Reactions in liquids

Inorganic amides contain the ion NH2". They are formed by the action of ammonia on metals or by the ammonolysis of nitrides. The heavy metal amides are prepared by meta-thetical reactions in liquid ammonia, e.g. 

In organic chemistry the term refers to compounds containing the NH2 ion or the > NH group. These are prepared by the action of heat on amides or by metathetica reactions in liquid ammonia. The heavy metal imides are explosive. 

Kapral R 1981 Kinetic theory of chemical reactions in liquids Adv. Chem. Phys. 48 71... 

VI,16. REACTIONS IN LIQUID AMMONIA. SOME ACETYLENIC COMPOUNDS ... 

Some reactions in liquid ammonia can be, or have to be, carried out very... 

An even less complicated reaction vessel may be used for reactions in liquid amtnonia which produce only a small amount of "heat" over a relatively long period and which proceed under homogeneous conditions. The conversion can then be performed in a one-necked flask with a stopper + gas outlet or small hole. 

For general practical instructions concerning reactions in liquid ammonia one should consult "Preparative Acetylenic Chemistry", Elsevier, Amsterdam, 1971. 

Fig. 3. Transferring reaction mixtures in liquid ammonia under ice. Fig. 4. Fast reactions in liquid ammonia.

Apparatus 2-1 flask (Fig. 1) for the addition of bromine and the coupling with propargylmagnesium bromide 6-1 flask (Fig. 4) for the reaction in liquid ammonia. 

TABLE 1-4 Effect of Iron on the Rate of Alkali Metal-Alcohol Reactions in Liquid Ammonia"- ... 

H. Smith, Organic Reactions in Liquid Ammonia, Interscience Publishers, New York, 1963. 

Common variants include reduction of a metal oxide or halide in the presence of N2 and the formation of a metal amide as an intermediate in reactions in liquid NH3 ... 

Redox reactions are particularly instructive. If all thermodynamically allowed reactions in liquid NH3 were kinetically rapid, then no oxidizing agent more powerful than N2 and no reducing agent more powerful than H2 could exist in this solvent. Using data for solutions at 25° ... 

Reactions in liquid ammonia (cf. Chapter 3, Section III) require a certain amount of care, since the solvent is low boiling (—33 ) and its fumes are noxious. Nevertheless, with reasonable caution, the preparation of an ammonia solution of sodium acetylide can be carried out as described. The reagent so prepared can then be directly used for displacements on alkyl halides or for additions to suitable carbonyl compounds. Examples of both reactions are given. 

There may, of course, be types of life with a wholly different chemical basis to our own, for example, a low temperature life on the outer planets which is based on reactions in liquid ammonia. 

North, A. M. (1964) The Collision Theory of Chemical Reactions in Liquids. Methuen, London [3.3]. 

Many of the reactions that take place in water have analogous reactions in liquid ammonia, (a) Write the chemical equation for the autoprotolysis of NH,. (b) What are the formulas of the acid and base species that result from the autoprotolysis of... 

For the liquid phase, the equilibrium ratios have only been estimated. For the range 233-263 K, its value was estimated in the range 4.5-5. corresponding to ca. 48 % dissociation. The heat of reaction in liquid phase was calculated to be in the range 0.624-0.756 kcal/mole (ref. 2). 

A. L. Harris, J. K. Brown, and C. B. Harris, The nature of simple photodissociation reactions in liquids on ultrafast time scales. Anna. Rev. Phys. Chem. 39, 341-366 (1988). 

Volume, pressure, temperature, and amounts of substances may change during a chemical reaction. When scientists make experimental measurements, however, they prefer to control as many variables as possible, to simplify the interpretation of their results. In general, it is possible to hold volume or pressure constant, but not both. In constant-volume calorimetry, the volume of the system is fixed, whereas in constant-pressure calorimetry, the pressure of the system is fixed. Constant-volume calorimetry is most often used to study reactions that involve gases, while constant-pressure calorimetry is particularly convenient for studying reactions in liquid solutions. Whichever type of calorimetry is used, temperature changes are used to calculate q. 

We know that ammonia is a gas at normal temperature and pressure, so it is sensible that the temperature must be lowered substantially to ran a reaction in liquid ammonia. Knowing that ammonia is liquid at 0.50 atm and 220 K, it makes sense that a still lower pressure is required to boil off the liquid at this temperature. 

Reactions in liquid medium can be carried ont by illumination with radiation of the relevant wavelengths generally in qnartz vessels of various configurations. 

Figure 5. Relative catalytic activities of CsxH3-xPWi2O40 (x=2.1,2.2 and 2.5) for various kinds of reactions in liquid-solid reaction system. Molecular size. Pore size. Catalytic activity was estimated fi-om the initial rate of the reaction. The activity of Cs2.5 for each reaction is taken to be unity. The figures in the parentheses are the reaction rates in the unit of mmol g-l h"l.

Franklin, E. C. (1905). Reactions in liquid ammonia. Journal of the American Chemical Society, Tl, 820-51. 

Snita, D., Lindner, J., Sevcikova, H., Kosek, J., Marek, M., Microreactors for ionic reactions in liquids and gels in electric field, in Ehreeld, W., Rinard, I. H., Wegeng, R. S. (Eds.), Process Miniaturization 2nd International Conference on Microreaction Technology, IMRET 2, Topical Conf. Preprints, pp. 140-145, AIChE, New Orleans (1998). 

Liquid-liquid reactors. Examples of liquid-liquid reactions are the nitration and sulfonation of organic liquids. Much of the discussion for gas-liquid reactions also applies to liquid-liquid reactions. In liquid-liquid reactions, mass needs to be transferred between two immiscible liquids for the reaction to take place. However, rather than gas-and liquid-film resistance as shown in Figure 7.2, there are two liquid-film resistances. The reaction may occur in one phase or both phases simultaneously. Generally, the solubility relationships are such that the extent of the reactions in one of the phases is so small that it can be neglected. 

The dynamic behavior of reactions in liquids may differ appreciably from that of gas phase reactions in several important respects. The short-range nature of intermolecular forces leads to several major differences in the macroscopic properties of the system, often with concomitant effects on the dynamics of chemical reactions occurring in the liquid phase. 

This chapter discusses the aspects of the kinetic behavior of reactions in liquid solutions that are most germane to the education of a chemical engineer. Particular emphasis is placed on catalysis by acids, bases, and enzymes and a useful technique for correlating kinetic data. 

Since the forces giving rise to the formation of chemical bonds are very short-range forces, reactions in liquid solutions will require some sort of encounter or collision between re-... 

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