Reaction with other halogens halogenation

Borides are relatively inert, especially to non-oxidizing reagents. They react violently with fluorine, often with incandescence. Reaction with other halogens is not as violent and may require some heat. Resistance to oxidation, acids, and alkalis is summarized in Table 17.5. In oxidation conditions, a layer of boric oxide is formed on the surface which passivates it to some degree. Boric oxide melts at 450°C and vaporizes at 1860°C. It offers good protection up to 1500°C in a static environments but it has low viscosity at these temperatures and tends to flow under stress and the protection it offers is limited.f k l... 

Thallium burns in fluorine with incandescence. Reactions with other halogens form halides. Thallium combines with several elements forming binary compounds. 

C. Reaction with Other Halogen-Containing Molecules. 261... 

In the last reaction, the pi electrons of an alkene attack the bromine molecule, expelling bromide ion. A bromonium ion results, containing a three-membered ring with a positive charge on the bromine atom. This bromonium ion is similar in structure to the mercurinium ion discussed in Section 8-5. Similar reactions with other halogens form other halonium ions. The structures of a chloronium ion, a bromonium ion, and an iodonium ion are shown next. 

Acetylene reacts with fluorine with explosive violence. Reactions with other halogens, chlorine, bromine, and iodine are violent, too. Acetylene chloride, which is formed from addition reaction with chlorine, explodes spontaneously. It forms unstable acetylides with metals such as copper,... 

Reaction with Other Inorganic Halogen Compounds. Anhydrous HCl forms addition compounds at lower temperatures with halogen acids such as HBr and HI, and also with HCN. These compounds are stable at room temperature. 

In the preceding parts of Section 4.04.2.1.3 the electrophilic attack on pyrazolic nitrogen with the concomitant formation of different classes of N—R bond has been examined N—H (iv, v), N—metal (vi), N—C(sp ) (vii, viii, xi), N—C(sp ) (be, x, xi), N—SO2R (x), N—halogen (xii), N—O (xiii) and N—-N (xiv). In this last part the reaction with other Lewis acids leading to the formation of pyrazole N—metalloid bonds will be discussed, and the study of their reactivity will be dealt with in Section 4.04.2.3.lO(viii). 

Phosphoryl chloride (b.p. 105 °C) has been used extensively as a nonaqueous solvent (see Chapter 10). Reactions of PC13 with other halogens give mixed pentahalides. 

Boron reacts with halogens to form horon hahdes. The reaction is instantaneous with fluorine but occurs at elevated temperatures with other halogens. With chlorine, bromine and iodine, the formation of hahdes completes around 400°C, 600°C and 900°C, respectively. Again, the amorphous powder of the metal is more reactive than the crystalline form. 

Fluorine also reacts with other halogens, forming interhalogen compounds. While with bromine and iodine it reacts vigorously at ordinary temperatures, with chlorine the reaction occurs at 200°C. Such interhalogen products with these halogens include iodine heptafluoride, bromine trifluoride, bromine pentafluoride, and chlorine trifluoride. Metalloid elements, such as arsenic, silicon, selenium, and boron also inflame in a stream of fluorine, forming fluorides. 

Similar reactions occur with other halogens. Monohalides of indium include chloride, bromide and iodide. Monohalides are obtained by passing indium trihalides over heated indium ... 

The protocol is used for the preparation of 25 kg of the aldehyde in Banyu, and applied to the synthesis of a muscarinic receptor agonist. It is noteworthy that halogen-metal exchange reactions with other metal reagents such as butyllithium or isopropylmagnesium bromide led to more complex mixtures. The Banyu protocol was applicable to similar monoformylation reactions of dibromoheteroarenes (Table 12). 

These results indicate that if polydienes and similar polymers can be prepared quantitatively with tertiary amine terminal groups, then they can be combined with other halogen functional polymers using established techniques to create interesting new block copolymer systems. For example, consider the reaction between telechelic pyridine terminated polybutadiene and monofunctional bromine terminated polystyrene (equation 4) -the latter has been prepared in 95% yield. >it The product would be an ABA... 

REACTION OF ANTHRACENE WITH OTHER HALOGENATED SOLVENTS1.4... 

Similar reactions occur with other halogens, and every possible combination of bromine, chlorine, and iodine exists under appropriate conditions in aqueous solution ... 

Fluorine is simultaneously eliminated with other halogens if it is the only halogen vicinal to iodine, bromine or chlorine. The elimination tendency decreases in the series IF > BrF > C1F. The group CF2CHFX is relatively stable towards elimination and requires stronger reaction conditions. The dehalogenation of saturated fluorohalo compounds with zinc dust or zinc/ copper and zinc/silver couples is one of the most useful methods for the preparation of fluoroalkenes (see Table 8). Zinc/zinc(II) chloride has also been used instead of zinc alone. 

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