Ammonia as base

The reaction between the copper derivative of pentafluorobenzene and chloracetyl chloride (ammonia as base) produces a little of the highly stable furan 8, an unusual result that has been regarded very tentatively as a Feist-Benary reaction with Cf,F5COCH2Cl as substrate.48... 

The complexes with unsubstituted and either alkyl- or aryl-substituted glyoximes have been prepared by the reaction of nickel(II) salts with the appropriate ligand in aqueous or ethanolic solution or an aqueous-ethanolic mixture. In most cases, the reaction is promoted by addition of ammonia as base and/or refluxing temperature. 

Chemically, the methylamines are slightly stronger than ammonia as bases. They hydrate in water solutions and neutralize acids to form methylammonium salts. They do not corrode iron and steel, but do attack copper and its alloys, zinc, and aluminum. The methylamines can form explosive compounds with mercury, so they must never be brought into contact with mercury. 

Alkali or ammonium chloride can be removed from the reaction mixture by sedimentation of filtration. Ammonia as base is definitely preferable in case of M(IV) derivatives to help avoid formation of stable bimetallic alkoxide derivatives [59], while Ln(0 Pr)3 and M (OR)s, M = Nb, Ta can be obtained in best yields using KOR because the bimetallic species with K are least stable thermodynamically [84]. 

By analogy, ammonium salts should behave as acids in liquid ammonia, since they produce the cation NH4 (the solvo-cation ), and soluble inorganic amides (for example KNHj, ionic) should act as bases. This idea is borne out by experiment ammonium salts in liquid ammonia react with certain metals and hydrogen is given off. The neutralisation of an ionic amide solution by a solution of an ammonium salt in liquid ammonia can be carried out and followed by an indicator or by the change in the potential of an electrode, just like the reaction of sodium hydroxide with hydrochloric acid in water. The only notable difference is that the salt formed in liquid ammonia is usually insoluble and therefore precipitates. 

Ammonia as a base. The ammonia molecule has a powerful affinity for protons and hence. 

Liquid ammonia, like water, is only a poor conductor of electricity. Ammonium salts dissolved in water behave as acids giving the ion NH4, whilst amides which give the ion NHj behave as bases. Thus the reaction ... 

The base strength of hydrazine is, however, lower than that of ammonia. As might be expected, hydrazine is readily soluble in water from which the hydrate N2H4.H2O can be crystallised. 

The ahphatic alkyleneamines are strong bases exhibiting behavior typical of simple aUphatic amines. Additionally, dependent on the location of the primary or secondary amino groups iu the alkyleneamines, ring formation with various reactants can occur. This same feature allows for metal ion complexation or chelation (1). The alkyleneamines are somewhat weaker bases than ahphatic amines and much stronger bases than ammonia as the piC values iadicate (Table 2). 

The Glaser coupling reaction is carried out in aqueous ammonia or an alcohol/ammonia solution in the presence of catalytic amounts of a copper-I salt. The required copper-II species for reaction with the acetylide anion R-C=C are generated by reaction with an oxidant—usually molecular oxygen. For the Eglinton procedure, equimolar amounts of a copper-II salt are used in the presence of pyridine as base. 

In many of the largest boiler plants around the world AYT programs are often employed that commonly provide for hydrazine (as an oxygen scavenger) and a volatile amine such as morpholine (to boost the pH level). Where funds are limited, however, some facilities instead use ammonia as a pH booster because it is a low-cost item with a low equivalent weight and a high DR. Unfortunately, this approach may lead to downstream problems as ammonia becomes less chemically bound with increases in FW pH and a weaker base as temperatures rise. Consequently, a point is reached when ammonia ceases to further influence the pH level upward. 

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)... 

To verify the presence of Zn2+ ions in the solution remaining after the first two steps, we add H2S followed by ammonia. The base removes the hydronium ion from the H2S equilibrium, which shifts the equilibrium in favor of S2- ions. The higher concentration of S2 ions increases the Qsp values of any remaining metal sulfides, such as ZnS or MnS, above their fCsp values, and they precipitate. 

Organic derivatives of ammonia are called amines. Because nitrogen is trivalent, amines can be primary (attached to one carbon), secondary (attached to two carbons), or tertiary. All amines are basic, and their strength as bases increases with the number of alkyl groups attached to the nitrogen that is, methyl amine is a stronger base than ammonia and trimethylamine is stronger than dimethylamine. Amines can be prepared from ammonia and an alkyl halide ... 

The introduction of conjugate acid-base pairs completes our inventory of acids and bases, hi addition to strong bases, ammonia, and amines, the anions of weak acids act as bases. 

In both cases the nitrogen atom uses its pair of nonbonding electrons to make a new covalent bond. This similarity led G. N. Lewis to classify ammonia as a base in its reaction with B (CH3)3 as well as in its reaction with H3 O . Whereas the Br< )nsted definition focuses on proton transfer, the Lewis definition of acids and bases focuses on electron pairs. 

Presently the catalytic selective NOx reduction by ammonia is efficient and widespread through the world for stationary sources. The remarkable beneficial effect of 02 for the complete reduction of NO into nitrogen is usually observed between 200 and 400°C. However, such a technology is not applicable for mobile sources due to the toxicity of ammonia and vanadium, which composes the active phase in vanadia-titania-based catalysts. Main drawbacks related to storing and handling of ammonia as well as changes in the load composition with subsequent ammonia slip considerably affect the reliability of such a process. On the other hand, the use of urea for heavy-duty vehicles is of interest with the in situ formation of ammonia. 

Le Corre and Treguer [49] developed an automated procedure based on oxidation of the ammonium ion by hypochlorite in the presence of sodium bromide followed by spectrophotometric determination of the nitrite. The standard deviation on a set of samples containing 1 p,g NH -N per litre was 0.02. This method was compared with an automated method for the determination of ammonia as indophenol blue. The results from the two methods are in good agreement. 

Synthesis using TPABr as structure-directing agent and ammonia, water, hexanediamine, n-butylamine, diethylamine, ethylenediamine, or triethanolamine as base (seeds of TS-1 were added to get smaller crystallites and 100% crystallinity) Synthesis of fibrous titanosilicate... 

But a word of caution species other than metal hydroxides can act as bases. Ammonia is such an example, since it can abstract protons in aqueous solution according to... 

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