Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Species reactive

Residence time and reactivity are strongly correlated through equation (7.2.9). This is true for seawater composition since Whitfield and Turner (1979) showed a rather good correlation between oceanic residence times and seawater-crustal rock partition coefficients which are taken as a measure of element reactivity in the ocean. Actually, a better estimate of reactivity is given by oceanic suspensions, so Li (1982) suggested to use pelagic clay-seawater concentration ratios as a proxy to partition coefficients. [Pg.349]

The mass balance equation (7.2.7) will now be solved for different cases (a) a finite amount of the species i is added to the reservoir at t = 0, (b) upstream concentration C-J is changed at t - 0, and (c) upstream concentration Cin is a periodic function of the time. [Pg.349]

The residence time rCd = rH/aCd and the limiting concentration CinCd/aCd are divided by a factor of 30 relative to a non-reactive case, e.g., chlorine. Entrainment by sediments flushes the excess Cd 30 times faster and decreases Cd steady-state concentration 30 times relative to a sediment-free lake. s= [Pg.351]

the constant terms must cancel out, hence [Pg.352]

The terms in cos(2nt/T) on both sides must be equal, hence [Pg.352]


The lubricant oxidation mechanism is free-radical in nature and the additives act on the kinetic oxidation chain by capturing the reactive species either by decomposition of the peroxides, or by deactivation of the metal. [Pg.358]

A reactive species in liquid solution is subject to pemianent random collisions with solvent molecules that lead to statistical fluctuations of position, momentum and internal energy of the solute. The situation can be described by a reaction coordinate X coupled to a huge number of solvent bath modes. If there is a reaction... [Pg.832]

A microwave pulse from a tunable oscillator is injected into the cavity by an anteima, and creates a coherent superposition of rotational states. In the absence of collisions, this superposition emits a free-mduction decay signal, which is detected with an anteima-coupled microwave mixer similar to those used in molecular astrophysics. The data are collected in the time domain and Fourier transfomied to yield the spectrum whose bandwidth is detemimed by the quality factor of the cavity. Hence, such instruments are called Fourier transfomi microwave (FTMW) spectrometers (or Flygare-Balle spectrometers, after the inventors). FTMW instruments are extraordinarily sensitive, and can be used to examine a wide range of stable molecules as well as highly transient or reactive species such as hydrogen-bonded or refractory clusters [29, 30]. [Pg.1244]

Luminescence has been used in conjunction with flow cells to detect electro-generated intennediates downstream of the electrode. The teclmique lends itself especially to the investigation of photoelectrochemical processes, since it can yield mfonnation about excited states of reactive species and their lifetimes. It has become an attractive detection method for various organic and inorganic compounds, and highly sensitive assays for several clinically important analytes such as oxalate, NADH, amino acids and various aliphatic and cyclic amines have been developed. It has also found use in microelectrode fundamental studies in low-dielectric-constant organic solvents. [Pg.1948]

The absorption of a light pulse instantaneously generates reactive species in high concentrations, either tlirough the fomiation of excited species or tlirough photodissociation of suitable precursors. The reaction can... [Pg.2125]

Figure C2.13.7. Change between polymerizing and etching conditions in a fluorocarbon plasma as detennined by tire fluorine-to-carbon ratio of chemically reactive species and tire bias voltage applied to tire substrate surface [36]. Figure C2.13.7. Change between polymerizing and etching conditions in a fluorocarbon plasma as detennined by tire fluorine-to-carbon ratio of chemically reactive species and tire bias voltage applied to tire substrate surface [36].
Figure C2.18.3. Relationship between ion-assisted etching and directionality in plasma etching, (a) Demonstration of the synergy between ion bombardment and reactive species during ion-assisted etching, (b) Ions incident on an etched feature. This situation prevails in glow discharges when the feature dimensions are much less than the plasma sheath thickness. Reproduced from [35]... Figure C2.18.3. Relationship between ion-assisted etching and directionality in plasma etching, (a) Demonstration of the synergy between ion bombardment and reactive species during ion-assisted etching, (b) Ions incident on an etched feature. This situation prevails in glow discharges when the feature dimensions are much less than the plasma sheath thickness. Reproduced from [35]...
The observation of nitration at a rate independent of the concentration and nature of the aromatic excludes AcONOa as the reactive species. The fact that zeroth-order rates in these solutions are so much faster than in solutions of nitric acid in inert organic solvents, and the fact that HNO3 and H2NO3+ are ineffective in nitration even when they are present in fairly lai e concentrations, excludes the operation of either of these species in solutions of acetyl nitrate in acetic anhydride. [Pg.103]

Charge diagrams suggest that the 2-amino-5-halothiazoles are less sensitive to nucleophilic attack on 5-position than their thiazole counterpart. Recent kinetic data on this reactivity however, show, that this expectation is not fulfilled (67) the ratio fc.. bron.c.-2-am.noih.azoie/ -biomoth.azoie O"" (reaction with sodium methoxide) emphasizes the very unusual amino activation to nucleophilic substitution. The reason of this activation could lie in the protomeric equilibrium, the reactive species being either under protomeric form 2 or 3 (General Introduction to Protomeric Thiazoles). The reactivity of halothiazoles should, however, be reinvestigated under the point of view of the mechanism (1690). [Pg.18]

Reactions of the 2-amino-4,5-substituted thiazole (52) in acetic acid with ethylene oxide has been reported to give the N-exocyclic disubstitution product (S3) (201) in a 40% yield (Scheme 38). The reactive species in this reaction is probably the carbocation generated in acetic acid by ethvlene oxide. [Pg.38]

All the examples of reactivity in acidic medium (Scheme 40) involve a reagent with a sp C hybridized electrophilic center, but the actual reactive species generated bears a sp C electrophilic center. In this case, exocyclic N-alkylation is not surprising (see Section III.2). [Pg.39]

Alkylation of 2-methylaminothiazole (204) with ROH in 85% sulfuric acid gives 2-methylimino-3-alkyl-4-thiazoIine (54). 2-Amino-4-rnethyl-thiazoie alkylated with an excess of isopropanol, however, gives 95% of 2-isopropylamino-4-methyl-5-isopropylthiazole (56). The same result is obtained with cyclohexanol (242). These results and those reported in Sections III.l.C and IV.l.E offer interesting new synthetic possibilities in thiazole chemistry. The reactive species in these alkylations is the conjugate acid of 2-aminothiazole. and the diversity of the products obtained suggests that three nucleophilic centers may be operative in this species. [Pg.47]

Here again the question of reactive species in the acidic medium remains open. It must be noted that bromination of 2-amino-5-methyl-pyridine (pK = 7) and 2-amino-5-nitropyridine (pJC = 2.8) in N sulfuric acid takes place on the free base (443). [Pg.79]

Carbocations derived from the alcohol are probably the reactive species, but data concerning by-products expected with carbocationic intermediates are lacking. Rearrangement of 2-alkylaminothiazoles to 2-amino-5-alkylthiazoles may also explain the observed products 2-aminothiazole with benzyl chloride yields first 2-benz Iaminothiazole (206). which then rearranges to 2-amino-5-benzvlthiazole (207) (Scheme 130) (163. 165. 198). [Pg.80]

Thiazolium derivatives unsubstituted at the 2-position (35) are potentially interesting precursors of A-4-thiazoline-2-thiones and A-4-thiazoline-2-ones. Compound 35 in basic medium undergoes proton abstraction leading to the very active nucleophilic species 36a and 36b (Scheme 16) (43-46). Special interest has been focused upon the reactivity of 36a and 36b because they are considered as the reactive species of the thiamine action in some biochemical reaction, and as catalysts for several condensation reactions (47-50). [Pg.375]

Mercury and tin in complexes (68 or 69) (Scheme 32 (154 mav behave as electrophilic centers (155. 156). Under basic conditions, the reactive species is an ambident anion (70) (Scheme 33). [Pg.394]

Like carbocations most free radicals are exceedingly reactive species—too reac tive to be isolated but capable of being formed as transient intermediates m chemical reactions Methyl radical as we shall see m the following section is an intermediate m the chlorination of methane... [Pg.172]

In this chapter you 11 see a number of processes m which the enol rather than the aide hyde or a ketone is the reactive species... [Pg.755]

Following the movement of airborne pollutants requires a natural or artificial tracer (a species specific to the source of the airborne pollutants) that can be experimentally measured at sites distant from the source. Limitations placed on the tracer, therefore, governed the design of the experimental procedure. These limitations included cost, the need to detect small quantities of the tracer, and the absence of the tracer from other natural sources. In addition, aerosols are emitted from high-temperature combustion sources that produce an abundance of very reactive species. The tracer, therefore, had to be both thermally and chemically stable. On the basis of these criteria, rare earth isotopes, such as those of Nd, were selected as tracers. The choice of tracer, in turn, dictated the analytical method (thermal ionization mass spectrometry, or TIMS) for measuring the isotopic abundances of... [Pg.7]

All of the reactions listed in Table 6.1 produce free radicals, so we are presented with a number of alternatives for initiating a polymerization reaction. Our next concern is in the fate of these radicals or, stated in terms of our interest in polymers, the efficiency with which these radicals initiate polymerization. Since these free radicals are relatively reactive species, there are a variety of... [Pg.350]

In discussing mechanism (5.F) in the last chapter we noted that the entrapment of two reactive species in the same solvent cage may be considered a transition state in the reaction of these species. Reactions such as the thermal homolysis of peroxides and azo compounds result in the formation of two radicals already trapped together in a cage that promotes direct recombination, as with the 2-cyanopropyl radicals from 2,2 -azobisisobutyronitrile (AIBN),... [Pg.352]

While this reaction with solvent continues to provide free radicals, these may be less reactive species than the original initiator fragments. We shall have more to say about the transfer of free-radical functionality to solvent in Sec. 6.8. [Pg.353]

Tacticity of products. Most solid catalysts produce isotactic products. This is probably because of the highly orienting effect of the solid surface, as noted in item (1). The preferred isotactic configuration produced at these surfaces is largely governed by steric and electrostatic interactions between the monomer and the ligands of the transition metal. Syndiotacticity is mostly produced by soluble catalysts. Syndiotactic polymerizations are carried out at low temperatures, and even the catalyst must be prepared at low temperatures otherwise specificity is lost. With polar monomers syndiotacticity is also promoted by polar reaction media. Apparently the polar solvent molecules compete with monomer for coordination sites, and thus indicate more loosely coordinated reactive species. [Pg.490]

Sonochemistry is also proving to have important applications with polymeric materials. Substantial work has been accomplished in the sonochemical initiation of polymerisation and in the modification of polymers after synthesis (3,5). The use of sonolysis to create radicals which function as radical initiators has been well explored. Similarly the use of sonochemicaHy prepared radicals and other reactive species to modify the surface properties of polymers is being developed, particularly by G. Price. Other effects of ultrasound on long chain polymers tend to be mechanical cleavage, which produces relatively uniform size distributions of shorter chain lengths. [Pg.263]

Thiothionyl Fluoride and Difluorodisulfane. Thiothionyl fluoride [1686-09-9] S=SF2, and difluorodisulfane [13709-35-8] FSSF, are isomeric compounds which may be prepared as a mixture by the action of various metal fluorides on sulfur vapor or S2CI2 vapor. Chemically, the two isomers are very similar and extremely reactive. However, in the absence of catalytic agents and other reactive species, FSSF is stable for days at ordinary temperatures and S=SF2 may be heated to 250°C without significant decomposition (127). Physical properties of the two isomers are given in Table 6. The microwave spectmm of S=SF2 has been reported (130). [Pg.244]

Shielding and Stabilization. Inclusion compounds may be used as sources and reservoirs of unstable species. The inner phases of inclusion compounds uniquely constrain guest movements, provide a medium for reactions, and shelter molecules that self-destmct in the bulk phase or transform and react under atmospheric conditions. Clathrate hosts have been shown to stabiLhe molecules in unusual conformations that can only be obtained in the host lattice (138) and to stabiLhe free radicals (139) and other reactive species (1) similar to the use of matrix isolation techniques. Inclusion compounds do, however, have the great advantage that they can be used over a relatively wide temperature range. Cyclobutadiene, pursued for over a century has been generated photochemicaHy inside a carcerand container (see (17) Fig. 5) where it is protected from dimerization and from reactants by its surrounding shell (140). [Pg.75]

Figure 4b represents the case where a reactant dissolved in the dispersed phase reacts with the continuous phase to produce a co-reactant. The co-reactant and any remaining unreacted original reactant left in the dispersed phase then proceed to react with each other at the dispersed phase side of the interface and produce a capsule shell. Capsule shell formation occurs entirely because of reaction of reactants present in the droplets of dispersed phase. No reactant is added to the aqueous phase. As in the case of the process described by Figure 4a, a reactive species must be dissolved in the core material in order to produce a capsule shell. [Pg.320]

R is rate of reaction per unit area, a is interfacial area per unit volume, S is solubiHty of solute in continuous phase, D is diffusivity of solute, k is rate constant, kj is mass-transfer coefficient, is concentration of reactive species, and Z is stoichiometric coefficient. When Dk is considerably greater (10 times) than Ra = aS Dk. [Pg.430]


See other pages where Species reactive is mentioned: [Pg.79]    [Pg.791]    [Pg.934]    [Pg.934]    [Pg.2126]    [Pg.2439]    [Pg.2451]    [Pg.2927]    [Pg.2927]    [Pg.2928]    [Pg.2930]    [Pg.2936]    [Pg.2937]    [Pg.2937]    [Pg.31]    [Pg.71]    [Pg.1270]    [Pg.34]    [Pg.381]    [Pg.425]    [Pg.266]    [Pg.494]    [Pg.376]   
See also in sourсe #XX -- [ Pg.19 ]

See also in sourсe #XX -- [ Pg.145 ]

See also in sourсe #XX -- [ Pg.256 ]

See also in sourсe #XX -- [ Pg.2 ]

See also in sourсe #XX -- [ Pg.39 ]




SEARCH



Accumulation of Reactive Species

Aerobic organisms reactive oxygen species

Alcohol oxidation species reactivity

Antibodies species reactivity

Antioxidant mechanisms reactive oxygen species

Antioxidant properties reactive oxygen species

Apoptosis reactive oxygen species

Aqueous solutions reactive oxygen species

Arachidonic acid reactive oxygen species

Aromaticity metal aromatic species reactivity

Arsenic reactive oxygen species

Assay reactive oxygen species

By Reactive Nitrogen Species

Cancer reactive oxygen species

Cardiovascular disease reactive oxygen species

Cardiovascular systems, reactive oxygen species

Cell signaling, reactive nitrogen species

Chemical reactions reactive species

Chemical species reactivity

Chemically Reactive Species

Covalent active species reactivities

Cytochrome reactive species

Deoxyribonucleic acid reactive oxygen species

Detection of Reactive Species

Detoxification, reactive oxygen species

Diprotonated species, electrophilic reactivities

Electrolytes reactive oxygen species production

Electron reactive oxygen species

Free radical reactive intermediates species

Free radicals Reactive oxygen species

Free radicals reactive nitrogen species

Generate reactive oxygen species

Generation and Detoxication of Reactive Oxygen Species

Generation of Reactive Onium Carbanion Species

Generation of reactive species

Glutamate receptors reactive oxygen species

High density reactive species

Hydrogen peroxide reactive oxygen species

Hypoxia-ischemia reactive oxygen species

Imaging reactive oxygen species

Induction of Reactive Oxygen Species

Interconversion Between Reactive Species

Isomerism reactive species

Light-generated reactive species

Lipoxygenase reactive species produced

Metabolism reactive species formation

Mitochondria reactive oxygen species

Myocardial ischemia, reactive oxygen species

Non receptor triggers reactive oxygen species and nitric oxide

Non-reactive species

Onium reactive species

Oxidative metabolism reactive species formation

Oxidative stress reactive oxygen species

Oxidative/nitrosative stress Reactive oxygen species

Oxo-Titanium Species and Reactive Intermediates

Phagocytes reactive oxygen species produced

Phagocytes reactive oxygen species production

Photochemistry reactive oxygen species

Photogenerated reactive species

Polymers reactive species

Potent reactive oxygen species

Primary and Secondary Reactive Species

Protein oxidation reactive oxygen species reactivity with amino

Radicals, Electrophiles, and Other Reactive Species

Reaction Products and Reactive Species

Reaction modeling reactive oxygen species

Reactive Intermediates Iron and Copper Species

Reactive Oxygen Species and EPO Expression

Reactive Oxygen Species and Toxicity

Reactive Species from Solution by Reversible Encapsulation

Reactive Species with Fe-oxo Motifs

Reactive carbonyl species

Reactive chlorine species

Reactive cross-linking species

Reactive cyclopropane species

Reactive halogen species,

Reactive intermediate-mediated species

Reactive intermediates anionic species

Reactive intermediates cationic species

Reactive intermediates radical species

Reactive nitrogen oxide species

Reactive nitrogen species

Reactive nitrogen species , reactivity

Reactive nitrogen species induced injury

Reactive nitrogen species lipid modification

Reactive nitrogen species lipid oxidation

Reactive nitrogen species, muscle

Reactive onium carbanion species

Reactive onium carbanion species generation

Reactive oxide species

Reactive oxygen and nitrogen species

Reactive oxygen species

Reactive oxygen species , basic properties

Reactive oxygen species , chromium

Reactive oxygen species , heat shock response

Reactive oxygen species , nitric oxide

Reactive oxygen species , nitric oxide chemical biology

Reactive oxygen species . See

Reactive oxygen species . skin damage

Reactive oxygen species 684 / INDEX

Reactive oxygen species Candida albicans

Reactive oxygen species Lipid peroxidation

Reactive oxygen species MAPK activation

Reactive oxygen species Quenching

Reactive oxygen species Superoxide)

Reactive oxygen species activate transcription factors

Reactive oxygen species alcohol

Reactive oxygen species and

Reactive oxygen species and antioxidants

Reactive oxygen species biosynthesis

Reactive oxygen species blockers

Reactive oxygen species cell culture

Reactive oxygen species cellular production

Reactive oxygen species chemical reactivity

Reactive oxygen species defence mechanisms

Reactive oxygen species deleterious effects

Reactive oxygen species diseases

Reactive oxygen species enzymes

Reactive oxygen species examples

Reactive oxygen species flavonoids

Reactive oxygen species fluorescent probes

Reactive oxygen species formation

Reactive oxygen species generation

Reactive oxygen species glutamate-mediated generation

Reactive oxygen species glutathione

Reactive oxygen species hepatic generation

Reactive oxygen species hepatotoxicity

Reactive oxygen species hydroxyl radical

Reactive oxygen species in plants

Reactive oxygen species induced

Reactive oxygen species induced injury

Reactive oxygen species inhibitors

Reactive oxygen species interactions

Reactive oxygen species kidneys

Reactive oxygen species methods

Reactive oxygen species mtDNA mutations

Reactive oxygen species organic radicals

Reactive oxygen species overproduction

Reactive oxygen species overview

Reactive oxygen species oxidative stress, contribution

Reactive oxygen species peroxidation

Reactive oxygen species peroxynitrite

Reactive oxygen species plants

Reactive oxygen species produced

Reactive oxygen species production

Reactive oxygen species quencher

Reactive oxygen species quenching mechanism

Reactive oxygen species radiation

Reactive oxygen species radicals

Reactive oxygen species reaction with carotenoids

Reactive oxygen species reactions

Reactive oxygen species reactions, overview

Reactive oxygen species receptor tyrosine kinases

Reactive oxygen species redox reactions leading

Reactive oxygen species relative reactivity

Reactive oxygen species retention

Reactive oxygen species roles

Reactive oxygen species scavenging effect

Reactive oxygen species sensing

Reactive oxygen species sensing chemicals

Reactive oxygen species silica

Reactive oxygen species sources

Reactive oxygen species toxicity

Reactive oxygen species treatment

Reactive oxygen species visualization

Reactive oxygen species vitamin

Reactive oxygen species water interactions

Reactive oxygen species with small molecules

Reactive oxygen species xenobiotics

Reactive oxygen species, ROS

Reactive oxygen species, oxidative stress induced

Reactive oxygen species, riboflavin

Reactive oxygen/nitrogen species

Reactive radical species

Reactive short-lived species

Reactive species Lewis structures

Reactive species accumulation

Reactive species basicity

Reactive species continuous generation

Reactive species formation

Reactive species generation

Reactive species hydrated electron

Reactive species hydrogen atom , reactivity

Reactive species hydroperoxide anion

Reactive species hydroperoxyl radical

Reactive species hydroxyl radical

Reactive species isolation, from reversible

Reactive species photochemical dissociation

Reactive species reactivity

Reactive species reactivity

Reactive species singlet oxygen atom

Reactive species titration

Reactive species triplet oxygen atom

Reactive species, metabolism, fate

Reactive species, stoichiometric relationship

Reactive species, transfer

Reactive sulfur species

Reactive surface intermediate species

Reactive surface intermediate species measurement

Reactivity of Surface Methoxy Species

Reactivity, mononuclear oxygen species,

Redox-activated reactions chemically reactive species

Role of Reactive Oxygen Species

Role of Reactive Oxygen Species in PSII Dynamics

Scavengers reactive oxygen species

Secondary reactive species

Semen, reactive oxygen species

Signaling reactive oxygen species

Singlet molecular oxygen Reactive species)

Skin inflammation reactive oxygen species

Sol-Gel Encapsulation of Reactive Species

Stabilization of reactive species

Structure and Bonding in Some Highly Reactive Species

Styrene reactive oxygen species

Superoxide dismutase reactive oxygen species

Superoxide reactive species

Target Areas for Reactive Species

Terpene QMs and Reactive Oxygen Species

The Reactivity of Chemical Species

The Role of Reactive Oxygen and Nitrogen Species

Transfer of Reactive Species

Use of Short-Lived Reactive Species Achieved by High-Resolution Reaction Time Control

Vascular systems reactive oxygen species

© 2024 chempedia.info