Exchange reactions in hot atom chemistry. I. Gaseous methyl iodide

1976 ◽  
Vol 29 (3) ◽  
pp. 485
Author(s):  
FCR Cattell
Keyword(s):  
Exchange Reaction ◽  
Methyl Iodide ◽  
Significant Contribution ◽  
Radioactive Iodine ◽  
Time Dependent ◽  
Exchange Reactions ◽  
Gaseous Mixtures ◽  
Heterogeneous Exchange ◽  
Atom Chemistry

High organic retentions of iodine-128 following the 127I(n,γ)128 I reaction in gaseous mixtures of methyl iodide and iodine result from a heterogeneous exchange reaction. The time-dependent organic retention can be related quantitatively to the 'age' of the radioactive iodine atoms. There is no evidence for a significant contribution from hot atom reactions, nor from the direct homogeneous exchange of iodine atoms with methyl iodide.

Exchange reactions in hot atom chemistry. II. Liquid methyl iodide

1976 ◽  
Vol 29 (3) ◽  
pp. 495
Author(s):  
FCR Cattell
Keyword(s):  
Methyl Iodide ◽  
Isotope Exchange ◽  
Radioactive Iodine ◽  
Hot Spot ◽  
Iodine Concentration ◽  
Square Root ◽  
Exchange Reactions ◽  
Isotope Exchange Reaction ◽  
Organic Combination ◽  
Atom Chemistry

When dilute solutions of iodine in methyl iodide are irradiated with neutrons more than 56% of the radioactive iodine-128 appears in organic combination. This increase arises from an isotope exchange reaction with a rate independent of iodine concentration. When more concentratedsolutions are irradiated the organic radioactivity is reduced below 56% and the reduction depends on the square root of iodine concentration. Results are examined in terms of the kinetic theory of hot reactions and also a treatment for distinguishing between 'Rot' and 'hot spot diffusive'reactions.

Preparation of Functionalized Diorganomagnesium Reagents in Toluene via Bromine or Iodine/Magnesium-Exchange Reactions

Synthesis ◽  
2021 ◽  
Author(s):  
Alexandre Desaintjean ◽  
Fanny Danton ◽  
Paul Knochel
Keyword(s):  
Exchange Reaction ◽  
Nitro Group ◽  
General Formula ◽  
Functional Groups ◽  
Exchange Reactions ◽  
Acyl Chlorides ◽  
Aryl Iodides ◽  
Highly Sensitive ◽  
Wide Range ◽  
Magnesium Exchange

A wide range of polyfunctionalized di(hetero)aryl- and dialkenyl-magnesium reagents were prepared in toluene within 10 to 120 min between −78 °C and 25 °C via an I/Mg- or Br/Mg-exchange reaction using reagents of the general formula R2Mg (R = sBu, Mes). Highly sensitive functional groups, such as a triazene or a nitro group, were tolerated in these exchange reactions, enabling the synthesis of various functionalized (hetero)arenes and alkenes derivatives after quenching with several electrophiles including allyl bromides, acyl chlorides, aldehydes, ketones, and aryl iodides.

THEORETICAL STUDIES ON THE COUPLING INTERACTIONS AND SELF-EXCHANGE REACTION MECHANISMS IN THE COMPLEXES OF NO WITH ONH AND NOH

2008 ◽  
Vol 07 (03) ◽  
pp. 435-446 ◽  
Author(s):  
PING LI ◽  
XIAOYAN XIE ◽  
YUXIANG BU ◽  
WEIHUA WANG ◽  
NANA WANG ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Exchange Reaction ◽  
Reaction Mechanisms ◽  
Natural Bond Orbital ◽  
Theoretical Studies ◽  
Exchange Reactions ◽  
Electron Transfer Mechanism ◽  
Proton Coupled Electron Transfer ◽  
Planar Geometries ◽  
Transfer Mechanisms

The coupling interactions and self-exchange reaction mechanisms between NO and ONH (NOH) have been systematically investigated at the B3LYP/6-311++G** level of theory. All the equilibrium complexes are characterized by the intermolecular H-bonds and co-planar geometries. The cisoid NOH/ON species is the most stable one among all the complexes considered due to the formation of an N – N bond. Moreover, all the cisoid complexes are found to be more stable than the corresponding transoid ones. The origin of the blueshifts occurring in the selected complexes has been explored, employing the natural bond orbital (NBO) calculations. Additionally, the proton transfer mechanisms for the self-exchange reactions have been proposed, i.e. they can proceed via the three-center proton-coupled electron transfer or five-center cyclic proton-coupled electron transfer mechanism.

An all-in-one approach for synthesis and functionalization of nano colloidal gold with acetylacetone

2021 ◽  
Author(s):  
Li Zhang ◽  
Hongcen Zheng ◽  
Yonghai Gan ◽  
Bingdang Wu ◽  
Zhihao Chen ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Ligand Exchange ◽  
Fold Increase ◽  
Charge Transfer Complexes ◽  
Photochemical Property ◽  
Exchange Reactions ◽  
Ligand Exchange Reaction ◽  
Enhanced Photoluminescence ◽  
Good Imaging ◽  
Imaging Probes

Abstract Controllable synthesis, proper dispersion, and feasible functionalization are crucial requirements for the application of nanomaterials in many scenarios. Here, we report an all-in-one approach for the synthesis and functionalization of gold nanoparticles (AuNPs) with the simplest β-diketone, acetylacetone (AcAc). With this approach, the particle size of the resultant AuNPs was tunable by simply adjusting the light intensity or AcAc dosage. Moreover, owing to the capping role of AcAc, the resultant AuNPs could be stably dispersed in water for a year without obvious change in morphology and photochemical property. Formation of ligand to metal charge transfer complexes was found to play an important role in the redox conversion of Au with AcAc. Meanwhile, the moderate complexation ability enables the surface AcAc on the AuNPs to undergo ligand exchange reactions. With the aid of Ag+, the AuNPs underwent ligand exchange reaction with glutathione and exhibited enhanced photoluminescence (PL) with a maximum of 22-fold increase in PL intensity. The PL response was linear to the concentration of glutathione in the range of 0~500 μM. Such a ligand exchange reaction makes the obtained AuNPs being good imaging probes. To the best of our knowledge, this is the first work on illustrating the roles of AcAc as a multifunctional ligand in fabrication of NPs, which sheds new light on the surface modulation in synthesis of nanomaterials.

scholarly journals Regioselective Synthesis of 5-Propyl-2-((trityloxy)methyl)thiophene-3-carbaldehyde

Molbank ◽  
10.3390/m1289 ◽  
2021 ◽  
Vol 2021 (4) ◽  
pp. M1289
Author(s):  
Sukanta Bar
Keyword(s):  
Exchange Reaction ◽  
Regioselective Synthesis ◽  
Exchange Reactions ◽  
Halogen Exchange

5-propyl-2-((trityloxy)methyl)thiophene-3-carbaldehyde was synthesized by using the concept of chemo- and regioselective Br/Li exchange reaction from 3-bromo-5-propyl-2-((trityloxy)methyl)thiophene. This is a five-step protocol starting from thiophene with an overall yield of 33%. These lithium/halogen exchange reactions were carried out at −78 °C to rt over the period of 1 to 18 h depending on the reactivity of electrophiles.

Estimation of State of Cure with S-35

1960 ◽  
Vol 33 (1) ◽  
pp. 181-198
Author(s):  
H. L. Pederson
Keyword(s):  
Methyl Iodide ◽  
Benzene Solution ◽  
Active Material ◽  
Zinc Salt ◽  
Minor Importance ◽  
Exchange Reactions ◽  
Extensive Discussion ◽  
General Picture ◽  
Sulfur Bond

Abstract The use of S-35 in a vulcanizate can lead to an easy determination of bound sulfur as the ratio of activities of the acetone extracted sample and the same sample in its original state. At present, we do not specify the meaning of the sulfur value determined in this manner otherwise than that it is a gross value ideally free from accelerator sulfur. A number of Russian papers have reported the use of radiosulfur in vulcanization studies—for instance, Blokh's survey. Later Dogadkin described exchange reactions specifying the character of the sulfur bond in combination with an extensive discussion of the chain mechanism for the function especially of thiurams, leading to at least three types of vulcanizates: nonsulfur thiuram cures with —C—C— crosslinks and no exchange at all, DPG stocks having a high exchange rate, and thiazole mixes having intermediate rates. Of course, this is a very general picture explaining only the outstanding differences in aging stabilities imported in the systems mentioned. The quoted papers give very little experimental detail. However, there is a description of the exchange that can be performed by boiling the sample in a benzene solution of the reactant—e.g., sulfur or accelerator. It is of minor importance where the radioactivity is placed; however, the treatment of inactive vulcanizates with solutions of active material is very unpleasant. Therefore the active material is added in every case by compounding and the exchange is carried out by means of an inactive solution in acetone. The present work was undertaken to investigate differences in stability of the sulfur bond in vulcanizates having increasing states of cure, preferentially in a series of vulcanizations at constant temperature. In addition to exchange with elemental sulfur and sulfur donors (tetramethylthiuramdisulfide) we have investigated the Meyer and Hohemenser reaction with methyl iodide, more elaborately developed by the brilliant work of Selker and Kemp. This reaction is thought specifically to indicate the allylic bound sulfur. It is easily performed by boiling the active vulcanizate with a mixture of methyl iodide and acetone. Fletcher and Fogg indicate in their recent work that thiuram-sulfur systems owe their remarkable aging resistance to the content of ZnDC formed by the decomposition of thiuram during cure. Further, it is well known that certain compounds, such as the zinc salt of MBT, give a similar improvement. We therefore stress that stabilities as stated here, based upon the exchange reaction, will not necessarily bear a unique relation to aging stability, but rather show an intrinsic stability of the sulfur bond.

Recent Progress in σ-Bond Cross-Exchange Reactions to Access Diverse Silacycles

Synlett ◽  
2018 ◽  
Vol 29 (20) ◽  
pp. 2595-2600 ◽  
Author(s):  
Dongbing Zhao ◽  
Wen-Tao Zhao ◽  
Fang Gao
Keyword(s):  
Exchange Reaction ◽  
Recent Progress ◽  
Atom Economy ◽  
Exchange Reactions ◽  
Rapid Access ◽  
Recent Advances

The σ-bond cross-exchange reaction, which involves cleavage and subsequent exchange between different nonpolar σ-bonds, constitutes an attractive protocol for rapid access to organic skeletons with 100% atom economy. Herein, we give a brief summary of recent achievements in this approach for the synthesis of diverse silacycles, highlighting our recent advances in the first intermolecular σ-bond exchange between C–C bonds of cyclopropenones and C–Si bonds of (benzo)silacyclobutanes.1 Introduction2 σ-Bond Exchange-Reaction of Benzocyclobutanones to Silacycles3 σ-Bond Exchange-Reaction of Ethyl Cyclopropylideneacetates to Silacycles4 σ-Bond Exchange-Reaction of Cyclopropenones to Silacycles5 Conclusion

Preparation of (1R )[1—2H]- and (1S)[1—2H]-Alcohols by Exchange Reactions Catalyzed by Yeast or a Coupled Enzyme System

1973 ◽  
Vol 28 (5-6) ◽  
pp. 241-246 ◽  
Author(s):  
Helmut Günther ◽  
Miguel A. Alizade ◽  
Max Kellner ◽  
Florian Biller ◽  
Helmut Simon
Keyword(s):  
Alcohol Dehydrogenase ◽  
Exchange Reaction ◽  
Enzyme System ◽  
Deuterium Oxide ◽  
Exchange Reactions ◽  
Ordinary Water

All possible enantiomers of stereospecifically labelled [1-2H] ethanol, propanol and butanol have been prepared on a scale of up to 7 ml. The R forms have been obtained by incubation of the alcohols with alcohol dehydrogenase and diaphorase (NAD: Lipoamide oxidoreductase, EC 1.6.4.3) in presence of catalytic amounts of NAD+/NADH in deuterium oxide. The S forms have been prepared with the same enzymes in ordinary water, from the corresponding [1,1-2H] alcohols. (IS) [1-2H] ethanol was prepared from [1,1-2H] ethanol and ordinary water, by a yeast catalyzed exchange reaction.

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