Unsaturated aliphatic radicals

Examples of cyclization involving thiyl radicals leading to bicyclic compounds in the Cy5/Cy6 case have been also recorded. From the behavior of unsaturated aliphatic radicals one would expect to obtain a mixture of (Cy5) and (Cy6) products. In fact, the examples recorded and discussed in... 

Clearly, whether or not ozone is formed depends also on the rate at which, for example, unsaturated hydrocarbons react with it. Rates of reactions of ozone with alkanes are, as noted above, much slower than for reaction with OH radicals, and reactions with ozone are of the greatest significance with unsaturated aliphatic compounds. The pathways plausibly follow those involved in chemical ozonization (Hudlicky 1990). 

Addition of 0- to double bonds and to aromatic systems was found to be quite slow. Simic et al. (1973) found that O- reacts with unsaturated aliphatic alcohols, especially by H-atom abstraction. As compared to O, HO reacts more rapidly (by two to three times) with the same compounds. In the case of 1,4-benzoquinone, the reaction with O consists of the hydrogen double abstraction and leads to the 2,3-dehydrobenzoquinone anion-radical (Davico et al. 1999, references therein). Christensen et al. (1973) found that 0- reacts with toluene in aqueous solution to form benzyl radical through an H-atom transfer process from the methyl group. Generally, the O anion-radical is a very strong H-atom abstractor, which can withdraw a proton even from organic dianions (Vieira et al. 1997). 

Alkylidene. A divalent organic radical derived from an unsaturated aliphatic hydrocarbon eg, ethylidene (Hs C. CH =), poopylidene, (CHjCHjCH") etc Alkylideneperoxide. The name coined by... 

Hydroxyl radicals, OH, can undergo several types of reactions with chemical species in aqueous solution. The types of reactions that are likely to occur are hydroxylation, hydrogen abstraction, electron transfer, and radical-radical recombination. Hydroxylation reaction occurs readily with aromatic and unsaturated aliphatic compounds, which result in the formation of hydrox-ylated radicals ... 

Acyclics Name the acyclic hydrocarbon terpene radicals systematically in a manner similar to that for other unsaturated aliphatic hydrocarbon radicals (IUPAC rules) when pure compounds are involved. Examples ... 

Addition reactions occur readily with aromatic and unsaturated aliphatic compounds. The resulting compounds are hydroxylated radicals ... 

Generation of Carbonyl Radical Ions by Electron Transfer 459 Table 2. Reduction potentials of some saturated and unsaturated aliphatic aldehydes and ketones. ... 

The hydrocarbon part of the surfactant can be a straight-chain aliphatic radical, as in the case of sodium dodecyl sulphate given above, as well as a branched-chain, unsaturated radical, and can involve benzene or phenolic residues and polar groups ... 

Vorlander described unsaturated polyesters which were produced from ethylene glycol and maleic anhydride in 1894,- but commercial unsaturated polyesters were not Introduced until the 1920 s. The first commercial free radical-curable unsaturated polyesters were produced by Klenle and Hovey, who condensed dlfunctlonal glycols, such as ethylene glycol with phthalic anhydride and an unsaturated aliphatic acid such as oleic acid.- — - The name alkyd, which was derived from the prefix in alcohol and the suffix in incorrectly spelled "akyd" was used to describe these important polyesters. 

Aromatic hydrocarbons are known to be important in soot formation in flames. The aromatic structure may abet molecular growth leading to PAH and soot formation through its ability to stabilize radicals formed from addition of aromatic radicals to unsaturated aliphatics such as acetylenic species (jL>2.). Accordingly, both aromatics and unsaturated aliphatics would be important for growth processes. Both types of species are prevalent in the flame zone where growth occurs. Aromatic structures with unsaturated side chains also are observed there (1 >3). 

In this section, studies on the reactions of naphthyl radicals with unsaturated aliphatic hydrocarbons toward the production of three fused rings and of aliphatic residues attached to naphthalene are described. This is an effort to examine the process of polycyclic aromatic hydrocarbon (PAH) growth [88-99]. The source of naphthyl radicals for the experimental study was naphthyl iodide, in view of its low C—I bond dissociation energy. It dissociates very fast following the reflected shock heating. The unsaturated aliphatic hydrocarbons that have been studied were ethylene [28] and acetylene [29]. 

Unsaturated poly(ester amide) resins were also prepared by reaction between diglycidyl ether of bisphenol-A-based epoxy and unsaturated aliphatic bisamic acids, using a base catalyst (Fig. 5.4). These resins were then blended with styrene to produce homogeneous resin syrups which were cured by using BPO as the free radical initiator. 

The reaction capability of PS is weak, but the reaction capability can be improved by anchoring the functional group to the aliphatic chain or aromatic ring of PS using chemical or conversion reactions. Aliphatic chain reactions are halogenation reactions, oxidation reactions, or unsaturated acids to bonded aliphatic chain of PS (in the presence of a radical catalysis). 

A more practical, atom-economic and environmentally benign aziridination protocol is the use of chloramine-T or bromamine-T as nitrene source, which leads to NaCl or NaBr as the sole reaction by-product. In 2001, Gross reported an iron corrole catalyzed aziridination of styrenes with chloramine-T [83]. With iron corrole as catalyst, the aziridination can be performed rmder air atmosphere conditions, affording aziridines in moderate product yields (48-60%). In 2004, Zhang described an aziridination with bromamine-T as nitrene source and [Fe(TTP)Cl] as catalyst [84]. This catalytic system is effective for a variety of alkenes, including aromatic, aliphatic, cyclic, and acyclic alkenes, as well as cx,p-unsaturated esters (Scheme 28). Moderate to low stereoselectivities for 1,2-disubstituted alkenes were observed indicating the involvement of radical intermediate. 

Acroleins and u,(i-unsaturated ketones are coupled with aliphatic aldehydes in the Cr-catalyzed diastereoselective coupling in the presence of Mn and MesSiCl [60]. As shown in Scheme 24, the generated radical species undergoes the further one-electron reduction to afford the corresponding al-lylchromium 41, which reacts with the aldehyde to give the corresponding... 

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