Xylenes derivatives

Side-Chain Chlorinated Xylene Derivatives Only a few of the nine side-chaia chlotinated derivatives of each of the xylenes are available from direct chlorination. All three of the monochlotinated compounds, a-chloro-o-xylene (l-(chloromethyl)-2-meth5lbenzene [552-45-4] a-chloro-y -xylene (1-(ch1oromethy1)-3-methylhenzene [620-19-9] a-chloro-/)-xylene (1-(ch1oromethy1)-4-methylhenzene [104-82-5]) are obtained ia high yield from partial chlorination of the xyleaes. 1,3-Bis(ch1oromethy1)henzene [626-16-4] can be isolated ia moderate yield from chlorination mixtures (78,79). 

In 1975, Weber and Vogtle showed that open-chained polyethers, 2,6-pyridine-dimethanol, and ortho-xylene derivatives terminated in an 8-quinolinyl group could form stable, 1 1, crystalline complexes with a variety of metal salts. The podands were prepared from 8-hydroxyquinoline and the corresponding dihalides. A typical example is shown in Eq. (7.10). 

Polyester is the Madison Avenue name for PET, polyethylene terephtha-late. Be careful, though, because PET is not a polyethylene-type chemical— its a xylene derivative. If you remember that esters usually end in -ate and are based on the acid from which they are derived, then you can see that the ester in polyester is ethylene terephthalate. 

Behechti, A., Schramm, K.-W., Attar, A., Niederfellner, J. and Kettrup, A. (1998) Acute aquatic toxidties of four musk xylene derivatives on Daphnia magna. Water Res., 32 (5), 1704—1707. 

The formation of a,a -dihalo- >-xylenes as intermediates in the polymerization has been demonstrated, when the electrolysis was conducted at low temperature, as —10° C, and at —0.70 V of the cathode potential in a solution of tetrahydrofuran using a lead or mercury cathode. The polymerization of xylylenes took place immediately above room temperature. Only poly-2-chloro-/>-xylylene prepared from a,a -debromo-2-chloro -xylene and a,a -2-trichloro-/>-xylene were soluble of six polymers of xylene derivatives, and the reduced viscosity of an 0.2 percent solution in chloronaphthalene at 170° C was 0.68 to 0.78. This compared with a reduced viscosity of 0.65 of the same polymer prepared by the reaction of a,a -2-dichloro-/>-xylene with potassium butoxide. 

Anodic oxidation of a, a -bis(trimethylsilyl)xylenes in alcohols provides the corresponding monoalkoxylated products solely. Among a, a -bis(trimethylsilyl)-o-, -m- and -p-xylenes, the p-xylene derivative gave the best yields of alkoxylated products as shown in equation 810. 

Due to a relatively high content of the m- isomer xylene derived from coal or xylene from Borneo oil is the most convenient starting material for the preparation of nitration grade xylene. 

The preparation of this class of dienes has received considerable attention during the last few years. Scheme 127 depicts the current approaches, such as 1,4-eliminations of o-xylene derivatives via reduction (544) - (M2), thermal dehydrohalogenation ( 5) (542), and fluoride-induced desilylation... 

With substituted cycloproparenes, the regioselectivity of the silver(l)-catalyzed and the uncatalyzed reaction was markedly different. Thus, 2-methylbenzocyclopropene (2) reacted with hydrochloric acid to give predominantly w-xylene 3a (47%), but reacted with silver(I) nitrate in the presence of ethanol or aniline to give preferentially o-xylene derivatives 4b,c. 3-Methyl-benzocyclopropene (5a) gave predominantly the w-xylene 7a with hydrochloric acid, but p-xylenes 6b,c in the silver(I)-catalyzed reaction. 3-Chlorobenzocyclopropene (5b) underwent addition of hydrochloric acid to give a mixture of 3- and 4-chlorobenzyl chlorides 6d and 7d, ° but silver(I)-catalyzed methanolysis gave only the 4-chlorobenzyl ether 7e. ... 

World Tables, p-xylene Derivatives World Supply Demand Report, 2002 52. 

Halogen-substituted xylenes can also be ammoxidized 3,4,5,6,-tetrachloro-phthalodinitrile is formed from the corresponding o-xylene derivative (45 % yield) [80]. 

Chart I shows the structures of the bis(halomethyl) aromatics 18 -- 26 that we have used in our studies. These compounds were commercially available or were prepared by the reaction of N-bromosuccinimide with the corresponding o-xylene derivatives. 

In Fig. 8, a set of uptake curves for ethylbenzene adsorbed and desorbed at various temperatures after various partial pressure changes has already been shown. The diffusivities of benzene and p-xylene derived from IR measurements in the same way as described for ethylbenzene are collected in Tables 3 and 4. Table 3 includes data for single-component diffusion as well as for co-and counter-diffusion (see Sect. 2.2.4.1)... 

Scheme 10.4 Proposed decomposition path of a xylene-derived phosphine-based pincer complexes in the presence of triethylamine.

High reaction temperatures were found to be crucial for their irreversible decomposition into nanoparticles, because recent investigations on xylene-derived... 

Finally, it should be mentioned that two years later, an enantioselective oxidative (boron) Heck-type reaction was reported by Jung and coworkers [32] for a dinuclear NHC-derived CNO-based pincer complex for which for the first time a Pd /Pd" mechanism was suggested to be operative with palladium pincer-type crosscoupling catalysts. Reaction mechanisms without a change of the palladium s oxidation state have never been proposed to be operative for Heck cross-couphng reactions, but have been shown to be operative for xylene-derived selenium-based pincer complexes and related systems in the cross-couphng of vinyl epoxides (and aziridines) with organoboronic acids [24d, 33]. 

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