Hydrogen halides, acidity

Similar mechanisms of course can be written for the reaction with the other hydrogen halide acids, and indeed for the relatively slow decomposition of N-chloroacetanilide in solutions of other strong acids15, viz. 

Hydrothermal synthesis in hydrogen halide acids leads directly to isolated single crystals of the ternary compounds suitable for x-ray investigation and physical measurement.1,2... 

No systematic study has been made to complete the list of substances given below. The reader is invited to look for further examples. The chalcogenide halides are formed by reaction of mixtures of the respective elements or binary components, or both, in the appropriate hydrogen halide acid under hydrothermal conditions. Temperatures are in the range of 500-100°C. The densities of the fluid are at least 55% of room-temperature values the corresponding pressures are not known in most cases. 

The peculiar circumstance of an essentially base free reaction medium now allows an entry to Lewis or Brpnsted acidic conditions, still in a one-pot fashion. In the presence of hydrogen halide acids y-hydroxy alkynones can be successfully cyclized to give 3-chloro-, 3-bromo-, and 3-iodofurans [194]. Therefore, a sequence... 

Liquid HjSO and hydrogen halides are acids capable of protonating trico-ordinated nitrogen. The order of hydrogen halide acidity is HI > HBr > HCl > HF. Weakly basic amines, e.g., Ph.N, react with HX or HjSO ... 

Hydrogen sulfide has been used in the presence of oxidative agents such as bromine/ iodine/ and ferric salts. In these reactions, there is always some strong acid present, mostly hydrogen halide. Acid catalysis is probably essential, as it appears that high concentrations of hydrogen chloride improve the yield. 

Thus, the differences in activities of protonic acids are due to the quality of the corresponding anion or to its tendency to form chemical bonds with the carbon cation. If the anion is unable to form such bonds without extensive regrouping or decomposition, the addition of the proton is followed by polymerization. Should the reactivity of the anion be suppressed by solvation, the tendency to polymerize is enhanced. Consequently, the efficiencies of protonic acids depend very much upon the polarities of the media and upon the reaction conditions [12, 13]. Also, the stronger the protonic acid the higher the reaction rate and the resultant degree of polymerization [14]. Generally, hydrogen halide acids do not initiate polymerizations of alkyl-substituted olefins. They may, however, initiate polymerizations of aryl-substituted olefins and vinyl ethers in polar solvents. The same is true of sulfuric acid [15]. 

It is known that, during oxidation, ethers of phosphorus-containing acids (phosphites) are easily converted into ethers of orthophosphoric acid (phosphates) by reacting with radicals according to Arbusov s reaction. li general, the P-O-C bonds are relatively unstable. They break when exposed to heat and are affected by alcohol, hydrogen halide acids and other polar reagents ... 

Cationic active centres are created by reaction of monomer with electrophiles (e.g. R ). Protonic acids such as sulphuric acid (H2SO4) and perchloric acid (HCIO4) are of use as initiators and involve addition of a proton (H" ) to monomer. However, hydrogen halide acids (e.g. HCl) are not suitable as initiators because the halide counter-ion rapidly combines with the carbocationic active centre to form a stable covalent bond. Lewis... 

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