Dimethyl-2,2-azobis

Although radical chain processes occur spontaneously at moderate temperatures, it is usually desirable to faciliate the chain propagation by addition of an initiator. 2,2 - Azobi-sisobutyronitrile (AIBN = 2,2 -dimethyl-2,2 -azobis[propanenitrile]) is an ideal initiator, its decomposition rate is solvent independent. Such a reaction is described for a prototype 5-hexenylbromide with tributyltin hydride initiated by In [23] as an illustration in Scheme VII/10. 

A reaction flask was charged with 2-ethyl-2-adamantyl methacrylate (0.24 mol), p-acetoxystyrene (0.56 mol), and isopropanol (279 g) and then heated to 75°C. This mixture was next treated with dimethyl-2,2 -azobis(2-methylpropionate) (0.048 mol) dissolved in isopropanol (22.11 g), stirred 20 minutes, and finally refluxed for... 

Similar data obtained upon phot, of l,l -azobis(l-cyanocyclohexane) or dimethyl-2,2 - azobis(2-methyIpropanoate) in styrene. ) da/dT = + 2-10" TK" ... 

In the case of electrostatic interactions, lower temperatures of polymerization are known to increase the stability of monomer-template assemblies. Choose the initiators that allow you to work at lower temperatures (for example 2,2 -azobis(4-methoxy-2,4-dimethylvaleronitrile) and 2,2 -azobis(2,4-dimethylvaleronitrile) by Wako (V-70 and V-65) or photo-polymerize with AIBN (azobisisobutyronitrile) at 15°C with UV light). An environmentally friendly alternative to AIBN is dimethyl 2,2 -azobis(2-methylpropionate)(V-601 manufactured by Wako). Thermally initiated polymerization has a more general scope and may be preferable in certain monomer-template systems. These systems have been critically compared for the imprinting of terbutylazine [6]. 

N,N-Dimethyl-p-azoaniline. See4-Dimethylaminobenzene Dimethyl 2,2 -azobisisobutyrate. See Dimethyl 2,2 -azobis (2-methylpropionate)... 

V-154L. See Benzene, mono-CI0-13-alkyl derivs., distillation residues V-159L. SeeC12-14alkylbenzene V-501. See 4,4 -Azobis (4-cyanopentanoic acid) V-511. See Zinc phosphate V-601. See Dimethyl 2,2 -azobis (2-methylpropionate)... 

Azobis (2-methyl-N-phenylpropionamidine) dihydrochloride 2,2 -Azobis (2-methylpropane) 2,2 -Azobis (2-methylpropionamide) dihydrate 2,2 -Azobis [N-(2-propenyl)-2-methylpropionamide] 2,2 -Azobis [2-(3,4,5,6-tetrahydropyrimidin-2-yI) propane] dihydrochloride 2,2 -Azobis (2,4,4-trimethylpentane) n-Butyl-4,4-bis (t-butylperoxy) valerate t-Butyl hydroperoxide t-Butyl peroxycrotonate t-Butyl peroxyneoheptanoate Cerium Cumene hydroperoxide Cumyl peroxyneodecanoate o-Cumylperoxyneoheptanoate 1 -[(1 -Cyano-1 -methylethyl) azo] formamide Decanoyl chloride Decanoyl peroxide Di-t-amyl peroxide 2,2-Di (t-butylperoxy) butane Dicetyl peroxydicarbonate Dicyclohexyl peroxydicarbonate Dimethyl 2,2 -azobis (2-methylpropionate) 2,5-Dimethyl-2,5-di (benzoylperoxy) hexane 2,5-Dimethylhexane-2,5-dihydro peroxide Dimyristyl peroxydicarbonate Di-n-propyl peroxydicarbonate Ethyidibutylperoxybutyrate 3,3,6,6,9,9-Hexamethyl 1,2,4,5-tetraoxa cyclononane Lauroyl chloride Pelargonyl peroxide, 2-Phenylazo-4-methoxy-2,4-dimethylvaleronitrile Phosphine Potassium persulfate Sodium persulfate Succinic acid peroxide... 

Objections have been raised to the use of AIBN because wasted radicals can give rise to a toxic product, namely tetramethylsuccinodinitrile. For this reason, increasing attention is being paid to the azoester dimethyl 2,2 -azobis-isobutyrate (AZE), Me2 C(COOMe) N N C (COOMe) Me2 which dissociates at 60°C at about the same rate as AIBN. The first reports on applications of [ C]AZE have been published [4,5]. 

The propagating radical of dialkyl itaconate in the homogeneous polymerization was foimd by Sato et al. to be stable enough to be observed by ESR even above 60 °C. Fig. 62 a displays the 5-line spectra obtained when dimethyl 2,2 -azobis-isobutyrate, benzoylperoxide, and di-tert-butylperoxide were used as initiators. On the other hand, the polymerization of DBI initiated with azonitriles such as 2,2 -azobisisobutyronitrile, 2,2 -azobis(2,4-dimethylvaleronitrile), and cyclohexanecarbo-... 

Isotopic enhancement may be also illustrated by Bevington et al. s exploration of the use of the C-enriched free radical initiators 1,1 -azobis(phenylethane) and AIBN in preparing butadiene polymers [51] and the use of dimethyl 2,2 -azobis(isobutyrate) to initiate the polymerisations of styrene, acrylonitrile, methyl methacrylate and methyl acrylate [52]. The signals from the ends are thus rendered more intense, and b ome observable in a standard NMR spectrum, where they display information on the manner in which the initiator radicals have attacked the first monomer to become incorporated at the start of the polymer chain one can thus compare initial and mean tacticities. In a further use of isotope enrichment, Moad and Willing found that selective enrichment... 

Scheme 21 Synthesis of a ABA-tnblock copolymer by successive living radical and living cationic polymerization reaction starting from a bifunctional CTA Te-14. V-601 refers to dimethyl 2,2 -azobis(2-methylpropionate).

Sato, T., Arima, Y, Seno, M., Hirano, T Initiator-fragment incorporation radical polymerization of divinyl adipate with dimethyl 2,2 -azobis(isobutyrate) kinetics and formation of soluble hyperbranched polymer. Macromolecules 38(5), 1627-1632 (2005)... 

Paulsen and his coworkers first synthesized (-f-)-203 from L-quebrachitol (286) by a 21-step reaction as follows. The di-O-isopropylidene derivative was oxidized to the ketone (287), and then epoxidized with dimethyl sulfox-onium-methylide to give 288, which was subjected to benzoylation, mesyla-tion, and demethylation, followed by benzylation, to afford 289. Introduction of unsaturation was accomplished by epoxidation of 289 with sodium methoxide to 290 and 291, and deoxygenation to 292. The azido group was introduced with azobis(dicarboxylate) to give 293, which was hydrogeno-lyzed, followed by deprotection to afford 203. 

The most popular thermal initiator is 2, 2 -azobisisobutyronitrile (AIBN), with a half-life (ti/2) of 1 h at 81 °C and 10 h at 65 °C in toluene [8,21]. Generally, 5-10 mol% of initiator is added either all in one portion or by slow addition over a period of time. There are other azo compounds which can be chosen, depending on the reaction conditions. Indeed, the nature of the substituent play an important role as can be seen for 2, 2 -azobis-(4-methoxy)-3,4-dimethyl-valeronitrile (AMVN), with a ti/2 of 1 h at 56 °C and 10 h at 33 °C in toluene. There are also hydrophilic azo compounds, such as 2, 2 -azobis-(2-methylpropionamidine) dihydrochloride (APPH), with a ti/2 of 10 h at 56 °C in water. 

Diorganyl tellurides add to alkynes via a radical mechanism in the presence of a catalytic amount of a radical initiator such as AIBN or 2,2 -azobis(4-methoxy-2,4-dimethyl-valeronitrile) (In), as well as under irradiation by visible light (tungsten lamp), affording vinylic tellurides in a variable ZIE ratio." ... 

Commonly used catalysts are 2,2 -azobisisobutyronitrile, or organic peroxides. 2,2 -Azobis(4-methoxy-2,4-dimethyl valeronitrile) is the most preferred catalyst (7). 

Azobi -(4-methyl) furazan (called 4.41 Dimethyl-L3-3 -azo-1.2.5-oxdiazol or 4.4 -Dimethyl-3.31-azofurazan in Ger),... 

Azobis methylformate) or Azobisformic Acid, Dimethyl ester, H3COO-N N-COOCHj, mp 122.08, N 22.95% orn-yel oil, bp 96° at 25 mm explodes on rapid heating. It can be prepd by treating the dimethylester of hydrazo-dicarboxylic acid with fuming nitric acid Refs i)Beil 3, (58) [97-8] 2)0.Diels ... 

Matsugi, M. et al. Highly Stereoselective Synthesis of Carbocycles via a Radical Addition Reaction Using 2,2 -Azobis(2,4-dimethyl-4-methoxyvaleronitrile) [V-70LJ. 2.1 1999 [149]... 

Ac, acetyl AIBN, azobis(isobutanonitrile) All, allyl AR, aryl Bn, benzyl f-BOC, ferf-butoxycarbonyl Bu, Butyl Bz, benzoyl CAN, ceric ammonium nitrate Cbz, benzyloxycarbonyl m-CPBA, m-chloroperoxybenzoic acid DAST, diethylaminosulfur trifluoride DBU, l,8-diazabicyclo[5.4.0]undec-7-ene DCC, /V. /V - d i eye I oh e x y I c ar bo -diimide DCM, dichloromethyl DCMME, dichloromethyl methyl ether DDQ, 2,3-dichloro-5,6-dicyano-l,4-benzoquinone DEAD, diethyl azodicarboxylate l-(+)-DET, L-(+)-diethyl tartrate l-DIPT, L-diisopropyl tartrate d-DIPT, D-diisopropyl tartrate DMAP, 4-dimethylaminopyridine DME, 1,2-dimethoxyethane DMF, /V./V-dimethylformamide DMP, 2,2-dimethoxypropane Et, ethyl Im, imidazole KHMDS, potassium hexamethyldisilazane Me, methyl Me2SO, dimethyl sulfoxide MOM, methoxymethyl MOMC1, methoxymethyl chloride Ms, methylsulfonyl MS, molecular sieves NBS, N-bromosuccinimide NIS, /V-iodosuccinimide NMO, /V-methylmorpho-line N-oxide PCC, pyridinium chlorochromate Ph, phenyl PMB, / -methoxvbenzyl PPTs, pyridiniump-toluenesulfonate i-Pr, isopropyl Py, pyridine rt, room temperature TBAF, tetrabutylammonium fluoride TBS, ferf-butyl dimethylsilyl TBDMSC1, f-butylchlorodimethylsilane Tf, trifhioromethylsulfonyl Tf20, trifluoromethylsulfonic anhydride TFA, trifluoroacetic acid THF, tetrahydrofuran TMS, trimethylsilyl TPAP, tetra-n-propylammonium perruthenate / -TsOH. / -toluenesulfonic acid... 

A container was charged with a solution of Vazo 52 catalyst and 2,2 -azobis(2,4-dimethyl pentane nitrile) (4.5 g) dissolved in acetone (600 g) a second container was charged with methyl methacrylate (540 g) and 2-hydroxy ethyl methacrylate (180 g). The first and second containers were uniformly fed into a reactor for 330 and 240 minutes, respectively, and then refluxed for 1 hour. After standard workup the product was isolated in 100% yield, having aMn of 30,308 daltons, Mw of93,195 daltons, and a PDI of 3.07. 

Ethenyl acetate (vinyl acetate, Vac) is polymerizable only by radical species. Until recently, the polymerization of any monomer was out of control because of the unavoidable occurrence of irreversible termination reactions. In 1995, Matyjaszewski and Sawamoto and coworkers reported that the deleterious impact of these irreversible reactions could be minimized by acting on the kinetics of both the propagation and the termination reactions. Indeed, a decrease in the instantaneous concentration of radicals ([M ]) decreases much more importantly the termination rate (proportional to [M ] ) than the propagation rate (proportional to [M ]). A scheme proposed consists in converting reversibly radicals into unstable covalent species ( dormant species). The last radically polymerizable monomer to fall under this type of kinetic control was vinyl acetate. Indeed, very recently Debuigne and coworkers proposed to polymerize Vac by 2.2 -azobis-(4-methoxy-2,4-dimethyl)valeronitrile (V-70) in the presence of cobalt(II) acetyl acetonate [Co(acac)2]. Under these conditions, a linear relationship is observed between... 

Abbreviations acac. Acetyl acetonate AIBN, 2,2-azobis(isobutyro) nitrile bae, dianion of A,iV -ethylenebis(acetylacetoneimine) bdhc, 1,19-dimethyl-AD-bisdehydrocorrinato bdm 1,3 pn, bis(l,3-diacetylmonoximeimino)propane bipy, bipyridyl Bz, Benzyl CIDNP, chemically induced dynamic nuclear polarization cod, cyclooctadienyl COD, cyclooctadiene Cp, Cp, ij-CsMes CT, charge transfer diphos, P(Ph)2CH2CH2P(Ph)2 dmgH,... 

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