Acidity continued hydrogen halides

Surface-mediated addition of HC1 or HBr can be carried out in the presence of silica or alumina.150 The hydrogen halides can be generated from thionyl chloride, oxalyl chloride, oxalyl bromide, phosphorus tribromide, or acetyl bromide. The kinetic products from HC1 and 1-phenylpropyne result from syn addition, but isomerization to the more stable Z-isomer occurs upon continued exposure to the acidic conditions. 

Olefins, addition—Continued of diazoacetic ester, 498 of halo ethers, 232 of halogen, 106 of hydrogen cyanide, 603 of hydrogen halide, 105 of hypohalous acid, 109 of polyhalides, 107 to cyanides, 571 allylic bromination, 36, 104 condensation, with halides, 108 with phenols, 179 conversion to amides (Wi 11 gerodt),... 

Rhodium catalyzed carbonylations of olefins and methanol can be operated in the absence of an alkyl iodide or hydrogen iodide if the carbonylation is operated in the presence of iodide-based ionic liquids. In this chapter, we will describe the historical development of these non-alkyl halide containing processes beginning with the carbonylation of ethylene to propionic acid in which the omission of alkyl hahde led to an improvement in the selectivity. We will further describe extension of the nonalkyl halide based carbonylation to the carbonylation of MeOH (producing acetic acid) in both a batch and continuous mode of operation. In the continuous mode, the best ionic liquids for carbonylation of MeOH were based on pyridinium and polyalkylated pyridinium iodide derivatives. Removing the highly toxic alkyl halide represents safer, potentially lower cost, process with less complex product purification. 

The loss of weight, which originates from the reaction of a halide or oxide with a hydrogen form of a zeolite, i.e. from evolution of hydrohalic acid or water, can be measured by a balance. This thermogravimetric analysis may be combined with GC or MS measurements or with continuous titration. 

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