Halogen treatment

Aniline is readily halogenated, treatment with bromine water giving an instant precipitate of 2,4,6-tribromoaniline. 

A derivative of an isomeric azapurine ring system interestingly exhibits bronchodilator activity, possibly indicating interaction with a target for theophylline. The starting pyridazine 97 is available from dichloro compound 96 by sequential replacement of the halogens. Treatment of 97 with formic acid supplies the missing carbon and cyclizes the intermediate formamide with consequent formation of zindotrine (98) [16]. 

Cepeda-Jimenez C.M., Pastor-Bias M.M., Martln-Martfnez J.M., and Gottschalk P., 2003, Treatment of thermoplastic rubber with bleach as an alternative halogenation treatment in the footwear industry, J. Adhes., 79(3), 207-237. 

Pastor-Bias M.M. and Martm-Martmez J.M., 2002, Different surface modifications produced by oxygen plasma and halogenation treatments on a vulcanised rubber, J. Adhes. Sci. Technol., 16(4), 409 28. 

Sokol skaya, El piner IE (1957) The halogen treatments of coals under the action of ultrasonic waves. Dokl Akad Nauk SSSR 114(2) 372-374... 

It is possible to effect reduction of tertiary benzylic hydroxy functions in the presence of primary halogens. Treatment of 1,1-diphenyl-l-hydroxy-2-haloethanes in chloroform with a slight excess of triethylsilane and a 9- to 10-fold excess of trifluoroacetic acid yields the corresponding 2,2-diphenyl-1-haloethanes (Eq. 45). The yield of the chloride is 77% after one hour at —15°, whereas that of the bromide is 66% following one hour at 0°.184... 

Morita, M., Shigematsu, M. and Sakata, I. (1987). An improvement of the thermoplasticity and the solvent-solubility of cyanoethylated wood by halogen treatment. Cellulose Chemistry and Technology, 21(3), 255-265. 

A reaction, that does not involve the enediol takes place on halogenation. Treatment of 138 with hydrogen bromide-acetic acid affords 5-0-acetyl-6-bromo-6-deoxy-L-ascorbic acid (166).360 Compound 166 was used for the synthesis of 6-substituted derivatives of 138, via the 5,6-anhydro derivative.361... 

The first substitution reaction we examine is halogenation. Treatment of a ketone or aldehyde with halogen and either acid or base results in substitution of X for H on the a carbon, forming an a-halo aldehyde or ketone. Halogenation readily occurs with CI2, Br2, and I2. 

Cleavage with formation of the halide is accomplished with a number of reagents other than the halogens. Treatment of hexamethylditin with hydrobromic (206) or hydrochloric (273) acid leads to the corresponding trimethyltin halide. In contrast, hexaethylditin has been found to react with 4 moles of hydrogen chloride to form diethyltin dichloride. 

Nuclear graphite is usually manufactured from high-grade coke filler and pitch binder, processed as described earlier in this chapter, and then thoroughly purified by halogen treatment (see Sec. 2.3 above). The highest degree of purity is necessary to attain the required nuclear properties. 

Ellul [27] subjected EPDM/polypropylene and natural rubber/polypropylene blends to various halogenation treatments, namely fluorine/carbon dioxide, sodium hypochlorite/ acetic acid and bromine water. With the natural rubber blend, there was a substantial uptake of fluorine, chlorine and bromine in the surface regions as indicated by energy dispersive X-ray analysis and with all three pre-treatments the adhesion to an acrylic tape was greatly enhanced. In contrast, with the EPDM blend, fluorine was the only reagent which reacted with the rubbers and only this treatment resulted in a significant increase in adhesion to the acrylic tape. The above results can be explained in terms of the different concentrations of carbon-carbon double bonds in the two blends. Substantial incorporation of chlorine and bromine could occur with the natural rubber-polypropylene blend but not with the EPDM blend. However, fluorine gas will react readily with saturated hydrocarbons [28,29] and therefore the incorporation of fluorine into the EPDM blend is not surprising. 

FIGURE 11.1 Schematic of the apparatus used in the synthesis of CDC through the halogen treatment of metal carbides. 

Impact of CDC Precursor, Electrolyte (AC, Acetonitrile PC, Propylene Carbonate), and Halogen Treatment Temperature (among Various Other Parameters) on Pore Structure and Specific Capacitance... 

Chemical Dehydroxylation describes methods based on chemical reactions such as halogen treatments. 

Scheme for preparing optically clear, bubble-free, and OH-free silica glass employing a halogen treatment followed by annealing in oxygen and sintering in He [52],... 

---