Benzyl chloride polymerization

Substituted aroyl- and heteroaroyltrimethylsilanes (acylsilanes) are prepared by the coupling of an aroyl chloride with (Me3Si)2 without decarbonylation, and this chemistry is treated in Section 1.2[629], Under certain conditions, aroyl chlorides react with disilanes after decarbonylation. Thus the reaction of aroyl chlorides with disilane via decarbonylation is a good preparative method for aromatic silicon compounds. As an interesting application, trimel-litic anhydride chloride (764) reacts with dichlorotetramethyidisilane to afford 4-chlorodimethylsilylphthalic anhydride (765), which is converted into 766 and used for polymerization[630]. When the reaction is carried out in a non-polar solvent, biphthalic anhydride (767) is formed[631]. Benzylchlorodimethylsilane (768) is obtained by the coupling of benzyl chloride with dichlorotetramethyl-disilane[632,633]. 

Carbon tetrachloride [56-23-5] (tetrachloromethane), CCl, at ordinary temperature and pressure is a heavy, colorless Hquid with a characteristic nonirritant odor it is nonflammable. Carbon tetrachloride contains 92 wt % chlorine. When in contact with a flame or very hot surface, the vapor decomposes to give toxic products, such as phosgene. It is the most toxic of the chloromethanes and the most unstable upon thermal oxidation. The commercial product frequendy contains added stabilizers. Carbon tetrachloride is miscible with many common organic Hquids and is a powerhil solvent for asphalt, benzyl resin (polymerized benzyl chloride), bitumens, chlorinated mbber, ethylceUulose, fats, gums, rosin, and waxes. 

Benzyl chloride reacts with benzene in the presence of a Lewis acid catalyst to give dipbenylmetbane [101 -81-5]. It undergoes self-condensation to form polymeric oils and soHds (21). With phenol, benzyl chloride produces a mixture of o- andp-her zylpbeno1. 

A gas chromatographic determination of benzotrichloride and related compounds ia the work environment, after adsorption on a polymeric adsorbant and desorption with CCl has been reported (61). Trace amounts of benzyl chloride, benzal chloride, and benzotrichloride ia environmental samples can be analyzed by Method 8120 of EPA ManualSW-846 with modifications (62). 

The chloromethylation can be generally employed in aromatic chemistry benzene, naphthaline, anthracene, phenanthrene, biphenyls and many derivatives thereof are appropriate substrates. The benzylic chlorides thus obtained can be further transformed, for example to aromatic aldehydes. Ketones like benzophe-none are not reactive enough. In contrast phenols are so reactive that polymeric products are obtained. ... 

To develop thermal iniferters which act at a lower temperature, Otsu and Tazaki proposed a redox iniferter system [153,154]. For example, reduced nickel (Ni°) reacts with organic halides (R-X) such as benzyl chloride to form a radical, which can initiate polymerization (Eqs. 33-35) ... 

The pyrolysis temperature and the rate of addition are chosen such that about 50% of the acid chloride is recovered as 2-toluic acid after hydrolysis. Under these conditions only a small amount of benzyl chloride and polymeric material is formed in addition to benzocyclobutenone. The percentage of reactant conversion depends not only on the pyrolysis temperature, but also on the pressure in the reactor and on the rate of reactant addition. It is advisable, therefore, to optimize the pyrolysis temperature in trial runs keeping the other variables constant. 

Tellurium tetrachloride, a source of TeClj ions, behaves as a cationic catalyst for oligo-and polymerization reactions. Two types of monomer, phenyl-substituted ethylenes and benzyl chlorides, have been submitted to these reactions. ... 

The termination of polymerization of substituted ethylenes is by an internal Friedel-Crafts reaction, whereas that of the substituted benzyl chlorides is by the reaction with chloride ions. 

The chloromethylated polystyrene is usually obtained by chloromethylation of polystyrene (Eq. 9-38), although polymerization of p-vinyl benzyl chloride has also been used [Arshady et al., 1976]. A less desirable variation of this approach is the physical entrapment of a catalyst, substrate, or reagent within a polymer. 

A convenient method for carrying out the reaction of a high cis-1,4-polybutadiene with PVC was to polymerize butadiene using a suitable catalyst system—e.g., Et2AlCl-cobalt stearate-terf-butyl chloride or Et3Al-cobalt chelate-benzyl chloride, and then to add an appropriate quantity of the resultant polybutadiene solution to a suspension of PVC in chlorobenzene. Additional Et2AlCl could then be added to the reaction mixture, although this was unnecessary if the initial concentration was adequate. 

Frechet and coworkers recently described how living free radical polymerization can be used to make dendrigrafts. Either 2,2,6,6-tetramethylpiperidine oxide (TEMPO) modified polymerization or atom transfer radical polymerization (ATRP) can be used [96] (see Scheme 10). The method requires two alternating steps. In each polymerization step a copolymer is formed that contains some benzyl chloride functionality introduced by copolymerization with a small amount of p-(4-chloromethylbenzyloxymethyl) styrene. This unit is transformed into a TEMPO derivative. The TEMPO derivative initiates the polymerization of the next generation monomer or comonomer mixture. Alternatively, the chloromethyl groups on the polymer initiate an ATRP polymerization in the presence of CulCl or CuICl-4,4T dipyridyl complex. This was shown to be the case for styrene and n-butylmethacrylate. SEC shows clearly the increase in molecu-... 

Initial reports leading to speculation about non-linear or branched polymeric connectivity were provided by researchers such as Zincke,121 who isolated an insoluble hydrocarbon-based material upon the treatment of benzyl chloride with copper. Later, in 1885, reaction of benzyl chloride with aluminium chloride led Friedel and Crafts131 to report similar observations. When benzyl chloride was subjected to the action of a zinc-copper couple analogous materials were obtained.141... 

In Nd alcoholate-catalyzed polymerizations, as a rule of thumb, the same halide donors are applied at the same molar ratios as with Nd-carboxylate-based catalyst systems. In the literature, hydrocarbon soluble as well as hydrocarbon insoluble halide donors are combined with Nd-alcoholates. Examples are benzyl chloride (BzCl) [37,38], AlBr3 [224,225], AlEtCl2 [226,227], Et2AlCl [231], fBuCl [231,232] and Me3SiCl [231]. 

The synthesis of polybenzyls by carbenium ion intermediates has been summarized in several reviews [27,28]. Polybenzyls obtained from the polymerization of benzyl chloride are amorphous, highly branched polymers [29] (Fig. 12). 

One exception to the amorphous structure has been reported [30]. Crystalline polybenzyl was obtained from the low temperature (- 125° C) polymerization of benzyl chloride. However, the reaction was difficult to reproduce [31,32]. Consequently this procedure is not an effective method for the synthesis of linear polybenzyls. The usual amorphous, highly branched structure is formed as a result of a lack of positional selectivity and multiple substitution of the arene rings. Similar polymeric structures are obtained upon the polymerization of other nonsubstituted benzyl halides and benzyl alcohol [29]. The highly branched structure is a consequence of the involvement of benzyl carbenium ions in the Friedel-Crafts reaction. Benzyl substituents activate the monosubstituted phenyl groups toward further benzylation reaction. However, monomers containing alkyl substituents that sterically hinder substitution at the ortho position have been polymerized to linear polybenzyls. For example, the following... 

Figure 12 Example of typical polybenzyl structure obtained by the polymerization of benzyl chloride. (From Ref. 28.)...

A series of polymerizations were performed to determine the effect of changing the diphenyl sulfone central group of the bis(phenoxy) and bis(phenylthio) monomers to a pentanedioxy group. The polymers obtained from methyl-substituted 1,5-bis(phenoxy)pentane contained structural units derived from proton transfer reactions [214]. Thus diphenyl methane, 1,2-diphenyl ethane, and benzyl chloride units were detected (Fig. 52). 

Summary AIBN-type radical polymerization initiators have been grafted onto poly-ciystalline titanium surfaces allowing synthesis of polymer films covalently bound to the surfaces. Vinylic monomers such as styrene, methyl methacrylate, and 4-chloromethyl-styrene have been used the pendant benzyl chloride moiety present at the outer surface of the polymer film obtained fi om the latter monomer has allowed further functionalization of the system. In the case of polystyrene films on Ti, molecular weights of the polymer have been estimated to be A/w == 25 000 A/ = 10 000 (Pd = 2.5). 

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