Influence of Reaction Conditions and Promoting Role of Ammonia Produced at Higher Temperature Conditions in Its Synthesis Process over Cs-Ru/MgO Catalyst

The methods of chemical structural alteration of small organic molecules by using microbes (fungi, bacteria, yeast, etc.) are gaining tremendous attention to obtain structurally novel and therapeutically potential leads. The regiospecific mild environmental friendly reaction conditions with the ability of novel chemical structural modification in compounds categorize this technique; a distinguished and unique way to obtain medicinally important drugs and their in vivo mimic metabolites with costeffective and timely manner. This review article shortly addresses the immense pharmaceutical importance of microbial transformation methods in drug designing and development as well as the role of CYP450 enzymes in fungi to obtain in vivo drug metabolites for toxicological studies.

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TBAI Catalyzed Electrochemical C-H Bond Activation of 2-arylated-N-methoxyamides for the Synthesis of Phenanthridinones

Synlett ◽

10.1055/a-1467-5585 ◽

2021 ◽

Author(s):

Kripa Subramanian ◽

Subhash L. Yedage ◽

Kashish Sethi ◽

Bhalchandra M. Bhanage

Keyword(s):

Electrochemical Method ◽

Bond Activation ◽

Supporting Electrolyte ◽

Bioactive Compound ◽

Reaction Conditions ◽

Redox Catalyst ◽

Synthetic Utility ◽

One Step ◽

Constant Potential

An electrochemical method for the synthesis of phenanthridinones via constant potential electrolysis (CPE) mediated by <i>n</i>-Bu<sub>4</sub>NI (TBAI) has been reported. The protocol is metal and oxidant free and proceeds with 100% current efficiency. Here TBAI plays the dual role of the redox catalyst as well as supporting electrolyte. The intramolecular C-H activation proceeds under mild reaction conditions and short reaction time via electrochemically generated amidyl radicals. The reaction has been scaled up to gram level showing its practicability and the synthetic utility and applicability of the protocol has been demonstrated by the direct one-step synthesis of the bioactive compound Phenaglaydon.

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N-Chlorinative Ring Contraction of 1,4-Dimethoxyphthalazines via a Bicyclization/Ring-Opening Mechanism

Synthesis ◽

10.1055/s-0040-1706639 ◽

2020 ◽

Author(s):

Jeong Kyun Im ◽

Ilju Jeong ◽

Jun-Ho Choi ◽

Won-jin Chung ◽

ByeongDo Yang ◽

...

Keyword(s):

Ring Opening ◽

Reaction Conditions ◽

Ring Contraction ◽

Silyl Group ◽

Favorskii Rearrangement ◽

Mechanistic Analysis ◽

Group A ◽

Overall Efficiency ◽

Trichloroisocyanuric Acid

AbstractAn unprecedented N-chlorinative ring contraction of 1,2-diazines was discovered and investigated with an electrophilic chlorinating reagent, trichloroisocyanuric acid (TCICA). Through optimization and mechanistic analysis, the assisting role of n-Bu4NCl as an exogenous nucleophile was identified, and the optimized reaction conditions were applied to a range of 1,4-dimethoxyphthalazine derivatives. Also, an improvement of overall efficiency was demonstrated by the use of a labile O-silyl group. A bicyclization/ring-opening mechanism, inspired by the Favorskii rearrangement, was proposed and supported by the DFT calculations. Furthermore, the efforts on scope expansion as well as the evaluation of other electrophilic promoters revealed that the newly developed ring contraction reactivity is a unique characteristic of 1,4-dimethoxyphthalazine scaffold and TCICA.

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Preparation and Characrization of Tic/C Composite Fiber by Chemical Vapor Deposition

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.455-456.935 ◽

2012 ◽

Vol 455-456 ◽

pp. 935-938

Author(s):

Hai Quan Wang

Keyword(s):

Chemical Vapor Deposition ◽

Carbon Fibers ◽

Vapor Deposition ◽

Chemical Vapor ◽

Composite Fiber ◽

Composite Fibers ◽

X Ray Diffraction ◽

Reaction Conditions ◽

Tic Particle ◽

Higher Temperature

- TiC/C composite fibers were prepared by vapor phase titanizing of the regular carbon fibers via chemical vapor deposition (CVD). The carbon fibers were titanized from the surface of the fiber to the core. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were applied to characterize the morphology and structure of the TiC/C composite fibers. The influences of CVD reaction conditions such as temperature and reaction time on the TiC particle size and the thickness of the deposited layer were investigated. Higher temperature and longer time resulted in the growth of bigger size of the TiC crystal particles, and the particle uniformity was also decreased.

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Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.12.254 ◽

2016 ◽

Vol 12 ◽

pp. 2588-2601 ◽

Cited By ~ 3

Author(s):

Vladimir A Stepchenko ◽

Anatoly I Miroshnikov ◽

Frank Seela ◽

Igor A Mikhailopulo

Keyword(s):

Purine Nucleoside Phosphorylase ◽

Reaction Conditions ◽

E Coli ◽

No Formation ◽

Structural Peculiarities ◽

Substrate Properties ◽

Nucleoside Phosphorylases ◽

Derivatives Of

The trans-2-deoxyribosylation of 4-thiouracil (4SUra) and 2-thiouracil (2SUra), as well as 6-azauracil, 6-azathymine and 6-aza-2-thiothymine was studied using dG and E. coli purine nucleoside phosphorylase (PNP) for the in situ generation of 2-deoxy-α-D-ribofuranose-1-phosphate (dRib-1P) followed by its coupling with the bases catalyzed by either E. coli thymidine (TP) or uridine (UP) phosphorylases. 4SUra revealed satisfactory substrate activity for UP and, unexpectedly, complete inertness for TP; no formation of 2’-deoxy-2-thiouridine (2SUd) was observed under analogous reaction conditions in the presence of UP and TP. On the contrary, 2SU, 2SUd, 4STd and 2STd are good substrates for both UP and TP; moreover, 2SU, 4STd and 2’-deoxy-5-azacytidine (Decitabine) are substrates for PNP and the phosphorolysis of the latter is reversible. Condensation of 2SUra and 5-azacytosine with dRib-1P (Ba salt) catalyzed by the accordant UP and PNP in Tris∙HCl buffer gave 2SUd and 2’-deoxy-5-azacytidine in 27% and 15% yields, respectively. 6-Azauracil and 6-azathymine showed good substrate properties for both TP and UP, whereas only TP recognizes 2-thio-6-azathymine as a substrate. 5-Phenyl and 5-tert-butyl derivatives of 6-azauracil and its 2-thioxo derivative were tested as substrates for UP and TP, and only 5-phenyl- and 5-tert-butyl-6-azauracils displayed very low substrate activity. The role of structural peculiarities and electronic properties in the substrate recognition by E. coli nucleoside phosphorylases is discussed.

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Temperature, Mitochondria, and Reye's Syndrome

PEDIATRICS ◽

10.1542/peds.71.6.985a ◽

1983 ◽

Vol 71 (6) ◽

pp. 985-986

Author(s):

R. DON BROWN ◽

JOHN T. WILSON

Keyword(s):

Mitochondrial Damage ◽

Reye's Syndrome ◽

Enhancing Effect ◽

Control Subjects ◽

Epidemiologic Data ◽

Higher Temperature ◽

And Control

In Reply.— El-Mallakh raises hypothetical questions about an enhancing effect of fever on mitochondrial damage associated with Reye's syndrome. Our article on aspirin and Reye's syndrome1 emphasized the role of prodromal illness in use of aspirin. Fever was only one of several [See table in the PDF] prodormal illness events that were different in patients as compared with control subjects. Results of our analysis of the epidemiologic data from the Ohio study reveal a statistically significant higher temperature in those children which Reye's syndrome as compared with unmatched control subjects (Table) as well as in patients and control subjects matched for record temperatures.1

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The role of frost cracking in local denudation of steep Alpine rockwalls over millennia (Eiger, Switzerland)

Earth Surface Dynamics ◽

10.5194/esurf-8-637-2020 ◽

2020 ◽

Vol 8 (3) ◽

pp. 637-659

Author(s):

David Mair ◽

Alessandro Lechmann ◽

Romain Delunel ◽

Serdar Yeşilyurt ◽

Dmitry Tikhomirov ◽

...

Keyword(s):

Swiss Alps ◽

Rock Fall ◽

Temperature Changes ◽

Rock Face ◽

Temperature Conditions ◽

Denudation Rates ◽

Reconstructed Temperature ◽

Cryogenic Processes

Abstract. Denudation of steep rockwalls is driven by rock fall processes of various sizes and magnitudes. Rockwalls are sensitive to temperature changes mainly because thermo-cryogenic processes weaken bedrock through fracturing, which can precondition the occurrence of rock fall. However, it is still unclear how the fracturing of rock together with cryogenic processes impacts the denudation processes operating on steep rockwalls. In this study, we link data on long-term rockwall denudation rates at the Eiger (Central Swiss Alps) with the local bedrock fabric and the reconstructed temperature conditions at these sites, which depend on the insolation pattern. We then estimate the probability of bedrock for failure through the employment of a theoretical frost cracking model. The results show that the denudation rates are low in the upper part of the NW rockwall, but they are high both in the lower part of the NW rockwall and on the SE face, despite similar bedrock fabric conditions. The frost cracking model predicts a large difference in cracking intensity from ice segregation where the inferred efficiency is low in the upper part of the NW rockwall but relatively large on the lower section of the NW wall and on the SE rock face of the Eiger. We explain this pattern by the differences in insolation and temperature conditions at these sites. Throughout the last millennium, temperatures in bedrock have been very similar to the present. These data thus suggest the occurrence of large contrasts in microclimate between the NW and SE walls of the Eiger, conditioned by differences in insolation. We use these contrasts to explain the relatively low denudation rates in the upper part of the NW rockwall and the rapid denudation in the SW face and in the lower part of the NW rock face where frost cracking is more efficient.

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Self-Assembly of Alkali Lignin in Tetrahydrofuran

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.550-553.57 ◽

2012 ◽

Vol 550-553 ◽

pp. 57-61

Author(s):

Hao Li ◽

Yong Hong Deng ◽

Kai Huang

Keyword(s):

Charge Transfer ◽

Electrostatic Interaction ◽

Self Assembly ◽

The Self ◽

Charge Transfer Complexes ◽

Layer By Layer ◽

Alkali Lignin ◽

Higher Temperature ◽

Effects Of Temperature

Alkali lignin (AL) was used as a polyanion to form layer-by-layer self-assembled film with PDAC as a polycation. The effects of temperature and concentration on the adsorption characteristics of AL were investigated. Iodine was added into AL solutions to study the role of π-π interaction in self-assembly of AL and PDAC. Results show that the self-assembly of AL/PDAC is mainly driven by π-π interaction and electrostatic interaction. A higher temperature or a larger concentration can enhance the aggregation of lignin. I2 can form lignin–iodine charge–transfer complexes with AL to reduce the degree of aggregation of AL, so the adsorbed amount of AL decreases significantly with increasing iodine contents.

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Peroxovanadates and Its Bio-Mimicking Relation with Vanadium Haloperoxidases

Emerging Research on Bioinspired Materials Engineering - Advances in Chemical and Materials Engineering ◽

10.4018/978-1-4666-9811-6.ch007 ◽

2016 ◽

pp. 197-219

Author(s):

Pranjal Saikia ◽

Saitanya Kumar Bharadwaj ◽

Abu Taleb Miah

Keyword(s):

Amino Acids ◽

Active Site ◽

High Efficiency ◽

Recombinant Enzymes ◽

Vanadium Compounds ◽

Reaction Conditions ◽

The Cost ◽

Major Emphasis ◽

Protein Active Site

Vanadium Haloperoxidases (VHPOs) have been used in a variety of biotransformations showing remarkable stereoselectivity and regiospecificity. The high efficiency of the enzyme is influenced by the protein active site and the role of certain amino acids in activation of vanadium(V)-bound peroxide for halide oxidation. The use of natural or recombinant enzymes, or biomimetic vanadium compounds brings up issues regarding the cost of production and reaction conditions. In this chapter, the primary intent is to provide a simple and clear picture of functional mimicking nature of peroxovanadium compounds with haloperoxidases enzymes to the readers. Major emphasis would be given to examine the reactivity of the vanadium haloperoxidases with mechanism.

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The Role of Saccharomyces cerevisiae Yeast and Lactic Acid Bacteria in the Formation of 2-Propanol from Acetone during Fermentation of Rye Mashes Obtained Using Thermal-Pressure Method of Starch Liberation

Molecules ◽

10.3390/molecules24030610 ◽

2019 ◽

Vol 24 (3) ◽

pp. 610 ◽

Cited By ~ 5

Author(s):

Katarzyna Pielech-Przybylska ◽

Maria Balcerek ◽

Urszula Dziekońska-Kubczak ◽

Barbara Pacholczyk-Sienicka ◽

Grzegorz Ciepielowski ◽

...

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Thermal Pressure ◽

Yellowness Index ◽

Pressure Method ◽

Fermentation Temperature ◽

L Value ◽

Higher Temperature ◽

Positive Correlations

This study set out to assess the acetone content in rye sweet mashes prepared using the thermal-pressure method of starch liberation, and to investigate the formation of 2-propanol during the fermentation process. In the first set of experiments, we evaluated the correlation between the color and the content of acetone and furfural in industrially produced sweet mashes (n = 37). The L * value was negatively correlated with the content of both acetone and furfural, while chromatic parameters a * and b * and the yellowness index (YI) had strong positive correlations with acetone (r > 0.9) and furfural (r > 0.8 for a * and r > 0.9 for b * and YI). In the second set of experiments, we assessed the concentration of acetone and 2-propanol in distillery rye mashes, fermented by S. cerevisiae yeast and lactic acid bacteria. The influence of fermentation temperature on the formation of 2-propanol was also evaluated. The presence of 2-propanol in the post-fermentation media was confirmed, while a decrease in acetone content was observed. Fermentation temperature (27 °C or 35 °C) was found to have a significant effect on the concentration of 2-propanol in trials inoculated with lactic bacteria. The content of 2-propanol was more than 11 times higher in trials fermented at the higher temperature. In the case of yeast-fermented mashes, the temperature did not affect 2-propanol content. The acetone in the sweet mash was assumed to be a precursor of 2-propanol, which was found in the fermented mashes.

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