Radicals additive names

There may be a third effect influencing the rate of radical addition, namely steric hindrance to product formation associated with resistance of groups to move into the direction of the initial conformation of the addition product. Examples of this effect appear in the addition of methyl radical to methyl substituted ethylenes as seen in Table II (13). The relative rates are ethylene (1.0), propylene (0.7), cis and trans- 2-butene (0.23 and 0.33), 1,1-dimethylethylene (1.1), trimethylethylene... 

The stereospecificity of the methylene transfer provides compelling support for a concerted mechanism and this conclusion has rarely been disputed. It is instructive, however, to review the experimental evidence that allowed for the elimination of the alternative mechanistic proposals, namely, a radical addition and a carbome-tallation (Scheme 3.4). 

Acrylamide polymerization by radiation proceeds via free radical addition mechanism [37,38,40,45,50]. This involves three major processes, namely, initiation, propagation, and termination. Apart from the many subprocesses involved in each step at the stationary state the rates of formation and destruction of radicals are equal. The overall rate of polymerization (/ p) is so expressed by Chapiro [51] as ... 

The free radical additions of sulfonyl halides to alkenes, catalyzed by light or typical chemical radical initiators (In), were first investigated in the 1950s. The products which are jS-halo sulfones (22) were obtained via a chain reaction in which RSO2 acts as the chain carrier, namely ... 

A -hexenyl substituent, extensive cyclization occurs to yield the cyclopentylcarbinyl product from the yields of uncyclized and cyclized products for A -hexenylmercury chloride, the rate constants for equation 50 have been estimated vide supra). The 5 2 reaction 49 has also been invoked to be the key step in the alkylation of -substituted styrenes by a free-radical addition-elimination sequence, namely ... 

The same group recently disclosed a related free radical process, namely an efficient one-pot sequence comprising a homolytic aromatic substitution followed by an ionic Homer-Wadsworth-Emmons olefination, for the production of a small library of a,/3-unsaturated oxindoles (Scheme 6.164) [311]. Suitable TEMPO-derived alkoxy-amine precursors were exposed to microwave irradiation in N,N-dimethylformam-ide for 2 min to generate an oxindole intermediate via a radical reaction pathway (intramolecular homolytic aromatic substitution). After the addition of potassium tert-butoxide base (1.2 equivalents) and a suitable aromatic aldehyde (10-20 equivalents), the mixture was further exposed to microwave irradiation at 180 °C for 6 min to provide the a,jS-unsaturated oxindoles in moderate to high overall yields. A number of related oxindoles were also prepared via the same one-pot radical/ionic pathway (Scheme 6.164). 

How do matters stand with radical addition A comparison of Ee0 and re with the energy of dissociation of the resulting bond De showed that this influence certainly does exist [41-46]. The parameters Ee0 and re are juxtaposed with the dissociation energy of the bond formed Z>e(X—C) in Table 6.21. For reactions of one class, namely, X + CH2=CHY, the linear correlation Ee0 = const x [De(X—C)]2 holds const = 5.95 x 10 4mol kJ 1. The following linear correlation was found to be fulfilled for the reactions of all the 13 classes considered (see Figure 6.6) ... 

Dienamides such as 167 react by a different reaction pathway168, namely by addition of the amide oxygen to the alkene by a radical addition reaction (equation 111). 

The Sjjf.fl character of the reaction was ascertained by the effect of light irradiation and addition of a radical trap. Namely, under light irradiation, the half-reaction time was considerably shortened (3 instead of 41 min). Addition of di(tert-butyl)nitroxide completely quenched the reaction—neither C- nor 0-substitution was observed after 4 h. The radical trap may only react with the R radicals that escaped the solvent cage where R, Nu, and X have been formed. This means that, in the... 

Write the name and structure of one of the common Initiators used In free radical addition pol5mierIsatIon. 

These rules now apply whether the anion is a radical or not, leading to changes to Ref. 22 for additive names of certain radical anions. For example, HSSH - was named bis(hydridosulhde)(5-5)( l—)22 but is here named bis(hydridosulfate)(5-5)( l—). 

Heteropolyatomic cations are usually named either substitutively (see Section IR-6.4) or additively (see Chapter IR-7). Substitutive names do not require a charge number, because the name itself implies the charge (Examples 2 and 4 below). Radical dots may be added to additive names to indicate the presence of unpaired electrons. 

This section presents names of ions and radicals that can be formally derived from hydrides by the operations of removal or addition of hydrogen atoms, hydride ions or hydrons. A great many ions and radicals can also be named by additive methods, as described in Chapter IR-7. Many simple ions and radicals are named in Table IX, often by both nomenclature types. 

IR-7.1.2 Choosing a central atom or atoms, or a chain or ring structure IR-7.1.3 Representing ligands in additive names IR-7.1.4 Ions and radicals IR-7.2 Mononuclear entities IR-7.3 Polynuclear entities... 

Anionic species take the ending ate in additive nomenclature, whereas no distinguishing termination is used for cationic or neutral species. Additive names of ions end with the charge number (see Section IR-5.4.2.2). In additive names of radicals, the radical character of the compound may be indicated by a radical dot, , added in parentheses and centred, after the name of the compound. Polyradicals are indicated by the appropriate numeral placed before the dot. For example, a diradical is indicated by (2 ) . 

First of all What is an ATRP It is a name given to a CRP process that displays similarities to the activation and deactivation steps occurring in catalytic Atom Transfer Radical Addition reactions. (14)... 

Since emulsion polymerization is a free-radical addition polymerization, all the kinetic events, namely, initiation, propagation, termination and transfer reactions which have already been described in Chapter 1, are applicable to describe the overall rate of the polymerization and molar mass development of the latex polymer. However, the heterogeneous nature of the polymerization adds some complications due to partitioning of the various ingredients between the phases ... 

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