Azobisisobutyronitrile preparation

A) The preparation of [H-chloroethoxyjchloromethyl]phosphonic acid Acetaldehyde (1.1 mol) and hydroxymethylphosphonlc acid (1 mol) in 500 ml of benzene are saturated with hydrogen chloride gas at 10°C to 15°C. The mixture is aged at 25°C for 24 hr, the solvent distilled out in vacuo and the residue flushed three times with benzene to remove all traces of hydrogen chloride. The residue is taken up in benzene (500 ml), treated with tert-butyl hypochlorite (0.8 mol) and azobisisobutyronitrile (0.8 mm) at 40°C until titration shows the absence of hypochlorite and the solution is then evaporated to yield [(1-chloro-ethoxy)chloromethyll phosphonic acid in the form of an oil. 

Konig et al. have achieved thioether functionalization of T8[CH = CH2]8 via the radical addition of thiols such as thiophenol, cyclohexylthiol, and 2-mercaptopyridine in the presence of azobisisobutyronitrile (AIBN) as a radical initiator (Table 13), while Gao et al. have also used this method to prepare very highly functionalized POSS by reacting T8[CH = CH2]8 with thiol-terminated glycosides giving glycoclusters in 70% yield (Figure 22). 

PVPA was prepared by the free-radical homopolymerization of vinyl-phosphonyl dichloride using azobisisobutyronitrile as initiator in a chlorinated solvent. The poly(vinylphosphonyl chloride) formed was then hydrolysed to PVPA (Ellis, 1989). No values are available for the apparent pA s of PVPA, but unpolymerized dibasic phosphonic acids have and values similar to those of orthophosphoric acid, i.e. 2 and 8 (Van Wazer, 1958). They are thus stronger acids than acrylic acid, which as a pK of 4-25, and it is to be expected that PVPA will be a stronger and more reactive acid than poly(acrylic acid). 

Polymer extracts are frequently examined using GC-MS. Pierre and van Bree [257] have identified nonylphenol from the antioxidant TNPP, a hindered bisphenol antioxidant, the plasticiser DOP, and two peroxide catalyst residues (cumol and 2-phenyl-2-propanol) from an ABS terpolymer extract. Tetramethylsuccino-dinitrile (TMSDN) has been determined quantitatively using specific-ion GC-MS in extracts of polymers prepared using azobisisobutyronitrile TMSDN is highly volatile. Peroxides (e.g. benzoyl or lauroylperoxide) produce acids as residues which may be detected by MS by methylation of the evaporated extract prior to GC-MS examination [258]. GC-MS techniques are... 

An alternative method of preparing the saturated cyclic amines via cyclopolymerization of diallylamine or diallylammonium chloride was unsuccessful. Common free radical initiators such as 2,2 -azobisisobutyronitrile, ammonium persulfate, benzoyl peroxide were found to be ineffective. Several procedures reported in the literature were followed, and unfortunately all of them have resulted only a small amount of low molecular weight oligomers. Further research for polymerization conditions and types of initiation is still required. 

Radical polymerizations of vinyl-substituted ultraviolet stabilizers were accomplished with azobisisobutyronitrile (AIBN) as initiator, with careful exclusion of oxygen. Copolymerization was also readily achieved. The following sections describe in detail the preparation of polymeric ultraviolet stabilizers from salicylate esters, 2-hydroxybenzophenones, a-cyano-p-phenyl-cinnamates and hydroxyphenylbenzotriazoles. 

Poly(styrene) and PMMA were synthesized from their respective monomers using azobisisobutyronitrile-initiated radical polymerization in benzene. Four freeze-pump-thaw cycles were used to degas the monomer solutions and polymerization was carried out for 48 hours at 60°C. The polymers were purified by multiple reprecipitations from dichloromethane into methanol. Films of these polymers were prepared and found to be free of any fluorescent impurity. 

The silylated tin compound 199, obtained from tributyltin hydride and N-bis(trimethylsilyl)propargylamine (198) in the presence of a trace of AIBN (2,2/-azobisisobutyronitrile), is a versatile reagent for the preparation of allylic amines. Treatment with aryl bromides ArBr (Ar = Ph, 4-MeOCgH4, 4-O2NC6H4 etc.) under Pd(PPh3)4 catalysis yields the silylated amines 200, which are hydrolysed by acids to the free amines 201. 199 is converted into the lithium compound 202, which is transformed into 203 by aqueous ammonium chloride and into 204 by the action of alkyl halides RX (R = Me, Et or allyl) (equation 76)204. 

A general method for the generation of aminyl radicals is by treatment of sulphenamides 340, prepared from secondary amines and A-benzenesulphenylphthalimide, with tributyltin hydride in the presence of AIBN (2,2/-azobisisobutyronitrile). The cyclopropyl derivative... 

To make further use of the azo-initiator, tethered diblock copolymers were prepared using reversible addition fragmentation transfer (RAFT) polymerization. Baum and co-workers [51] were able to make PS diblock copolymer brushes with either PMMA or poly(dimethylacrylamide) (PDMA) from a surface immobihzed azo-initiator in the presence of 2-phenylprop-2-yl dithiobenzoate as a chain transfer agent (Scheme 3). The properties of the diblock copolymer brushes produced can be seen in Table 1. The addition of a free initiator, 2,2 -azobisisobutyronitrile (AIBN), was required in order to obtain a controlled polymerization and resulted in the formation of free polymer chains in solution. 

In a similar way, polymeric azo initiators have been prepared by desactivation of a living anionic polymer with functionalized azo derivatives as azobisisobutyronitrile ( , 12). Concerning this reaction with azobisisobutyronitrile (AIBN), no details on the methanism have been given in the patent litterature. 

Materials. Polymer-bonded sensitizers and their model compounds are shown in Figure 2. Samples 1-5 were prepared by radical copolymerization of corresponding ethylenic monomers using azobisisobutyronitrile as initiator at 70°C in DMF(5) or DMF/H20 (9/1 for 1, 2 and 4 8/1 for 3) (15). Sample 7 was prepared by the same procedure as 6 (16). The copolymer compositions... 

Polymerization. Poly (methyl methacrylate) was obtained commercially. The polymers of other methacrylates and their copolymers were prepared in toluene with 2,2 -azobisisobutyronitrile (AIBN) at 60 °C. All the polymers prepared free radically were syndiotactic or atactic. Isotactic poly(a,a-dimethylbenzyl methacrylate) was obtained using C6H5MgBr as the initiator in toluene at 0°C. Poly(methacrylic acid) was prepared in water using potassium persulfate at as the initiator 60 °C. The molecular weights, glass transition temperatures and tacticities of the polymethacrylates are summarized in Table I. 

A 0.056-g sample of AIBN (2,2 -azobisisobutyronitrile) is placed into a one-piece 100-mL flask (such as Chemglass AF-0522-02)t equipped with a Teflon vacuum stopcock and a magnetic stir bar, and the flask is evacuated at — 196°C. A 1.69-g (15.9 mmol) sample of B-vinylborazine (prepared by the procedure described above) is vacuum distilled into the flask. Three freeze-pump-thaw cycles are performed in order to remove any traces of oxygen. The stopcock is closed and the reaction flask is removed to a shielded hood where it is heated in an oil bath at 70°C for about 3 h, at which point the material is sufficiently viscous that the stir bar stops. Then 5 mL of benzene is condensed into the flask and the solution is heated at 70°C for another 9 h. Slow addition of the benzene solution into 40 mL of pentane under inert atmosphere affords the precipitation of 0.73 g (43.2% yield) of poly(B-vinyl-borazine). The polymer is filtered under nitrogen and dried in vacuo for about 5 min. 

Polycarbophil. Polycarbophil [73038-24-1] (copolymer of acrylic acid and divinyl glycol (l,5-hexadiene-3,4-diol [1069-23-4])) consists of white-to-creamy white granules having a slight ester-like odor. It swells to contain a maximum of 1.5% water, but is insoluble in water and most organic solvents. It is prepared by copolymerization of acrylic acid and divinyl glycerol in a hot salt slurry using azobisisobutyronitrile as the initiator. 

Azobisisobutyronitrile (Formula 496) undergoes rearrangement to the ketenimine (Formula 497) on irradiation in benzene (225). This is the choice method of preparation of Formula 497 (225). 

MMA macromers were prepared by using a cobalt chain-transfer catalyst (CoCTC) and azobisisobutyronitrile (AIBN) as the... 

Pancratistatln. The first total synthesis of ( )-pancratistatin (94) (Scheme 14), the structurally most complex of narciclasine alkaloids, was achieved by Danishefsky [27]. The requisite starting material, the substituted benzaldehyde 95 prepared from pyrogallol in six steps in 18% overall yield, was converted via the homoallylic alcohol 96 into the diene 97. Reaction of 97 with 2-nitrovinylsulphone yielded the cycloadduct 98, which on treatment with tributyltinhydride and 2,2 -azobisisobutyronitrile furnished the cyclohexadiene 99. Whilst the cyclisation of the silylether 99 or the derived phenol, under the influence of iodine, could not be accomplished, the more nucleophilic stannylether did participate in the desired ring closure and provided via the iminium salt, the iodolactone 100 on aqueous work-up. 

Horvath s group has recently reported the preparation of porous rigid monolithic capillary columns for CEC by polymerizing mixtures of chloromethylstyrene 21, divinylbenzene 22 and azobisisobutyronitrile in the presence of various porogenic solvents such as methanol, ethanol, propanol, toluene, and formamide [49]. The capillary wall was silanized using a 50% dimethylformamide solution of 3-(trimethoxysilyl)propyl methacrylate 8 at a temperature of 120°C for 6 hours. In order to avoid the spontaneous polymerization of the functional methacrylate, a stable free radical (DPPH) was added to the solution. The SEM micrographs of Fig. 6.16... 

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