Ammonia side products

By-Products. Almost all commercial manufacture of pyridine compounds involves the concomitant manufacture of various side products. Liquid- and vapor-phase synthesis of pyridines from ammonia and aldehydes or ketones produces pyridine or an alkylated pyridine as a primary product, as well as isomeric aLkylpyridines and higher substituted aLkylpyridines, along with their isomers. Furthermore, self-condensation of aldehydes and ketones can produce substituted ben2enes. Condensation of ammonia with the aldehydes can produce certain alkyl or unsaturated nitrile side products. Lasdy, self-condensation of the aldehydes and ketones, perhaps with reduction, can lead to alkanes and alkenes. 

Nitrile Intermediates. Most quaternary ammonium compounds are produced from fatty nitriles (qv), which are ia turn made from a natural fat or oil-derived fatty acid and ammonia (qv) (Fig. 2) (see Fats AND FATTY oils) (225). The nitriles are then reduced to the amines. A variety of reduciag agents maybe used (226). Catalytic hydrogenation over a metal catalyst is the method most often used on a commercial scale (227). Formation of secondary and tertiary amine side-products can be hindered by the addition of acetic anhydride (228) or excess ammonia (229). In some cases secondary amines are the desired products. 

The mechanism outlined above is supported by experimental findings. An intermediate 5 has been isolated, " and has been identified by and N-nuclear magnetic resonance spectroscopy. Side-products have been isolated, which are likely to be formed from intermediate 4. N-isotope labeling experiments have shown that only the nitrogen remote from the phenyl group is eliminated as ammonia. 

When the reagent is ammonia, it is possible for the initial product to react again and for this product to react again, so that secondary and tertiary amines are usually obtained as side products ... 

The synthesis of ethylenediamine (EDA) from ethanolamine (EA) with ammonia over acidic t3pes of zeolite catalyst was investigated. Among the zeolites tested in this study, the protonic form of mordenite catalyst that was treated with EDTA (H-EDTA-MOR) showed the highest activity and selectivity for the formation of EA at 603 K, W/F=200 g h mol, and NH3/ =50. The reaction proved to be highly selective for EA over H-EDTA-MOR, with small amounts of ethyleneimine (El) and piperazine (PA) derivatives as the side products. IR spectroscopic data provide evidence that the protonated El is the chemical intermediate for the reaction. The reaction for Uie formation of EDA from EA and ammonia required stronger acidic sites in the mordenite channels for hi er yield and selectivity. 

However, besides the SCR activity, the selectivity is an important parameter for the assessment of the catalysts. In case of the SCR reaction, the selectivity with respect to both the product nitrogen and the reactant ammonia has to be considered. The product selectivity is important, as side products such as N20 can be formed and the reactant selectivity is important, as ammonia can be converted to nitrogen not only in the SCR reaction but also by the selective catalytic oxidation with oxygen [54],... 

A simple and atom-economical synthesis of hydrogen halide salts of primary amines directly from the corresponding halides, which avoids the production of significant amounts of secondary amine side products, has been described by researchers from Bristol-Myers Squibb [227]. Microwave irradiation of a variety of alkyl halides or tosylates in a commercially available 7 m solution of ammonia in methanol at 100-130 °C for 15 min to 2.5 h followed by evaporation of the solvent provided the corre-... 

Substitution of the 4-nitro group in 3,4-dinitrofuroxan 1176 by ammonia occurs readily, even at low temperature. Subsequent treatment of the obtained amine, product 1177, with r-butylamine results in formation of 4-amino-2-(/-butyl)-5-nitro-l,2,3-triazole 1-oxide 1178. However, there must be some additional side products in the reaction mixture, as the isolated yield of compound 1178 is only 17%. Upon treatment with trifluoroperacetic acid, the r-butyl group is removed. The obtained triazole system can exist in two tautomeric forms, 1179 and 1180 however, the 1-oxide form 1179 is strongly favored (Scheme 195) <2003CHE608>. 

The baking process has remained much the same until the present day at a stoichiometric ratio of 1 4, phthalic anhydride or phthalic acid reacts with an ammonia releasing compound. The reaction may also start from other suitable materials, such as phthalic acid derivatives, including phthalic acid esters, phthalic acid diamide, or phthalimide. Appropriate ammonia releasing agents include urea and its derivatives, such as biuret, guanidine, and dicyanodiamide. The fact that a certain amount of urea decomposes to form side products makes it necessary to use excess urea. Approximately 0.2 to 0.5, preferably 0.25 equivalents of copper salt should be added for each mole of phthalic anhydride. 0.1 to 0.4 moles of molybdenum salt per mole of phthalic anhydride is sufficient. The reaction temperature is between 200 and 300°C. 

Urea acts not only as an ammonia source but also forms decomposition products, such as biuret and higher condensation products. 14C labeling has indicated that the carbon atom of the urea molecule is not incorporated into the phthalocyanine structure. Employing a phthalic anhydride molecule bearing one radioac-tively labeled carbonyl function affords labeled copper phthalocyanine and phthalimide (as a side product), while the liberated carbon dioxide was found not to show any radioactivity. Labeled carbon dioxide, on the other hand, has been obtained in corresponding experiments using 14C labeled urea. 

There is much evidence for this mechanism, e.g., (1) the isolation of 131,527 (2) the detection of 130 by l3C and 15N nmr,528 (3) the isolation of side products that could only have come from 129,529 and (4) l5N labeling experiments that showed that it was the nitrogen farther from the ring that is eliminated as ammonia.530 The main function of the catalyst seems to be to speed the conversion of 127 to 128. The reaction can be performed without a catalyst. OS 111, 725 IV, 884. Also see OS IV, 657. 

This route gives a much better yield and a purer compound than when K2[PtCl4] is treated with ammonia directly. A disadvantage, however, is the necessity to use silver salts (usually nitrate) with overnight stirring, resulting in the possibility of side products formed by hydrolysis of the intermediate aqua species cis-[Pt(NH3)2(H20)2]2+.12 We here present a rapid and facile one-step synthesis of cisplatin. The experimental conditions are based on Lebedinsky s method,8 slightly modified as specified. 

Here ArX is the halothiophene and ArY the product. The nature of the initiation and termination steps is not known. Thus irradiation of 3-bromothiophene in liquid ammonia in presence of potassium acetone enolate gives the monothienylation product (492 51%) and the dithienylation product (493 25%). Instead of employing photostimulation, the reaction can be brought about in lower yields by dissolving sodium or potassium metal in the liquid ammonia solution. Here the corresponding alcohol is a side product. 

Indeed, the Na-HMPA route consistently provided the cleanest products and has been the only synthesis to provide solutions of Na3[M(CO)4]. It is often important to use solutions rather than slurries of trianion salts to minimize the formation of side products during the reactions of these materials with electrophiles. Until recently, product separation from the viscous and high-boiling HMPA has always been a problem (and remains so in some cases). For example, addition of excess THF to solutions of Na3[M(CO)4] in HMPA invariably resulted in the formation of sticky solids that contained HMPA and did not analyze satisfactorily (14). But recently, it was discovered that addition of these HMPA solutions to excess liquid ammonia resulted in practically quantitative precipitation of tan to pale yellow brown solids, which provided satisfactory elemental analyses of unsolvated Na3[M(CO)4] (M = Mn, Re). Virtually all impurities remained in the HMPA-NHj filtrate [Eqs. (4) and (5)]. 

Trinuclear species have also been reported. A blue-black ruthenium violet, proposed to be [Ru3N2(NH3)8(OH)(OH2)5]5+ (pe( = 0.8 pB), has been isolated as a side-product in the preparation of ruthenium red from aqueous ammoniacal solution of RuCl3 (94). Reaction of (NH4)2[OsCl6] with ammonia gives a diamagnetic purple species, osmium violet, proposed to be [Os3N2(NH3)8(OH2)6]Cl6. The XPS data on... 

All nitrile and amine products, with the exception of PS-dendr-(NH2)32, could be purified by precipitation techniques. The polarity of the medium that was used for precipitation had to be increased with increasing generation, from MeOH to ammonia, although PS- enrf/--(NH2)32 was too polar to be precipitated even in ammonia. Colunm-chromatographic purification of the nitrile intermediates was possible up to PS-side products as for example... 

The reduction of nitriles is of wide scope and has been applied to many nitriles. When catalytic hydrogenation is used, secondary amines, (RCH2)2NH, are often side products.These can be avoided by adding a compound, such as acetic anhydride, which removes the primary amine as soon as it is formed, or by the use of excess ammonia to drive the equilibria backward. Sponge nickel or nickel on silica gel have been used for the catalytic hydrogenation of aryl nitriles to amines. 

Pyridine is not polarographically reducible in aqueous media in MeCN catalytic hydrogen evolution is the main reaction of protonated pyridine at the cathode [224]. Pyridine can, however, be reduced to piperidine at a lead cathode in 10% H2SO4 [225] the yield is very dependent on the purity of the lead and other components. Side products are a,a, a,y-, and y,)/-dipiperidyl. Pyridine may be reduced to a dimer in liquid ammonia [226]. In MeCN pyridine is reduced in a two-electron wave dihydropyridine and cyanomethylated tetra-hydropyridine are formed, the latter by attack of (CH2CN) on the dihydropyridine [227]. Electrochemical synthesis involving pyridine and its derivatives has been reviewed [Ic]. 

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