Friedel-Crafts reaction copolymers

Another type of soHd supetacid is based on perfluorinated resin sulfonic acid such as the acid form of Du Font s Nafion resin, a copolymer of a perfluorinated epoxide and vinylsulfonic acid or soHd, high molecular weight petfluotoalkanesulfonic acids such as petfluotodecanesulfonic acid, CF2(CF2)qS02H. Such sohd catalysts have been found efficient in many alkylations of aromatic hydrocarbons (225) and other Friedel-Crafts reactions (226). 

Chloromethylation. A Friedel-Crafts reaction between the copolymer and chloromethoxymethane with aluminium chloride as the catalyst introduces chloromethyl groups (—CH2CI) into the ethenylbenzene nuclei. What appears to be a simple step is in fact a critical stage in the synthesis, demanding strict techniques to firstly minimize undesir-... 

The generation of homo- and copolymers prepared by Friedel-Crafts reactions of 2,7-bis [(2-ferroceneyl)methylene]cycloheptanone with various diacid chlorides has been reported.222 These polyketones were insoluble in most common organic solvents, but were quite soluble in concentrated H2S04. The homopolymers were thermally stable with two decompositions between 220 and 520°C, and the copolyketones showed decomposition at temperatures between 250 and 600°C. In both cases the first weight loss was determined to depend on the nature of the polymers and occurred at a faster rate than the second degradation. 

M. Negre, M. Bartholin and A. Guyot, Autocross-linked isoporous polystyrene resins, Angew. Makromol. Chem., 1979, 80, 19-30 J. Hradil and E. Kralova, Styrene-divinylbenzene copolymers post-cross-linked with tetrachloromethane, Polym., 1998, 39, 6041-6048 S. Belfer and R. Glozman, Anion exchange resins prepared from polystyrene cross-linked via a Friedel-Craft reaction, J. Appl. Polym. Sci., 1979, 24, 2147-2157. 

Ando et al. [62, 63] suggested using unreacted double bonds in swollen styrene-DVB copolymers, which also react with aromatic rings via Friedel-Crafts reaction forming rigid crosslinks ... 

Spectrum. On the other hand, this band is revealed in the spectrum of the styrene-0.6% DVB copolymer intensively crosslinked with 1 mol of MODE, which contains a comparable amount (1%) of pending chlorine. It is quite possible that industrial MN-200 contains chlorine of a different kind. A part of rather inert chlorine in the form of chloroethyl groups may have originated by the involvement of EDO into the Friedel—Crafts reaction. One may also assume that the initial copolymer of that product incorporates more DVB thus the unreacted pendent double bonds may have interacted with MCDE during the post-crosslinking reaction, leading to the formation of methyl chloropropyl ether fragments [105] ... 

Other types of hypercrosslinked sorbents, namely commercial Lewatit EP63, laboratory samples obtained by post-crosslinking styrene-DVB copolymer with CCI4 [55], by self-crosslinking macroporous copolymer of vinylbenzyl chloride with 20% DVB via Friedel-Crafts reaction [56], or by bridging preliminary chloromethylated macroporous styrene-DVB copolymer [57, 58], are all superior to XAD-2, XAD-4, and activated carbon Ambersorb XE340 with respect to phenol and nitrophenol removal. Material [20%-VBC(F.C.)] retains 2,4-dichlorophenol much stronger than unsubstituted phenol, and, therefore, the presence of phenol in the solution does not impact the retention of the chlorinated phenol. On the contrary, the sorption of phenol from the binary solution depends heavily on the concentration of 2,4-dichlorophenol. 

Stannic chloride is a very effective catalyst for this Friedel-Craft reaction [186]. lodomethylation can also be carried out in the same manner with similar results [179]. When the reactions are carried out on cross-linked styrene copolymers with chlorodimethyl ether and stannic chloride catalyst, they are accompanied by strong morphological changes [187]. If these reactions are carried out with low levels of chloromethylating agents or catalysts, they occur more or less homogeneously. Larger levels... 

Havens and Reimer have used carbon-13 NMR measurements to study the sequence distribution in a series of aryl ether ketone copolymers [41]. These copolymers were based on terephthaloyl chloride (T), 1,4-diphenoxy-benzene (B), and diphenyl ether (E) and were prepared by a Friedel-Crafts reaction using either HF/BF3 or buffered AICI3 as the catalyst. The copolymers formed are comprised of T units alternating with either E or B units. 

Traditionally, anion-exchange resins have been made by a two-stage set of reactions (although other synthesis methods are now being used). The first step is a Friedel-Crafts reaction to attach the chloromethyl group to the benzene rings of styrene-divinylbenzene copolymer. Then the anion exchanger is formed by reaction of the chloromethylated resin with an amine. The most common type of... 

Similarly, synthetic rubber was vital to the ground-war effort in World War II, after the Japanese cut off the Allies from sources of natural rubber in Southeast Asia (see Historical Highlight in Chapter 11). A synthetic rubber was developed in an amazingly short time in a remarkable display of cooperation between government officials and industrial and academic scientists. This rubber was a copolymer (Sec. 22.1) that contained styrene as a key component. Styrene is made from ethylbenzene, which is prepared industrially by the Friedel-Crafts reaction of benzene and ethylene, as shown below. 

The side fuUerenation of poly(epoxypropylcarbazole) (PEPC) 57 has been achieved by grafting Ca) via a Friedel-Crafts reaction (Figure 2.5) [56]. Analogously, the same synthetic strategy applied to polyvinylcarbazole (PVK) led to chemically modified PVK copolymer, in which, after laser flash photolysis, photoinduced electron transfer between and inter- and intrachain carbazole units takes place (polymer 58 - Figure 2.5) [57]. Kang and coworkers have exploited this behavior... 

Sometimes, ion-exchanging groups are introduced on to the resins and these are synthesized by first preparing the styrene-divinyl benzene copolymer [as in Eq. (1.7.1)] in the form of beads, and then the chloromethylation is carried out. Chloromethylation is a Friedel-Crafts reaction catalyzed by anhydrous aluminum, zinc, or stannous chloride the polymer beads must be fully swollen in dry chloromethyl methyl ether before adding the catalyst, ZnCla. Normally, the resin has very small internal surface area and the reaction depend heavily on the degree of swelling. This is a solid-liquid reaction and the formed product can be shown to be... 

Since initiation with conventional Friedel-Crafts halides cannot be controlled, the fine-tuning of reactions becomes extremely cumbersome. In contrast, by the use of alkylaluminum compounds elementary events (initiation, termination, transfer) become controllable and thus molecular engineering becomes possible. Indeed, by elucidating the mechanism of initiation etc., a large variety of new materials, i.e., block3, graft4-6 bigraft7 copolymers, have been synthesized and some of their physical-chemical properties determined. 

Weak Base Anion Exchangers. Both styrenic and acrylic copolymers can be converted to weak base anion-exchange resins, but different synthetic routes are necessary. Styrene—DVB copolymers are chloromethylated and aminated in a two-step process. Chloromethyl groups are attached to the aromatic rings (5) by reaction of chloromethyl methyl ether [107-30-2], CH3OCH2Cl, with the copolymer in the presence of a Friedel-Crafts catalyst such as aluminum chloride [7446-70-0], A1C13, iron(III) chloride [7705-08-0]9 FeCl3, or zinc chloride [7646-85-7], ZnC. ... 

As films are used e.g. the polymerization product of ethylbenzene and divinylbenzene (33) the copolymer of styrene and butadiene (755) the copolymer of styrene and butadiene mixed with polyethylene (157) a vulcanized or cyclized copolymer of an aromatic vinylcompound and an aliphatic conjugated polyene (2). As a crack resisting matrix is mentioned the copolymer of styrene, divinylbenzene and butadiene with e.g. dioctylphthalate as a plasticizer (176). Other examples are the copolymers of unsaturated aromatic compounds and unsaturated aliphatic compounds (77) and the reaction products of polyolefines and partially polymerized styrene (174). Primary groups can be introduced also with the help of Friedel-Crafts catalyst. Ts. Kuwata and co-workers treated a film of a copolymer of styrene and butadiene with an aluminium-ether complex and ethylenedichloride (79). Afterwards they allowed the film to react with trimethylamine. Another technique is the grafting of e.g. a polyethylene film with styrene (28). 

Scherf and Mullen prepared (Scheme 47) the ladder-type polyphenylene (LPPP, 5) with methine bridges [126-129], via a poly(diacylphenylene-co-phenylene) precursor copolymer 103 obtained by an AA-BB type Suzuki polycondensation. The key step is the polymer analogous Friedel-Crafts ringclosing reaction on the polyalcohol 104, obtained by the reduction of 103. This was found to proceed quickly and smoothly upon addition of boron-trifluoride to a solution of 104 in dichloromethane. The reaction appeared to be complete by both NMR and MALDI-TOF analysis, indicating the presence of less than 1% of defects due to incomplete ring closure. LPPPs with num-... 

Fullerene-styrene copolymers have been prepared in radical initiated and thermal polymerization reactions [148-151]. In radical copolymerizations of Cgg and styrene, copolymers with Cgg contents up to 50% (wt/wt) can be obtained [150]. Electronic absorption spectra of the copolymers are very different from that of monomeric C o (Fig. 36). The absorptivities per unit weight concentration of the copolymers j increase with increasing C q contents in the copolymers in a nearly linear relationship (Fig. 37). Fluorescence spectra of the Cgg-styrene copolymers, blue-shifted from the spectrum of monomeric Cgo, are dependent on excitation wavelengths in a systematic fashion [149]. Interestingly, the observed absorption and fluorescence spectral profiles of CgQ-styrene and Cyg-styrene copolymers are very similar, even though the spectra of monomeric CgQ and C70 are very different. The absorption and fluorescence spectra of the fullerene-styrene copolymers are also similar to those of the pendant Cgg-poly-styrene polymer (19) prepared in a Friedel-Crafts type reaction [150,156]. 

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