Ammonia-hydrogen exchange reaction

Fig. 1. Apparatus for studying hydrogen exchange reactions in liquid ammonia.

Table 6 shows the acceleration of the hydrogen exchange reaction in ammonia when Ca(N03)2 is dissolved in it. The rate constant without the addition of the salt is denoted by k0. 

So far we have not considered the problem of the transmission of substituent effects in organic molecules during hydrogen exchange reactions in liquid ammonia, and have not compared the regularities... 

Hydrogen isotope exchange reactions have long been used to prepare deuterated organic compounds (Miklukhin, 1961). The extension of the range of substances which can take part in hydrogen exchange reactions, which has been the result of the use of liquid deuterio-ammonia as the reactive medium, has opened new possibilities as far as such preparations are concerned (Shatenshtein and Izrailevich, 1957 Bardasova et al., 1960). 

Hydrogen exchange reactions in liquid ammonia can be used to prepare many organic compounds labelled with tritium or deuterium. 

Hydrogen exchange reactions of heteroaromatics64 69, 65 carried out in strongly alkaline media, such as potassium amide/liquid ammonia, alcoholic solutions of alkoxides, or solutions of potassium <-butoxide in dimethyl sulfoxide, proceed through an entirely different mechanism (sometimes called protophilic ) involving a carbanion-type intermediate66, 67 they are not electrophilic substitutions as such and will not be treated in this review. 

Because of the reduced rate of the deuterium exchange reaction at —50°C, the stages of the cold tower (D) are to be of the type developed by Sulzer [LI ] for the ammonia-hydrogen exchange process and used in the Maangarbe plant. Sec. 9.1. For the methylamine-hydrogen system at —50°C, a stage efficiency of 70 percent has been obtained [W6]. 

Kinetic studies of base-catalysed hydrogen exchange have been carried out by Roberts, by Shatenshtein, and by Streitweiser and their coworkers. In earlier work, potassium amide was used as base in liquid ammonia as solvent, whereas later workers used lithium and caesium cyclohexylamides in cyclohexylamine. The reaction can be represented by equilibria (239) and (240)... 

Exchange reactions, hydrogen isotope, of organic compounds in liquid ammonia, 1, 156 Exchange reactions, oxygen isotope, of organic compounds, 2, 123 Excited complexes, chemistry of, 19,1 Excited molecules, structure of electronically, 3, 365... 

Hydrogen isotope exchange reactions of organic compounds in liquid ammonia, 1, 156... 

---