Hydrogen-halide reactions

Because phenols are not converted to aryl halides by reaction with hydrogen halides, reaction proceeds no further than shown in the preceding general equation. For example. 

The reversible hydrogenolysis of trfl -(Ph2MeSi)2Pt(PMe2Ph)2 has been discussed in Sections II,B,4 and II,B,7. A mechanism similar to that postulated for hydrogen halide reactions [e.g., Eq. (78)] has been suggested 71, 114) such a dihydride intermediate has not been detected, but some support comes from the identification of H2XSiPtl2(H)(PEt3)2 (X = Cl, I), as shown in Eq. (79) 27). Further discussion is in Section III. 

Further examples of the conversion of methoxy-l,10-phenanthrolines into hydroxy-1,10-phenanthrolines by the usual hydrogen halide reactions have been reported.98,214 4,7-Bis-phenoxy-1,10-phenanthroline is converted into 4,7-diamino-1,10-phenanthroline by ammonium chloride at high temperatures.98... 

Examples include pyrolysis of an alkylbenzene homogeneous aldehyde hydrogenation olefin hydroformylation to alcohol with paraffin by-product formation, aldehyde condensation to heavy ends, and olefin isomerization cyclo-addition reactions and hydrogen-halide reactions. 

Reactions of Alcohols and Ethers with Hydrogen Halides Reaction of the C-0 Bond by Nucleophilic Substitution... 

The finite-resolution density of reactive states introduced in Sec. II is especially useful for analyzing the halogen-hydrogen halide reactions because, as stated above, the features due to quantized transition states are partially obscured in these systems by a number of narrow resonances associated with other regions of the potential energy surfaces. Therefore the accurate cumulative reaction probabilities N°(E) were convoluted with a Gaussian function of variable width F to obtain finite-resolution cumulative reaction probabilities N°(E F). Analysis of dN°(E F)/dE reveals the influence of quantized transition states underlying the narrower dynamical features of N°(E). 

Reactions of hydrogen atoms with hydrogen halides have two competing reaction pathways abstraction and exchange. The homologous series of hydrogen halide reactions H + HX (X = F, Cl, Br, I) has been used to observe this competi-... 

As a center of high electron density, the triple bond is readily attacked by electrophiles. This section describes the resnlts of three such processes addition of hydrogen halides, reaction with halogens, and hydration. The hydration is catalyzed by mercury(II) ions. As is the case in electrophilic additions to unsymmetrical alkenes (Section 12-3), the Markovnikov rule is followed in transformations of terminal alkynes The electrophile adds to the terminal (less snbstituted) carbon atom. 

Note that in this reaction the two byproducts of the reaction (HCl and SO ) are both gases. These escape from the reaction mixture, leaving the halogenoalkane, without the need to distil it off as in the hydrogen halide reaction. 

The availability of well-characterized pulsed hydrogen halide chemical lasers has permitted the application of these methods to a variety of chemical reactions which generate vibrationally excited hydrogen halide reaction products. As tunable infrared laser sources are being more extensively developed, these methods will undoubtedly be applied to a much larger class of reactions. 

Introduction to Addition Reactions Reactions of Alkenes—The characteristic reaction of alkenes is the addition of one substituent to each of the carbon atoms in the double bond (reaction 27.7). A variety of addition reactions are possible hydrogenation addition of hydrogen halides (reaction 27.8) hydration (reaction 27.9), producing a vicinal dihalide or a geminal dihalide and halogenation (reaction 27.10). In these reactions, a transfer of electron density occurs from the tt bond of the alkene to an electrophilic atom. In all these reactions— except halogenation— the electrophilic atom tends to add to... 

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