin (2), anteisoC15[Val7] surfactin (3), isoC14[Leu7] surfactin (4), anteisoC12[Leu7] surfactin (5), nC13[Leu7] surfactin (6), and anteisoC14[Leu7] surfactin-(L-Glu)-O-methyl-ester (7); 1 has not been isolated before as a natural product from any source. Plate-based herbicide and insecticide bioassays showed that all compounds exhibited interesting insecticidal and herbicidal activities.

The application of inexpensive and synthetic simple electrocatalyst CuFe-MoC@NG in immunosensor

The Analyst ◽  
2021 ◽  
Author(s):  
Lisha Mei ◽  
Wentang Zhao ◽  
Yiju Song ◽  
Li Zhang ◽  
Mengmeng Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Precious Metal ◽  
Doped Graphene ◽  
One Step ◽  
Metal Materials ◽  
First Time

In this study, we used inexpensive and synthetic simple electrocatalysts replacement conventional precious metal materials to reduce hydrogen peroxide (H2O2). We first time developed N-doped graphene-coated CuFe@MoC using one-step calcination...

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