N-hexyl radical

Schmid and Ingold (1978) extended their investigation by allowing pairs of spin traps to compete for n-hexyl radicals (from bis-heptanoyl peroxide). It was emphasized that the error limits in these experiments were large (ca. 30%), since the onset of the decay of certain spin adducts was evident at very low adduct concentrations. 

Analogous results obtain in intermolecular addition of alkyl radicals to unsaturated amides. Thus addition of n-hexyl radical to the unsaturated amide 4 derived from (S,S)-1 results in four products, two by addition a to the ketone and two by addition a to the amide enol. The former products are formed with slight selectivity, (60 40), but the latter products (5) are formed in ratio of 93 7.3... 

The occurrence of energy transfer has been confirmed by preliminary determinations of the yield of hydrocarbon products formed (15). The dependence of the yields of various products on the amount of n-hexane shows a rapid increase at low hydrocarbon electron fractions. The curves then flatten out demonstrating that the active sites on the silica gel surface have been used up. There is a difference in saturation behavior for various hydrocarbon products the combination of two n-hexyl radicals to form n-dodecane indicates a saturation at an electron fraction of 0.05, whereas the formation of 5-methylundecane from n-hexyl and 2-hexyl radicals reaches saturation first at the electron fraction of 0.2. The same general behavior is observed also for Ci0, C9, and C8 products. 

Silyl radicals generated from both phenyl and n-hexyl substituted poly-(hydrosilane)s add readily to a variety of compounds containing C = C and 0 = C moieties to give the corresponding radical adducts for which EPR spectra have been recorded. ... 

In addition, Kozuka and Lewis measured the tritium isotope effect for the reaction between the n -hexyl, the 2-hexyl and the 2-methy 1-2-pentyl radicals with triphenyltin hydride and triphenyltin hydride-t see the last three entries in Table 11. The isotope effect of 2.55 found for the triphenyltin hydride-w-hexyl radical reaction was slightly smaller... 

Coordination copolymerization of ethylene with small amounts of an a-olefin such as 1-butene, 1-hexene, or 1-octene results in the equivalent of the branched, low-density polyethylene produced by radical polymerization. The polyethylene, referred to as linear low-density polyethylene (LLDPE), has controlled amounts of ethyl, n-butyl, and n-hexyl branches, respectively. Copolymerization with propene, 4-methyl-1-pentene, and cycloalk-enes is also practiced. There was little effort to commercialize linear low-density polyethylene (LLDPE) until 1978, when gas-phase technology made the economics of the process very competitive with the high-pressure radical polymerization process [James, 1986]. The expansion of this technology was rapid. The utility of the LLDPE process Emits the need to build new high-pressure plants. New capacity for LDPE has usually involved new plants for the low-pressure gas-phase process, which allows the production of HDPE and LLDPE as well as polypropene. The production of LLDPE in the United States in 2001 was about 8 billion pounds, the same as the production of LDPE. Overall, HDPE and LLDPE, produced by coordination polymerization, comprise two-thirds of all polyethylenes. 

Problem 6.48 Write the initiation and the propagation steps for a free-radical-catalyzed (RO-) addition of CH,CH=0 to 1-hexene to form methyl n-hexyl ketone,... 

Therefore, one might expect similar long-range charge transfer effects in the radiolysis of solid n-hexane. In irradiated hexane possible electron donors to the hexane ion radical are the hexenes, dimers, and hexyl radicals, all of which have lower ionization potentials than n-hexane. Additives of lower ionization potential than n-hexane would also be expected to act as electron donors. Another approach is to use a material that has a higher ionization potential than n-hexane to form a mixture in which the n-hexane fraction is sma l and to study the effects produced by charge transfer to the n-hexane. 

Maccoll et have pointed out that along the series of primary bromides (n-propyl, n-butyl, n-pentyl, n-hexyl) the chain component of the overall thermal decomposition undergoes a steady decrease relative to the unimolecular component of the decomposition. This has been attributed to the increased probability of formation of -radicals with increase in the length of the carbon chain in the molecule. The decomposition of secondary monobromides is mainly unimolecular with only a slight radical-chain component. Tertiary monobromides decompose uni-molecularly. 

Femtosecond photodissociation dynamics of nitroethane and l-nitropropane have been studied in the gas phase and in solution by resonance Raman spectroscopy, with excitation in the absorption band around 200 nm. At such short time-scales it is possible to detect changes in the two N-O bond lengths in the Franck-Condon region, prior to C-N bond cleavage. Photolyses of nitroalkanes at 193 nm have been monitored by photoionization of the fragments and time-of-flight mass spectrometry. Both C-N and N-O bond dissociation pathways are observed and, under the conditions of free jet expansion, primary products such as pentyl and hexyl radicals are stabilized and can be detected. 

The formation of radical R" explains the lack of stereoselectivity in formation of RMgX (X = Cl, Br) from anti- and syn-7-halogenobenzonorbornadiene, but delds vary ( 95 % from anti-RX 32-36 % from syn) . This method also may be applied when R = n-hexyl (85 %) and R = norborn-2-en-7-yl (yield of syn -l- anti RMgX is > 19 %) . A solution of NaCioHg in THF is added dropwise to RX and MgX2 (X = Cl, Br) in THF, and at the end point of the reaction the deep-green color of NaCigHg persists . ... 

There is much more solvent attack than was claimed for I bromo-1-methyl-2.2-diphcnylcyclo-propane 20. Instead, the extent of s agrees with that for eyelopropyl bromide itself 52.98. Together with the linding that there is less than 0.52 s in a reaction ol n-hexyl bromide in Did 52. these linding disprove a set of hypotheses suggested by Walborsky I09 (a) the only radicals that attack the solvent are those that desorb (b) their inevitable fate is solvent attack and (c) fewer eyelopropyl radicals than typical alkyl radicals desorb. These hypotheses predict more solvent attack in reactions of typical alkyl than eyelopropyl halides, opposite from observations 52. ... 

Bank, S. and D. A. Juckett. 1976. Reactions of aromatic radical anions. 12 kinetic studies of the reaction of radical anions of varying reduction potential with n-hexyl bromides, iodides, and chlorides, J. Am. Chem. Soc., 98 7742-7746. 

In order to study elastomeric networks, simulating the type of polymers used for tires, we switched to polymers with low glass transition temperatures and oligoether bis-maleimides. A typical random copolymer structure, built from the radical copolymerization of n-hexyl acrylate and 2-furfuryl methacrylate, is shown below. These reactions were conducted in toluene at 80°C with AIBN as initiator. After 8 h, the copolymers were recovered by precipitation in 70 to 80% yields. The compositions varied fi om 2 to 30% of the furanic monomer (monomer feed and copolymer composition were always very similar, suggesting that ri and ti must have both been close to unity). The corresponding Tgs went from -70 to 30°C for molecular weights of about 20,000. Both homopolymers were also prepared as reference materials. 

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