scholarly journals SYNTHETIC POTENTIAL OF 9,10-ANTHRAQUINONYLDIAZONIUM SALTS

2020 ◽  
Vol 86 (9) ◽  
pp. 55-72
Author(s):  
Maryna Stasevich ◽  
Viktor Zvarych ◽  
Volodymyr Novikov ◽  
Mykhailo Vovk
Keyword(s):  
Diazonium Salts ◽  
Chemical Transformations ◽  
Reaction Products ◽  
Heterocyclic Derivatives ◽  
First Time ◽  
Synthetic Transformations

For the first time, the literature sources concerning the chemical transformations of diazonium salts of 1(2)-amino-9,10-anthracenediones are generalized and systematized. The potential of 9,10-dioxoanthracenyldiazonium salts as key substrates in the preparation of various linear-functionalized, acyclic and heterocyclic derivatives has been determined. The main synthetic transformations of diazonium salts of amino-9,10-anthracenediones, which are  realized without preserving the azo function lead to the formation of reaction products of Sandmeyer, Meerwein, and Gomberg–Bachmann–Hay, are analyzed. The use of 9,10-dioxoanthracenyldiazonium salts or products of their transformations for obtaining heteryl-containing condensed and functionalized derivatives is presented.

scholarly journals New Approach to Synthesis of Tetralin via Naphthalene Hydrogenation in Supercritical Conditions Using Polymer-Stabilized Pt Nanoparticles

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1362
Author(s):  
Alexey V. Bykov ◽  
Daria V. Alekseeva ◽  
Galina N. Demidenko ◽  
Alexandre L. Vasiliev ◽  
Linda Nikoshvili ◽  
...  
Keyword(s):  
Batch Reactor ◽  
Process Intensification ◽  
Pt Nanoparticles ◽  
Chemical Transformations ◽  
Reaction Products ◽  
Large Step ◽  
Lower Viscosity ◽  
Green Chemical Synthesis ◽  
Downstream Processes ◽  
First Time

Supercritical (SC) fluid technologies are well-established methods in modern green chemical synthesis. Using SC fluids as solvents instead of traditional liquids gives benefits of higher diffusivity and lower viscosity, which allows mass transfer intensification and, thus, an increased production rate of chemical transformations. Therefore, a conjugation of heterogeneous catalysis with SC media is a large step toward a green chemistry. Tetralin (TL) is an important hydrogen donor solvent used for biomass liquefaction. In industry, TL is obtained via catalytic hydrogenation of naphthalene (NL). Herein, for the first time we have demonstrated the NL hydrogenation with close to 100% selectivity to TL at almost full conversion in the SC hexane. The observed transformation rates in SC hexane were much higher allowing process intensification. The downstream processes can be also facilitated since hexane after depressurisation can be easily separated from the reaction products via simple rectification. The TL synthesis was studied in a batch reactor at variation of reaction temperature and overall pressure. For the first time for this process, low Pt-loaded (1 wt.%) nanoparticles stabilized within hyper-cross-linked aromatic polymer (HAP) were applied. The Pt/HAP catalyst was stable under reaction conditions (250 °C, 6 MPa) allowing its recovery and reuse.

scholarly journals Thermodynamic simulation of oxidation process of the Moss-Mo3Si hypoeutectic alloy, doped with scandium or neodymium

2019 ◽  
Vol 57 (2) ◽  
pp. 90-100
Author(s):  
Alexey V. Larionov ◽  
◽  
Ludmila Y. Udoeva ◽  
Vladimir M. Chumarev ◽  
◽  
...  
Keyword(s):  
Oxidation Process ◽  
Thermodynamic Simulation ◽  
Oxidation Products ◽  
Hypoeutectic Alloy ◽  
Protective Film ◽  
Chemical Transformations ◽  
Reaction Products ◽  
Moist Air ◽  
Condensed Product ◽  
Hsc Chemistry

In order to study the effect of yttrium additives on the oxidation of molybdenum silicide alloys, thermodynamic modeling of the interaction in Mo-Mo3Si-Sc5Si3 и Mo-Mo3Si-NdSi systems with dry and moist air was performed in the temperature range 25-2000 °C. The calculations were performed using the HSC Chemistry 6.12 software, into the database of which the calculated missing thermochemical characteristics silicates, molybdates of scandium and neodymium were entered. Based on the obtained dependences of the composition of phases on temperature and charge of the oxidant (air or vapor-air mixture), the sequence of phase formation was determined and the compositions of oxidation products were estimated. It is shown that, under equilibrium conditions, the oxidation process with dry and moist air proceeds almost equally, since the interaction of the components of the alloy with oxygen is thermodynamically preferable than with water vapor. According to the obtained thermodynamic models, the oxidation process of the Mo-5Si-3(Sc, Nd) (wt.%) alloys involves a sequence of the following chemical transformations: at the beginning Mo and Sc (Nd) silicides oxidize forming Sc2O3 ( Nd2O3), SiO2 and elemental Mo, then molybdenum is oxidized to MoO2 and Sc2O3 or Nd2O3 interacts with SiO2 with the formation of appropriate silicates Sc2Si2O7 или Nd2Si2O7. As a result of the complete oxidation of the alloy, MoO3 and Sc2(MoO4)3 or Nd2Mo4O15 are added to the condensed product, and molybdenum oxide (MoO3)n vapor appears in the gas phase. In addition, the formation of Nd2Mo2O7 and Nd2 (MoO4)3 is possible. During the oxidation of the Mo-5Si-3Nd alloy at T> 1700 oC, Nd(OH)3 can be formed in the condensed reaction products. According to the results of complete thermodynamic analysis, the formation of silicates and molybdates of scandium and neodymium can promote to the formation of a protective film on the surface of the alloys, which limits the diffusion of oxygen in them, and as a result, the oxidation resistance of alloys should increase.

Black phosphorus as a metal-free, visible-light-active heterogeneous photoredox catalyst for the direct C–H arylation of heteroarenes

2020 ◽  
Vol 56 (44) ◽  
pp. 5901-5904 ◽  
Author(s):  
Erbay Kalay ◽  
Hüseyin Küçükkeçeci ◽  
Haydar Kilic ◽  
Önder Metin
Keyword(s):  
Visible Light ◽  
Black Phosphorus ◽  
Diazonium Salts ◽  
Metal Free ◽  
Visible Light Active ◽  
First Time

We report for the first time the employment of black phosphorus (BP) as a metal free, visible-light-active and reusable heterogeneous photoredox catalyst for the direct C–H arylation of heteroarenes (furan and thiophene) with aryl diazonium salts.

Induction and Transcription Studies of the Dextransucrase Gene in Leuconostoc mesenteroides NRRL B-512F

1999 ◽  
Vol 65 (12) ◽  
pp. 5504-5509 ◽  
Author(s):  
M. Quirasco ◽  
A. López-Munguía ◽  
M. Remaud-Simeon ◽  
P. Monsan ◽  
A. Farrés
Keyword(s):  
High Performance ◽  
Leuconostoc Mesenteroides ◽  
Carbon Sources ◽  
Promoter Sequence ◽  
Culture Conditions ◽  
Start Codon ◽  
Reaction Products ◽  
Product Specificity ◽  
First Time

ABSTRACT Dextransucrase production by Leuconostoc mesenteroidesNRRL B-512F in media containing carbon sources other than sucrose is reported for the first time. Dextransucrases were analyzed by gel electrophoresis and by an in situ activity assay. Their polymers and acceptor reaction products were also compared by 13C nuclear magnetic resonance and high-performance liquid chromatography techniques, respectively. From these analyses, it was found that, independently of the carbon source, L. mesenteroides NRRL B-512F produced dextransucrases of the same size and product specificity. The 5′ ends of dextransucrase mRNAs isolated from cells grown under different culture conditions were identical. Based on this evidence, we conclude that dextransucrases obtained from cells grown on the various carbon sources result from the transcription of the same gene. The control of expression occurs at this level. The low dextransucrase yields from cultures in d-glucose ord-fructose and the enhancement of dextransucrase gene transcription in the presence of sucrose suggest that an activating phenomenon may be involved in the expression mechanism. Dextransucrase mRNA has a size of approximately 4.8 kb, indicating that the gene is located in a monocistronic operon. The transcription start point was localized 34 bp upstream from the ATG start codon. The −10 and −35 sequences found, TATAAT and TTTACA, were highly homologous to the only glycosyltransferase promoter sequence reported for lactic acid bacteria.

scholarly journals The Formation of Glycerol Oligomers with Two New Types of End Groups in the Presence of a Homogeneous Alkaline Catalyst

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 144 ◽  
Author(s):  
Dawid Kansy ◽  
Kornelia Bosowska ◽  
Krystyna Czaja ◽  
Anna Poliwoda
Keyword(s):  
Catalyst Concentration ◽  
Reaction Medium ◽  
Hydroxyl Groups ◽  
Ionization Mass ◽  
Carboxylate Group ◽  
Reaction Products ◽  
Direct Infusion ◽  
Alkaline Catalyst ◽  
End Groups ◽  
First Time

The purpose of this work was to synthesize and characterize oligoglycerols with the chains of more than four repeating units. Those oligoglycerols may have some interesting applications, among others, as polyoxyalkylation starters. The glycerol oligomerization process was carried out during 12 h, at 230 °C, under the pressure of 0.4 bar, with the use of sodium carbonate as a homogeneous basic catalyst; various concentrations of the catalyst in the reaction medium were used. The reaction products were analyzed with the use of direct infusion electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance (13C NMR) and Fourier transform infrared spectroscopy (FTIR) techniques. Based on the analytical findings, the compositions of the obtained product mixtures and the structures of oligoglycerols present in individual fractions were determined. The effect of catalyst concentration on the composition of the post-reaction mixture was observed. Moreover, in addition to the conventional linear oligomers (α,α-oligoglycerols), two new types of the oligomers were for the first time detected in the post-reaction mixture: one with two hydroxyl groups and the other with a carboxylate group at the α-carbon atom.

scholarly journals A Simple and Efficient Method for the Partial Synthesis of Pure (3R,3’S)-Astaxanthin from (3R,3’R,6’R)-Lutein and Lutein Esters via (3R,3’S)-Zeaxanthin and Theoretical Study of Their Formation Mechanisms

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1386 ◽  
Author(s):  
Eloy Rodríguez-deLeón ◽  
J. Jiménez-Halla ◽  
José Báez ◽  
M. Bah
Keyword(s):  
Health Risks ◽  
Density Functional ◽  
Human Consumption ◽  
Formation Mechanisms ◽  
Chemical Transformations ◽  
Partial Synthesis ◽  
One Pot ◽  
Commercial Source ◽  
The One ◽  
First Time

Carotenoids are natural compounds that have important roles in promoting and maintaining human health. Synthetic astaxanthin is a highly requested product by the aquaculture industry, but natural astaxanthin is not. Various strategies have been developed to synthesize this carotenoid. Nonetheless, these approaches have not only provided limited global yields, but its main commercial source also carries several health risks for humans. In this contribution, the one-pot base-catalyzed reaction of (3R,3’R,6’R)-lutein (1) esters has resulted in a successful isomerization process to easily obtain up to 95% meso-zeaxanthin (2), which in turn is oxidized to (3R,3’S)-astaxanthin (3) with a global yield of 68%. The same oxidation performed with UV irradiation (365 nm) for 5 min provided the highest global yield (76%). These chemical transformations have also been achieved with a significant reduction of the health risks associated with its potential human consumption. Furthermore, this is the first time only one of the configurational isomers has been obtained semisynthetically. The poorly understood formation mechanisms of these two compounds were also investigated using Density-Functional Theory (DFT) calculations. These theoretical studies revealed that the isomerization involves a base-catalyzed deprotonation at C-6’, followed by C-4’ protonation, while the oxidation occurs via free radical mechanisms.

scholarly journals Repair of DNA Alkylation Damage by theEscherichia coliAdaptive Response Protein AlkB as Studied by ESI-TOF Mass Spectrometry

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Deyu Li ◽  
James C. Delaney ◽  
Charlotte M. Page ◽  
Alvin S. Chen ◽  
Cintyu Wong ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Chemical Oxidation ◽  
Dna Alkylation ◽  
Reaction Products ◽  
Ionization Time ◽  
Alkylation Damage ◽  
Living Organisms ◽  
First Time ◽  
Dependent Mechanism

DNA alkylation can cause mutations, epigenetic changes, and even cell death. All living organisms have evolved enzymatic and non-enzymatic strategies for repairing such alkylation damage. AlkB, one of theEscherichia coliadaptive response proteins, uses an α-ketoglutarate/Fe(II)-dependent mechanism that, by chemical oxidation, removes a variety of alkyl lesions from DNA, thus affording protection of the genome against alkylation. In an effort to understand the range of acceptable substrates for AlkB, the enzyme was incubated with chemically synthesized oligonucleotides containing alkyl lesions, and the reaction products were analyzed by electrospray ionization time-of-flight (ESI-TOF) mass spectrometry. Consistent with the literature, but studied comparatively here for the first time, it was found that 1-methyladenine, 1,N6-ethenoadenine, 3-methylcytosine, and 3-ethylcytosine were completely transformed by AlkB, while 1-methylguanine and 3-methylthymine were partially repaired. The repair intermediates (epoxide and possibly glycol) of 3,N4-ethenocytosine are reported for the first time. It is also demonstrated thatO6-methylguanine and 5-methylcytosine are refractory to AlkB, lending support to the hypothesis that AlkB repairs only alkyl lesions attached to the nitrogen atoms of the nucleobase. ESI-TOF mass spectrometry is shown to be a sensitive and efficient tool for probing the comparative substrate specificities of DNA repair proteinsin vitro.

Colorimetric Determination of Certain Phenol Derivatives in Pharmaceutical Preparations

1981 ◽  
Vol 64 (6) ◽  
pp. 1442-1445
Author(s):  
Sayed M Hassan ◽  
Mohammed I Walash ◽  
Sanaa M El-Sayed ◽  
Abdel Malek Abou Ouf
Keyword(s):  
Pharmaceutical Preparations ◽  
Sulfanilic Acid ◽  
Diazonium Salts ◽  
Colorimetric Determination ◽  
Reaction Products ◽  
Optimum Conditions ◽  
Phenol Derivatives ◽  
The Mean ◽  
Colorimetric Methods

Abstract Simple colorimetric methods are reported for determining both acetaminophen and oxyphenbutazone. These methods are based on coupling between the phenolic compound and the diazonium salts of both sulfanilic acid and p-nitroaniline; the optimum conditions for the reactions were carefully studied. For acetaminophen, the reaction products with diazosulfanilic acid and diazo-p-nitroaniline show maximum absorbance at 480 and 425 nm, respectively. The mean percentage recoveries for authentic samples were 99.5 ± 1.1 and 100.6 ± 0.66, respectively (P = 0.05). For oxyphenbutazone, the obtained colors showed maxima at 385 nm with diazosulfanilic acid and 490 nm with diazo-p-nitroaniline reactions. The mean percentage recoveries for authentic samples were 99.8 ± 0.27 and 100.1 ± 0.57, respectively (P = 0.05). The proposed methods were successfully applied to the analysis of commercial preparations; results were statistically compared with those of other methods.

Scanning Tunneling Microscopy Studies of the Initial Stages of Thin Film Growth: the Role of the Surface Dangling Bonds

1987 ◽  
Vol 105 ◽  
Author(s):  
Ph. Avouris ◽  
R. Wolkow ◽  
F. Bozso ◽  
R. J. Hamers
Keyword(s):  
Film Growth ◽  
Thin Film Growth ◽  
Scanning Tunneling ◽  
Reaction Products ◽  
Dangling Bonds ◽  
Surface Chemical Reaction ◽  
Tunneling Microscopy ◽  
Reacting Systems ◽  
First Time

AbstractWe present STM and photoemission studies of the reactions of Si(100)-(2×1) and Si(111)–(7×7) with NH3. STM allows us to image the occupied and unoccupied states of the reacting systems and to obtain electronic spectra with atomic lateral resolution. Thus, for the first time, a surface chemical reaction can be probed at the atomic level. We find that both surfaces are reactive even at 100K. However, both the extent of the reaction and the reaction products at 300K are different on the two surfaces. STM also shows that while surface dangling bonds are essential for low-temperature reactivity, not all triplycoordinated Si sites are chemically equivalent. On the 7×7 surface the rest-atoms are more reactive than center-adatoms which, in turn, are more reactive than corner-adatoms.

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