Hydrogen halides reacting with

You will remember that, when a hydrogen halide reacts with an unsymmetrical alkene, such as propene, two products are formed 2-bromopropane and 1-bromopropane. 

The relative ease with which hydrogen halides react with alkenes is in the order HI > HBr > HCl > HF. This is the same as their relative acidities (see Section 4.3.2) and indicates that protonation of the alkene is the rate-limiting step for the addition reaction. 

All hydrogen halides react with H2O to produce hydrohalic acids that ionize. 

Hydrogen halides react with oxetanes to give 3-halo alcohols. The acid-catalyzed hydrolysis yields 1,3-diols. 

Hydrogen halides react with dialkyl H-phosphonates to form monoesters of H-phosphonic acid and alkyl halides as a result of nucleophiUc attack of the halide anion at the a-carbon atom of the alkoxy group [300]. 

Among the hydrogen halides only hydrogen bromide reacts with alkenes by both electrophilic and free radical addition mechanisms Hydrogen iodide and hydrogen chlo ride always add to alkenes by electrophilic addition and follow Markovmkov s rule Hydrogen bromide normally reacts by electrophilic addition but if peroxides are pres ent or if the reaction is initiated photochemically the free radical mechanism is followed... 

In media such as water and alcohols, fluoride ion is strongly solvated by hydrogen bonding and is neither very basic nor very nucleophilic. On the other hand, the poorly solvated, or naked, fluoride ions that aie present when potassium fluoride dissolves in benzene in the presence of a crown ether aie better able to express their anionic reactivity. Thus, alkyl halides react with potassium fluoride in benzene containing 18-crown-6, thereby providing a method for the preparation of otherwise difficultly accessible alkyl fluorides. 

Reaction with Hydrogen Halogens react with hydrogen gas to yield hydrogen halides, HX ... 

Various lead halide sulfides are reported in the literature. They precipitate when acidic solutions of lead halides react with hydrogen sulfide. Most probably the lead(II) chaicogenide halides described below are the only stable ones among these compounds. The conditions for the syntheses of these materials are given in Table V. 

With Acyl Halides, Hydrogen Halides, and Metallic Halides. Ethylene oxide reacts with acetyl chloride at slightly elevated temperatures in the presence of hydrogen chloride to give the acetate of ethylene chlorohydrin (70). Hydrogen halides react to form the corresponding halohydrins (71). Aqueous solutions of ethylene oxide and a metallic halide can result in the precipitation of the metal hydroxide (72,73). The halides of aluminum, chromium, iron, thorium, and zinc in dilute solution react with ethylene oxide to form sols or gels of the metal oxide hydrates and ethylene halohydrin (74). 

Hydrogen halides react vigorously with vinyl ethers to give 1-haloethyl ethers, which are reactive intermediates for further synthesis. Conditions must be carefully selected to avoid polymerization of the vinyl ether, Hydrogen cyanide adds at high temperature to give a 2-alkoxypropioni-trile. 

Halides react with carbon monoxide, usually with palladium complex catalysts, in the presence of hydrogen donors, to give aldehydes (equation 147). 

The popularity of the Nef reaction is due in part to the ready availability of nitro compounds. Primary and secondary halides react with sodium nitrite in dimeAyl sulfoxide (DMSO) or dimethylform-amide (DMF) to give useful yields of nitro compounds. Primary amines can be oxidized to nitro compounds with potassium permanganate, m-chloroperbenzoic acitP or ozone. Chlorination of oximes with hypochlorous acid and reduction with magnesium, zinc or hydrogen/lpalladium gives secondary nitro compounds. Stabilized carbanions can be nitrated by treauitent with a nitrate ester, and enol acetates are nitrated by acetyl nitrate to give nitro ketones. ... 

This topic is discussed in detail in Chapter 9 and only an outline is presented here. When simple aryl halides react with strong bases such as the amide ion, NH2 , a hydrogen atom adjacent to the C-halogen unit is abstracted by the base. The resulting carbanion acts as a nucleophile... 

Ruthenium bis (hydrogen dihydride), reacted with alkyl and aryl halides to form a five-coordinate complex ... 

The accidental observation in 1957 that allyl halides reacted with tin hydrides not by addition across the double bond, but by replacement of the halogen by hydrogen, provided the basis for the extensive use which the tin hydrides (Section 15.3.5), distannanes (Section 18.2.3), allylstannanes (Section 9.1.3.3), and related compounds now find in organic synthesis. The reaction involves bimolecular homolytic substitution (Sh2) at the halogen centre, and ab initio calculations indicate that, when R = H, R = Me, and X = Cl, Br, or I, the transition state is colinear, as illustrated in equation 20-18.58... 

Some metal halides react with water to produce the metal oxide and the appropriate hydrogen halide (see photo). For example,... 

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