Silver nitrate, reaction with halides

Silver nitrate test The compound to be tested is treated with a few drops of 1% alcoholic silver nitrate. A white precipitate indicates a positive reaction. This could be due to either silver chloride (reaction with a reactive alkyl halide), silver alkynide (reaction with a terminal alkyne), or the silver salt of a carboxylic acid (reaction with a carboxylic acid). 

In the experiments that follow, eight representative alkyl halides are treated with sodium iodide in acetone and with an ethanolic solution of silver nitrate. Acetone, with a dielectric constant of 21, is a relatively nonpolar solvent that will readily dissolve sodium iodide. The iodide ion is an excellent nucleophile, and the nonpolar solvent, acetone, favors the Sn2 reaction it does not favor ionization of the alkyl halide. The extent of reaction can be observed because sodium bromide and sodium chloride are not soluble in acetone and precipitate from solution if reaction occurs. 

Silver Nitrate Test. Alkyl halides that undergo the S l substitution reaction react with alcoholic silver nitrate (AgNOs) to form a precipitate of the corresponding silver halide. 

In the former, it gives precipitates with halides (except the fluoride), cyanides, thiocyanates, chromates(VI), phosphate(V), and most ions of organic acids. The silver salts of organic acids are obtained as white precipitates on adding silver nitrate to a neutral solution of the acid. These silver salts on ignition leave silver. When this reaction is carried out quantitatively, it provides a means of determining the basicity of the acid... 

The indicator electrode employed in a potentiometric titration will, of course, be dependent upon the type of reaction which is under investigation. Thus, for an acid-base titration, the indicator electrode is usually a glass electrode (Section 15.6) for a precipitation titration (halide with silver nitrate, or silver with chloride) a silver electrode will be used, and for a redox titration [e.g. iron(II) with dichromate] a plain platinum wire is used as the redox electrode. 

As esters the alkyl halides are hydrolysed by alkalis to alcohols and salts of halogen acids. They are converted by nascent hydrogen into hydrocarbons, by ammonia into amines, by alkoxides into ethers, by alkali hydrogen sulphides into mercaptans, by potassium cyanide into nitriles, and by sodium acetate into acetic esters. (Formulate these reactions.) The alkyl halides are practically insoluble in water but are, on the other hand, miscible with organic solvents. As a consequence of the great affinity of iodine for silver, the alkyl iodides are almost instantaneously decomposed by aqueous-alcoholic silver nitrate solution, and so yield silver iodide and alcohol. The important method of Ziesel for the quantitative determination of alkyl groups combined in the form of ethers, depends on this property (cf. p. 80). 

Adsorption of Ag on the surface of PdO is also an interesting option offered by colloidal oxide synthesis. Silver is a well-known promoter for the improvement of catalytic properties, primarily selectivity, in various reactions such as hydrogenation of polyunsaturated compounds." The more stable oxidation state of silver is -F1 Aquo soluble precursors are silver nitrate (halide precursors are aU insoluble), and some organics such as acetate or oxalate with limited solubility may also be used." Ag" " is a d ° ion and can easily form linear AgL2 type complexes according to crystal field theory. Nevertheless, even for a concentrated solution of AgNOs, Ag+ does not form aquo complexes." Although a solvation sphere surrounds the cation, no metal-water chemical bonds have been observed. 

The reaction of alkyl halides with silver nitrate constitutes an extremely useful method for the synthesis of high purity nitrate esters on a laboratory scale. ° The driving force for these reactions is the formation of the insoluble silver halide. Reactions have been conducted under homogenous and heterogeneous conditions. For the latter a solution of the alkyl halide in an inert solvent like benzene or ether is stirred with finely powdered silver nitrate. However, this method has been outdated and reactions are now commonly conducted under homogeneous conditions using acetonitrile as solvent. 

Synthesis of nitrate esters from the reaction of alkyl halides with silver nitrate... 

Silver Halides. Taking silver nitrate as a reactant, prepare silver chloride, bromide, and iodide, Wash the precipitates with water by decantation and test the action of light, an ammonia solution, and a sodium thiosulphate solution on them. Explain the observed phenomena. Write the equations of the reactions. Explain why silver iodide dissolves in sodium thiosulphate and does not dissolve in an aqueous solution of ammonia. 

Ligand exchange reactions have been used to prepare mercury(II) trialkylarsine complexes.202 Reaction of AgN03-AsMe3 with mercury halides gave the mercury arsine and silver halide (equations 10 and 11). The silver nitrate complex was not characterized. 

Heavy-metal salts, particularly those of silver, mercury, and copper, catalyze SX1 reactions of alkyl halides in much the same way that acids catalyze the SN reactions of alcohols. A heavy-metal ion functions by com-plexing with the unshared electrons of the halide, thereby making the leaving group a metal halide rather than a halide ion. This acceleration of the rates of halide reactions is the basis for a qualitative test for alkyl halides with silver nitrate in ethanol solution ... 

The outstanding chemical characteristic of alkenyl halides is their general inertness in SN1 and SN2 reactions. Thus chloroethene fails to react with silver nitrate in ethanol (i.e., low SN1 reactivity), fails to react with potassium iodide in acetone (i.e., low SN-2 reactivity), and only reacts slowly with sodium hydroxide to give ethyne (low E2 reactivity). The haloalkynes, such as RC=C—Cl, are similarly unreactive. 

Reaction with ethanolic potassium hydroxide. Boil 0.5 ml of the compound with 4 ml of 0.5 m ethanolic potassium hydroxide under reflux for 15 minutes. Most alkyl halides and benzyl halides give a crystalline precipitate of the potassium halide. Dilute with 5 ml of water, acidify with dilute nitric acid and test with silver nitrate solution. 

The characteristic of the halides of the elements of the lithium group is that they are all soluble white salts, crystallising in cubes. In dilute solution they are all ionised, and even in strong solution a large percentage of ions are present. Hence they all react as metal ions and as halogen ions. Thus, for instance, with silver nitrate, which is the usual test for ionic chlorine, the following reaction takes... 

Alcohols, hydrocarbons, and their halide-containing derivatives, and their mixtures, are the most frequently used solvents (Solv). The majority of these reactions take place at room temperature or with slight heating, necessary for dissolution of the reagents. The transformation (3.199) was one of the first template reactions of the examined type [434]. In this reaction, the coordinatively unsaturated platinum complex is an N-base and silver nitrate is a Lewis acid ... 

The reaction of a compound with silver nitrate in ethanol is used as a chemical test to determine if the compound is an alkyl halide. The formation of a precipitate of the silver halide constitutes a positive test. 

A reluctant first-order substrate can be forced to ionize by adding some silver nitrate (one of the few soluble silver salts) to the reaction. Silver ion reacts with the halogen to form a silver halide (a highly exothermic reaction), generating the cation of the alkyl group. 

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