Amines from ammonium salts

As the amines become more weakly basic, the normal method of diazotization becomes progressively more difficult. The equilibrium between amine and ammonium salt increasingly favors the former which, usually because of its poor solubility in water, is prevented from taking part in the reaction. Research into the mechanism of diazotization has demonstrated that the important step is the addition of the nitrosating agent to the base of the amine. Thus, the acidity for each diazotization should be so chosen that the equilibrium concentration of base corresponds to that of its saturated solution. This rule leads to the use of higer concentrations of aqueous mineral acid for weakly basic amines. 

Rather than preforming the a-amino ketimines to be reduced, it is often advantageous to form in situ the more reactive iminium ions from a-aminoketones and primary amines or ammonium salts in the presence of the reducing agent, e.g., sodium cyanoborohydride. Use of this procedure (reductive amination) with the enantiopure a-aminoketone 214 and benzylamine allowed the preparation of the syn diamines 215 with high yields and (almost) complete diastereoselectivities [100] (Scheme 32). Then, the primary diamines 216 were obtained by routine N-debenzylation. Similarly, the diamine 217 was prepared using ammonium acetate. In... 

J. H. Brewster, E. L. Eliel, Carbon-Carbon Alkylations with Amines and Ammonium Salts , Org. React. 1953, 7, 99-197 [covers Michael Additions Starting from /3-(Dialkylamino) ketones, -esters or Nitriles],... 

Early work on 1,2-elimination in cyclopropanes centred on the thermal elimination of amines from cyclopropyltrialkylammonium salts 1). An elegant example is a route to optically active cyclopropenes involving the resolution of the acid (8, R = C02H), conversion to the quaternary ammonium salt (8, R = + NMe3) and elimination over platinised asbestos at 360 °C 18) ... 

Goethals, E. J., Schacht, E. H. Polyamines and Polyammonium salts derived from azetidine monomers, in Polymeric amines and ammonium salts (ed.) Goethals, E. J., p. 67, New York, Pergamon Press 1980, and references therein... 

Among the numerous derivatives useful in identifying amines are amides e.g., acetamides, benzamides, or sulfonamides) for primary and secondary amines quaternary ammonium salts (e.g., those from benzyl chloride or methyl iodide) or tertiary amines. 

The formation of amides from ammonium salts of oxygen acids is in fact only a part of the dissociation of the intermediate addition compound in amide formation from an amine and an acid. The formation of amide from ester and ammonia is similar to the formation of amide from... 

Dequaternization (s. a. Amines, tert., from ammonium salts, quaternary) 17, 984 Derivatives s. a. subentry derivatives... 

First of all, we collected the main techniques used in the kinetic studies of the reaction (reaction procedures, analytical methods, treatment of experimental data). In fact, unambiguous results can be obtained only if some basic conditions are observed. The survey of the literature shows a great diversity of the catalysts used in epoxy-carboxy esterifications or polyesterifications however, at least in the case of kinetic studies, tertiary amines and ammonium salts are largely predominant. From the fundamental studies carried out with organic models, and mostly in solution, several mechanisms were proposed involving the formation of a complex which can be cyclic or not. 

Note. Useful information can often be obtained by adding (i) dilute H,SO or (ii) dilute NaOH solution to an aqueous solution of the substance under investigation. A precipitate with (i) usually indicates an aromatic carboxylic acid from a metallic or from an ammonium salt. A precipitate or oil with (ii) usually indicates an aromatic amine from an amine salt. 

Their basicity provides a means by which amines may be separated from neutral organic compounds A mixture containing an amine is dissolved m diethyl ether and shaken with dilute hydrochloric acid to convert the amine to an ammonium salt The ammonium salt being ionic dissolves m the aqueous phase which is separated from the ether layer Adding sodium hydroxide to the aqueous layer converts the ammonium salt back to the free amine which is then removed from the aqueous phase by extraction with a fresh portion of ether... 

Ammonium fluorosulfate is produced from ammonium fluoride by reaction with sulfur trioxide, oleum, or potassium pyrosulfate, 1 2820 (48). Solutions of ammonium fluorosulfate show Htfle evidence of hydrolysis and the salt may be recrystallized from hot water. Ammonium fluorosulfate absorbs anhydrous ammonia to form a series of Hquid amines that contain 2.5—6 moles of ammonia per mole of salt (77). 

Salt formation with Brmnsted and Lewis acids and exhaustive alkylation to form quaternary ammonium cations are part of the rich derivati2ation chemistry of these amines. Carbamates and thiocarbamates are formed with CO2 and CS2, respectively the former precipitate from neat amine as carbamate salts but are highly water soluble. 

The reaction can be driven to the tetraalkoxide stage by addition of an amine or ammonia to scavenge the Hberated hydrochloric acid. The amine or ammonium hydrochloride that forms can be filtered from the reaction mass and the tetraalkyl titanate purified by distillation. If the reaction is mn in the starting alcohol as solvent, the chloride salts formed are in a finely divided state and difficult to filter. When the reaction is mn in the presence of an inert hydrocarbon solvent such as heptane or toluene, a much more readily filterable salt is obtained. The solution of cmde tetraalkyl titanate can be distilled to remove solvent and give a pure product (1,2). 

Miscellaneous Derivatives. Other derivatives of toluene, none of which is estimated to consume more than ca 3000 t (10 gal) of toluene aimuaHy, are mono- and dinitrotoluene hydrogenated to amines ben2otrich1 oride and chlorotoluene, both used as dye intermediates / 7-butylben2oic acid from / 7-butyltoluene, used as a resin modifier dodecyltoluene converted to a ben2yl quaternary ammonium salt for use as a germicide and biphenyl, obtained as by-product during demethylation, used in specialty chemicals. Toluene is also used as a denaturant in specially denatured alcohol (SDA) formulas 2-B and 12-A. 

The starting materials of the aldehyde method may be sulfonated. For example. Cl Acid Blue 9 [2650-18-2] Cl Food Blue 2 (Cl 42090), is manufactured by condensing a-(A/-ethylanilino)-y -toluenesulfonic acid with o-sulfobenzaldehyde. The leuco base is oxidized with sodium dichromate to the dye, which is usually isolated as the ammonium salt. In this case, the removal of the excess amine is not necessary. However, this color caimot be used in the food sector because separation of the chromium compounds from the dye is difficult. An alternative method which gives food-grade Cl Acid Blue 9 (14) and dispenses with the use of sodium dichromate employs oxidative electrolysis of the leuco base (49). 

For direct precipitation of vanadium from the salt-roast leach Hquor, acidulation to ca pH 1 without the addition of ammonia salts yields an impure vanadic acid when ammonium salts are added, ammonium polyvanadate precipitates. The impure vanadic acid ordinarily is redissolved in sodium carbonate solution, and ammonium metavanadate precipitates upon addition of ammonium salts. Fusion of the directly precipitated ammonium salts can yield high purity V20 for the chemical industry. Amine solvent extraction is sometimes used to recover 1—3 g/L of residual V20 from the directly precipitated tail Hquors. 

The benzylation of a wide variety of aHphatic, aromatic, and heterocycHc amines has been reported. Benzyl chloride is converted into mono-, di-, and tribenzyl amines by reaction with ammonia. Benzylaniline [103-32-2] results from the reaction of benzyl chloride with aniline. Reaction with tertiary amines yields quaternary ammonium salts with trialkylpbospbines, quaternary phosphonium salts and with sulfides, sulfonium salts are formed. 

Enamines in which the double-bond shift is sterically prevented afford only the ammonium salts. Their spectra in the C=C stretching vibration region does not differ greatly from that of the free amine spectrum (171). For example, neostrychnine (159) has vc c 1666 cm and its perchlorate at 1665 cm . Salts of quinuclideine (92) and the polycyclic alkaloid trimethylconkurchine have similar properties. 

The preparation of an alkene 3 from an amine 1 by application of a /3-elimination reaction is an important method in organic chemistry. A common procedure is the Hofmann elimination where the amine is first converted into a quaternary ammonium salt by exhaustive methylation. Another route for the conversion of amines to alkenes is offered by the Cope elimination. 

Methyl vinyl ketone 2 tends to polymerize, especially in the presence of a strong base the yield of annulation product is therefore often low. A methyl vinyl ketone precursor, e.g. 6, is often employed, from which the Michael acceptor 2 is generated in situ, upon treatment with a base. The quaternary ammonium salt 6 can be obtained by reaction of the tertiary amine 5, which in turn is prepared from acetone, formaldehyde and diethylamine in a Mannich reaction. 

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