Electron attack

The n electrons attack the electrophile, the positive part of the reagent, usually the H , and form a carbocation intermediate. 

Mechanism. The double bond ti electrons attack the electrophile. Protonation of the double bond yields a secondary carbocation inter mediate. The bromine nucleophile attacks the carbocation to form 2-bromopropane. 

The excited electron may interact with any other odd or unpaired electron attacking agent and form a bond, as soon as the orbit begins to overlap with that of the excited molecule due to increase in electron affinity. 

ScholesG, Willson RL, Ebert M (1969) Pulse radiolysis of agueous solutions of deoxyribonudeotides and of DNA reaction with hydroxy-radicals. Chem Commun 17-18 Schuchmann MN, von Sonntag C (1982) Flydroxyl radical induced oxidation of diethyl ether in oxygenated aqueous solution. A product and pulse radiolysis study. J PhysChem 86 1995-2000 Shragge PC, Michaels FIB, Flunt JW (1971) Factors affecting the rate of hydrated electron attack on polynucleotides. Radiat Res 47 598-611... 

Visscher KJ, de Haas MP, Loman H, Vojnovic B, Warman JM (1987) Fast protonation of adenosine and of its radical anion formed by hydrated electron attack a nanosecond optical and dc-conduc-tivity pulse radiolysis study. Int J Radiat Biol 52 745-753 Visscher KJ, Spoelder HJW, Loman H, Hummel A, Horn ML (1988) Kinetics and mechanism of electron transfer between purines and pyrimidines, their dinucleotides and polynucleotides after reaction with hydrated electrons a pulse radiolysis study. Int J Radiat Biol 54 787-802 von Sonntag C (1980) Free radical reactions of carbohydrates as studied by radiation techniques. Adv Carbohydr Chem Biochem 37 7-77... 

Hydrolysis is part of the larger class of chemical reactions called nucleophilic displacement reactions in which a nucleophile (electron-rich species with an unshared pair of electrons) attacks an electrophile (electron deficient), cleaving one covalent bond to form a new one. Hydrolysis is usually associated with surface waters but also takes place in the atmosphere (fogs and clouds), groundwater, at the particle-water interface of soils and sediments, and in living organisms. 

Scheme 10). In this compound one pyrrole ring was isomerized by shifting the attachment of the chain from the a- to the (3-position GV-confused) while the formal tetravalent oxidation state is provided by the presence of the ethoxide group. The origin of the LiOEt unit is the result of a one-electron attack on thf followed by H abstraction, which accounts for the tetravalent state of uranium in the product. 

The reaction mechanism of alkoxymercuration/demercuration of an alkene is similar to other electrophilic additions we have studied. First, the cyclopentene n electrons attack Hg2+ with formation of a mercurinium ion. Next, the nucleophilic alcohol displaces mercury. Markovnikov addition occurs because the carbon bearing the methyl group is better able to stabilize the partial positive charge arising from cleavage of the carbon-mercury bond. The ethoxyl and mercuric groups are trans to each other. Finally, removal of mercury by NaBH4 by a mechanism that is not fully understood results in the formation of 1-ethoxy-1-methylcyclopentane. 

Intramolecular radical capture was observed when a 19-CH2 radical (17) was generated by irradiation of corticosterone 21-acetate ii nitrite (16 [14]. In addition to the i8-oxime (20 21% yield), the 4-oximinO 5j5,19-cyclo-steroids (19 two oxime isomers) were major products (45%). These arose through sr-electron attack on the 19-CH2 radical to form the... 

Most of the electron attacks eventually lead to anti addition of hydrogen to the triple bond. Therefore, it has often been assumed that a irons dianion is a necessary intermediate. Because both free dianions and dimetal adducts may be isolated or detected, either or both may be important in different systems. 

This type of coiled conformation, in which a certain number of monomer units are present in a certain number of turns, would cause the terminal carbon atom of a free radical, formed by the scission of a carbon-carbon bond in the polymer chain backbone, to be in close proximity to, and to interact with, a specific carbon atom, or a hydrogen atom linked to a specific carbon atom, in the turn. Thus, in an isotactic polyethylene molecule, which contains three monomer units per turn and is represented by the structure in Fig. 2, the scission of the Qg - Cm bond would bring C 6 in close proximity to or C 2 or the hydrogen atoms linked to any one of them. If Qe containing the unpaired electron attacks the C i, a six-membered ring may be formed feq. (15)]. It has been observed that in an intramolecular cyclization, the fastest reactions are those which proceed via six-membered rings However, cyclohexane (I) may lose one or more hydrogen atoms to a free radical and form hexene, hexadiene, hexane, and other compounds as shown below. 

Alkene ir electrons attack bromine, pushing out bromide ion and leaving a bromo carbocation. 

Nucleophilic alkyl radicals, i.e. c-C6Hir or t-Bu% add to activated alkynes 3.0-5.2 times slower than the corresponding substituted alkenes, whereas nucleophiles having lone pairs of electrons attack alkynes markedly faster than alkenes. Application of Frontier Orbital theory indicates early and late transition states for radical nucleophiles and nonradical nucleophiles, respectively. ... 

Hydrolysis is an example of a larger class of reactions referred to as nucleophilic displacement reactions in which a nucleophile (an electron-rich species containing an unshared pair of electrons) attacks an electrophilic atom (an electron-deficient reaction center). Hydrolytic processes encompass several types of reaction mechanisms that can be defined by the type of reaction center (i.e., the atom bearing the leaving group, X) where hydrolysis occurs. The reaction mechanisms encountered most often are direct and indirect nucleophilic substitution and nucleophilic addition-elimination. 

The Cg-Cj bond is situated at the rear side of the ionizable group and the a electrons attacks the carbon bearing the ionizable group, thus facilitating the ionization. This leads to a nonclassical carbenium ion, which reacts with acetic acid to yield the racemic mixture of acetates. No such anchimeric assistance is available to the endo-isomer, which undergoes slow acetolysis through classical carbenium ions. 

Electronic countermeasures (ECM) or electronic attack (EA) are those actions taken to reduce the enemy s effective use of the electromagnetic spectrum. These actions may include jamming, electronic deception, false targets, chaff, flares, transmission disruption, and changing tactics. 

The radical, which is unstable because of its unpaired electron, attacks a carbon atom on an ethylene molecule. This is the initiation of the reaction. 

Fuel Cell Requirements for Electronic Attack Drones... 

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