Ammonia, production related examples

The ketocarbene 4 that is generated by loss of Na from the a-diazo ketone, and that has an electron-sextet, rearranges to the more stable ketene 2 by a nucleophilic 1,2-shift of substituent R. The ketene thus formed corresponds to the isocyanate product of the related Curtius reaction. The ketene can further react with nucleophilic agents, that add to the C=0-double bond. For example by reaction with water a carboxylic acid 3 is formed, while from reaction with an alcohol R -OH an ester 5 is obtained directly. The reaction with ammonia or an amine R -NHa leads to formation of a carboxylic amide 6 or 7 ... 

Acrylonitrile Is produced from propene, ammonia, and oxygen by the following balanced equation (see Example 14-5) 2 C3 Hg + 2 NH3 + 3 O2 2 CH2 CHCN -1- 6 H2 O Relate the rates of reaction of starting materials and products. 

A number of routes are available for the synthesis of 2,2 -bipyridines where one of the pyridine rings is built up from simpler entities. For example, condensation of 2-(aminomethyl)pyridine (31) with acetaldehyde or acetylene over a silicon-alumina catalyst at 450°C gives 2,2 -bipyridine, ° whereas 2-cyanopyridine reacts with acetylene at 120°C in the presence of a cobalt catalyst to afford 2,2 -bipyridine in 95% yield.2-Acetylpyridine with acrolein and ammonia gives 2,2 -bipyridine in the presence of dehydrating and dehydrogenating catalysts, and related condensations afford substituted 2,2 -bipyridines. ° In a similar vein, condensation of benzaldehyde with 2 mol of 2-acetylpyridine in the presence of ammonia at 250°C affords 2,6-di(2-pyridyl)-4-phenylpyridine, ° and related syntheses of substituted 2,2 6, 2"-terpyridines have been described. Likewise, formaldehyde with two moles of ethyl picolinoylacetate and ammonia, followed by oxidation of the product and hydrolysis and decarboxylation, affords a good... 

As in the synthesis of other bipyridines, several routes to 4,4 -bipyridine have been devised where one of the pyridine rings is built up from simpler components. For example, a dimer of acrolein reacts with ammonia and methanol in the presence of boron phosphate catalyst at 350°C to give a mixture of products including 4,4 -bipyridine (3.4% yield), and in a reaction akin to ones referred to with other bipyridines, 4-vinylpyridine reacts with substituted oxazoles in the presence of acid to give substituted 4,4 -bipyridines. ° ° Condensation of isonicotinaldehyde with acetaldehyde and ammonia at high temperatures in the presence of a catalyst also affords some 4,4 -bipyridine, and related processes give similar results,whereas pyran derivatives can be converted to 4,4 -bipyridine (56% conversion), for example, by reaction with ammonia and air at 350°C with a nickel-alumina catalyst. Likewise, 2,6-diphenyl-4-(4-pyridyl)pyrylium salts afford 2,6-... 

Careful inspection of the reported photocatalytic reactions may demonstrate that reaction products can not be classified, in many cases, into the two above categories, oxidation and reduction of starting materials. For example, photoirradiation onto an aqueous suspension of platinum-loaded Ti02 converts primary alkylamines into secondary amines and ammonia, both of which are not redox products.34) ln.a similar manner, cyclic secondary amines, e.g., piperidine, are produced from a,co-diamines.34) Along this line, trials of synthesis of cyclic imino acids such as proline or pipecolinic acid (PCA) from a-amino acids, ornithine or lysine (Lys), have beer. successfuL35) Since optically pure L-isomer of a-amino acids are available in low cost, their conversion into optically active products is one of the most important and practical chemical routes for the synthesis of chiral compounds. It should be noted that l- and racemic PCA s are obtained from L-Lys by Ti02 and CdS photocatalyst, respectively. This will be discussed later in relation to the reaction mechanism. 

Different photoreactions can be initiated in structurally related complexes of a metal ion as a result of the intrinsic properties of the LMCT excited state and radical-ion pairs. The excited-state reactions of azido complexes of Co(III) are one example of this chemical diversity.106-109 Irradiation of Co///(NH3)5N2+ aqueous acidic solutions in the spectral region 214 nm < 2exc < 330 nm produces Coin(NH3)4(H20)N, 6 0.6, and Co(aq)2 +, molar ratio.93 The ammonia photoaquation has two sources that also account for the large quantum yield of the photoprocess. One source competes with the formation of Co(aq)2 + from radical-ion pairs. These pairs must be produced with a quantum yield 0.5. The second source is a process unrelated to the Co(aq)2 + production and it has a quantum yield excited state where a Co-NH3 bond has been considerably elongated and where the electronic relaxation of the excited state has been coupled with aquation. A second rationale for the large aquation quantum yield is that a reactive LF excited state is populated by the LMCT excited state. 

So far, all of the examples have involved primary amines. The reaction of ammonia with aldehydes and ketones also forms imines, but the products are unstable and cannot usually be isolated. If a secondary amine is used, an enamine, rather than an imine, is formed. An enamine has an amino group bonded to one of the carbons of a CC double bond. It is related to the imine in the same manner as an enol is related to a ketone (see Section 11.6). The mechanism for its formation can be outlined as follows ... 

Two further papers report lithium-ammonia reductive cleavage of some A3-THC-related compounds374 and selenium dioxide oxidation of A -THC and A6-THC.375 In the latter, it is shown that A -THC yields oxidation products predominantly from attack at C-6, whereas A6-THC is oxidized preferentially at the exocyclic allylic C-7 methyl group, to yield, for example, (269). 

The examination of structure/property relations of molecular educts and resulting ceramics required the synthesis of stoichiometrically and stmcturally different precursors. A variety of synthesis routes for Si-B-N-C precursors fiom organosilanes, silazanes, and boron compounds have been reported in recent years [3 - 5]. As an example, Riedel obtained a polymeric precursor via hydroboration of methylvinyldichlorosilane and subsequent condensation of the hydroboration product with ammonia (Eq. 1). Pyrolysis led to silicoboron carbonitride ceramics exhibiting thermal stability up to 2000 °C [6]. 

Another example which is directly related to industrial catalysis is the adsorption and decomposition of propene from a mixed oxide, namely FeSbOj- This material is used for the industrial production of acrolein and acrylonitrile (Yoshino et al., 1971). If the surface is dosed with both propene and ammonia, then all the reaction products in the industrial process are seen to evolve as shown in fig. 24 (Hutchings et al., 1991). Some intact propene desorbs at low temperatures, while the selective ammoxidation... 

Equation (5.5) is the mathematical expression of Avogadro s law, which states that at constant pressure and temperature, the volume of a gas is directly proportional to the number of moles of the gas present. From Avogadro s law we learn that when two gases react with each other, their reacting volumes have a simple ratio to each other. If the product is a gas, its volume is related to the volume of the reactants by a simple ratio (a fact demonstrated earlier by Gay-Lussac). For example, consider the synthesis of ammonia from molecular hydrogen and molecular nitrogen ... 

---