Gold-catalyzed dual C–C bond cleavage of biphenylenes bearing a pendant alkyne at ambient temperature

2020 ◽  
Vol 18 (30) ◽  
pp. 5826-5831 ◽  
Author(s):  
Hideaki Takano ◽  
Sari Okazaki ◽  
Shun Nishibe ◽  
Takeharu Ito ◽  
Natsumi Shiozawa ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Room Temperature ◽  
Bond Cleavage ◽  
Gold Catalyst ◽  
Skeletal Rearrangement ◽  
Cationic Gold

We report a catalytic skeletal rearrangement of biphenylenes with a pendant alkyne moiety at room temperature by a cationic gold catalyst, which involves the cleavage of two bonds: the C–C bond of biphenylene and the C(sp)–C(sp2 or sp3) bond.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

Room Temperature Alkali Metal Reduction of Carbon Dioxide

2020 ◽  
Author(s):  
Lucas A. Freeman ◽  
Akachukwu D. Obi ◽  
Haleigh R. Machost ◽  
Andrew Molino ◽  
Asa W. Nichols ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Room Temperature ◽  
Chemical Reduction ◽  
Bond Cleavage ◽  
Open Shell ◽  
Metal Reduction ◽  
One Pot ◽  
Earth Abundant ◽  
Electron Reduction

The reduction of the relatively inert carbon–oxygen bonds of CO<sub>2</sub> to access useful CO<sub>2</sub>-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO<sub>2</sub> and the MGE. Herein we report the first successful chemical reduction of CO<sub>2</sub> at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO<sub>2</sub> adduct (<b>1</b>) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO<sub>2</sub>)]<sub>n</sub>(M = Li, Na, K, <b> 2</b>-<b>4</b>) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M<sub>2</sub>(CAAC–CO<sub>2</sub>)]<sub>n </sub>(<b>5</b>-<b>8</b>). It is notable that these crystalline clusters of reduced CO<sub>2</sub> may also be isolated via the “one-pot” reaction of free CO<sub>2</sub> with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products <b>2</b>-<b>8</b> were investigated using a combination of experimental and theoretical methods.<br>

Synthesis of 2,3-dihydroquinazolinones and quinazolin-4(3H)-ones catalyzed by graphene oxide nanosheets in an aqueous medium: “on-water” synthesis accompanied by carbocatalysis and selective C–C bond cleavage

RSC Advances ◽  
2016 ◽  
Vol 6 (27) ◽  
pp. 22320-22330 ◽  
Author(s):  
Nazia Kausar ◽  
Indranil Roy ◽  
Dipankar Chattopadhyay ◽  
Asish R. Das
Keyword(s):  
Graphene Oxide ◽  
Aqueous Medium ◽  
Room Temperature ◽  
Bond Cleavage ◽  
Graphene Oxide Nanosheets ◽  
Graphene Oxide Nanosheet

Graphene oxide nanosheet catalyzed strategies for construction of 2,3-dihydroquinazolinones and quinazolin-4(3H)-ones starting from anthranilamide and an aldehyde/ketone in aqueous medium at room temperature have been realized.

Photocatalytic Chemoselective C–C Bond Cleavage at Room Temperature in Dye-Sensitized Photoelectrochemical Cells

ACS Catalysis ◽  
2021 ◽  
pp. 3771-3781
Author(s):  
Shuya Li ◽  
Saerona Kim ◽  
Andrew H. Davis ◽  
Jingshun Zhuang ◽  
Eric Wolfgang Shuler ◽  
...  
Keyword(s):  
Room Temperature ◽  
Bond Cleavage ◽  
Photoelectrochemical Cells ◽  
Dye Sensitized

Change in the Properties of a Lead-acid Battery Depending on the Cycling Speed and the Ambient Temperature

2021 ◽  
Vol 105 (1) ◽  
pp. 119-134
Author(s):  
Jana Zimáková ◽  
Petr Baca ◽  
Martin Langer ◽  
Tomáš Binar
Keyword(s):  
Ambient Temperature ◽  
High Temperatures ◽  
Room Temperature ◽  
Lead Acid Battery ◽  
Ambient Temperatures ◽  
Lead Acid Batteries ◽  
Temperature Dependences ◽  
Cycling Speed ◽  
Lead Acid

This work deals with lead-acid batteries, their properties and individual types that are available on the market. The temperature dependences of the battery parameters at different ambient temperatures and at different discharging and charging modes are measured. 6 batteries are tested at different charging currents, which provides information about their behavior both during discharge and at the time of charging. During the experiments, testing is not only performed at room temperature, but the batteries are also exposed to high temperatures up to 75 °C.

scholarly journals EFFECT OF MATURITY STAGES ON QUALITY AND SHELF LIFE OF “SOLO” PAPAYA FRUITS DURING STORAGE

2019 ◽  
pp. 57-68
Keyword(s):  
Ambient Temperature ◽  
Shelf Life ◽  
Cold Storage ◽  
Room Temperature ◽  
Colour Change ◽  
Soluble Solids ◽  
Maturity Stages ◽  
Solids Content ◽  
Sensorial Evaluation ◽  
Stage 1

“Solo” papaya fruits were harvested in October, 2016 & 2017 seasons from a commercial orchard located in Ismailia Governorate, Egypt. Papaya fruits were harvested at three maturity stages: 25% yellow (stage 1), 50% yellow (stage 2) and 100% yellow (stage 3) and evaluated during storage at ambient temperature (20°C ± 2) for 4 days + at 80- 85% RH or during cold storage at 6°C + 90- 95% RH for 20 days. Papaya fruits softened very rapidly at room temperature after harvest and had 4 days shelf life. However, the fruit can be stored for 20 days at 6°C with little changes in firmness and the fruit apparently progressed in normal ripening upon removal to ambient temperature (20°C) for 3 days. All colour values (a*, L* and C*) were linearly increased during cold storage. Conversely, as a result of colour change from green to orange-red, h° values decreased. Soluble solids content was not affected during ripening at 20°C and remained steady. Fruit harvested at stage 2 and stored at 6°C for 20 days following 3 days at 20°C had superior score for sensorial evaluation.

An efficient multicomponent, one-pot synthesis of Betti bases catalyzed by cerium (IV) ammonium nitrate (CAN) at ambient temperature

2016 ◽  
Vol 5 (4) ◽  
Author(s):  
Ramadan Ahmed Mekheimer ◽  
Abdullah Mohamed Asiri ◽  
Afaf Mohamed Abdel Hameed ◽  
Reham R. Awed ◽  
Kamal Usef Sadek
Keyword(s):  
Ambient Temperature ◽  
Environmental Pollution ◽  
Ammonium Nitrate ◽  
Room Temperature ◽  
Catalytic Amount ◽  
High Yield ◽  
Reaction Conditions ◽  
One Pot ◽  
Work Up ◽  
Cerium Iv Ammonium Nitrate

AbstractStarting from readily available 2-naphthol, aldehydes, aryl and alkylamines, a variety of Betti bases were efficiently synthesized utilizing a catalytic amount of cerium (IV) ammonium nitrate (CAN) at room temperature. This protocol has advantages of high yield, mild reaction conditions, no environmental pollution, diversity of reactants and simple work up procedure.

Room Temperature, Metal-Free, Regio-Selective Arylselenation of Anilines Using Diselenides as Selenium Source

Synthesis ◽  
2022 ◽  
Author(s):  
Rekha Bai ◽  
Kamlesh Kumar Dabaria ◽  
Satpal Singh Badsara
Keyword(s):  
Ambient Temperature ◽  
Room Temperature ◽  
Bond Formation ◽  
Metal Free ◽  
Aniline Derivatives

A metal-free direct C-H selenation of aniline derivatives via an iodine catalysed C-Se bond formation using diselenides as a selenium source at ambient temperature is described. A variety of aniline derivatives underwent regio-selective C-H selenation with different diselenides to afford the corresponding aryl selenoethers in good to excellent yields.

The Chemical Evolution of a Nitrogenase Model, 20 Alkyl Molybdates(VI) and the Mechanism of Hydrocarbon Production by Nitrogenase [1]

1982 ◽  
Vol 37 (3) ◽  
pp. 380-385 ◽  
Author(s):  
G. N. Schrauzer ◽  
Laura A. Hughes ◽  
Norman Strampach
Keyword(s):  
Aqueous Solution ◽  
Alkaline Hydrolysis ◽  
Room Temperature ◽  
Bond Cleavage ◽  
Model Compounds ◽  
Hydrocarbon Production ◽  
Acidic Solutions ◽  
Reducing Conditions ◽  
Hydrolysis Of ◽  
Derivatives Of

Abstract Colorless alkylmolybdates(VI) of composition R-MoO3-are generated in aqueous solutions by the alkaline hydrolysis of complexes R-Mo(Bpy)(0)2Br(Bpy = 2,2′-bipyridyl, R = CH3 and higher alkyl). At room temperature in alkaline aqueous solution, the new organometallic derivatives of oxomolybdate(VI) are remarkably resistant against Mo-C bond hydrolysis. Decomposition occurs more rapidly on heating, affording unrearranged alkanes according to the eq.: R-MoO3- + OH-→RH + Mo04=. In acidic solutions, the methylmolybdate(VI) species decomposes with the formation of a mixture of methane and ethane while higher alkylmolybdates carrying hydrogen in the β-position relative to molybdenum undergo Mo-C bond heterolysis by way of β-elimina-tion: R-CH2CH2-MoO3 → Mo+4 (aq) + H+ + R-CH = CH2. The Mo-C bond of alkylmolybdates is resistant to oxidants but is very sensitive to cleavage under reducing conditions. Reductive Mo-C bond cleavage occurs particularly rapidly in the presence of thiols and reduced ferredoxin model compounds. The latter reactions simulate the terminal steps of hydrocarbon producing reactions of nitrogenase with alternate substrates such as CN-, R-CN or R-NC, confirming previous mechanistic conclusions concerning the mechanism of nitrogenase action.

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