Ammonia clays

So now we have a modified method where one has ammonia, methylamine or ethylamine freebase saturated in a small amount of DMF. The author next suggested that a power pulse protocol would not necessarily be needed, but that the power output from the microwave should be between 20-40% of full power. Also, the water in the clay would still be needed for the reaction. 

Resorcinol Derivatives. Aminophenols (qv) are important intermediates for the syntheses of dyes or active molecules for agrochemistry and pharmacy. Syntheses have been described involving resorcinol reacting with amines (91). For these reactions, a number of catalysts have been used / -toluene sulfonic acid (92), zinc chloride (93), zeoHtes and clays (94), and oxides supported on siUca (95). In particular, catalysts performing the condensation of ammonia with resorcinol have been described gadolinium oxide on siUca (96), nickel, or zinc phosphates (97), and iron phosphate (98). 

After 30 minutes the solid sulfinic acid is separated on a fritted-glass filter. The sulfinic acid is dissolved from the filter by a mixture of 750 ml. of ether and 750 ml, of methylene chloride. The solution is dried over calcium chloride and evaporated to dryness under reduced pressure (bath temperature 25°) (Note 5). The residue is suspended in 50 ml. of water, and small portions of dilute ammonia are added to the well-stirred suspension until it has a pH of 9 (Note 6). Insoluble impurities are separated by filtration, and 2-nitrobenzenesulfinic acid is precipitated from the filtrate by adding 5-ml. portions of 6N hydrochloric acid with cooling the sulfinic acid precipitated by each portion of acid is separately collected on a Buchner funnel (Note 7). The acid, a pale yellow solid, is dried on a clay plate in a vacuum desiccator over potassium hydroxide pellets, m.p. 120-125° (dec.), weight 9.4-14.9 g. (50-80%). If the 2-nitrobenzenesulfinic acid is to be used for the hydrogenation of the next step high purity is required, and it is generally advisable to reprecipitate the acid once more in the same way (Note 8). 

The rapid synthesis of heteroaromatic Hantzsch pyridines can be achieved by aromatization of the corresponding 1,4-DHP derivative under microwave-assisted conditions [51]. However, the domino synthesis of these derivatives has been reported in a domestic microwave oven [58,59] using bentonite clay and ammoniiun nitrate, the latter serving as both the source of ammonia and the oxidant, hi spite of some contradictory findings [51,58,59], this approach has been employed in the automated high-throughput parallel synthesis of pyridine libraries in a 96-well plate [59]. In each well, a mixture of an aldehyde, ethyl acetoacetate and a second 1,3-dicarbonyl compound was irradiated for 5 min in the presence of bentonite/ammonium nitrate. For some reactions, depending upon the specific 1,3-dicarbonyl compound used. 

Pyridines are traditionally prepared using the Hantzsch reaction, a condensation between 2 mol of a 6-ketoester, 1 mol of an aldehyde and 1 mol of ammonia. The product of this reaction is a 1,4-dihydropyridine which can be further oxidized to the corresponding pyridine compound (as 155 in Scheme 54). A first report described the Hantzsch reaction carried out under microwave irradiation on Bentonite clay and ammonium nitrate as ammonia... 

Bentonite is an impure clay that is formed by weathering of volcanic tuffs. It contains a high content of montmorillonite. Bentonites exhibit properties such as ability to swell, ion exchange, and thixotropy. Properties can be modified by ion exchange, for example, exchange of earth alkali metals to alkali metals. The specific surface can be modified with acid treatment. Organophilic properties can be increased by treatment with quaternary ammonia compounds. 

In 1956 Brown, in a series of patents(68-75), disclosed that clays could be treated with di-, tri-, or tetra-substituted ammonia derivatives. Later, McLaughlin, et al.(76,77), introduced cationic polymers as permanent clay protective chemicals. A series of published results describing laboratory and field applications soon became available(78-81). Structural details of the cationic polymers appeared in patents(82-85). In general the polymers are polyamine derivatives, mostly quaternary in nature. Theng(86,87) has discussed how the multiple cationic centers in these polymers can interact and permanently protect clays. Callaway(88) et al. has noted that cationic polymers may interfere with the performance of crosslinked fracturing fluids. 

Figure 3. The general nitrogen model for illustrating the bio geochemical cycling in Forest ecosystems. Explanations for the fluxes 1, ammonia volatilization 2, forest fertilization 3, N2-fixation 4, denitrification 5, nitrate respiration 6, nitrification 7, immobilization 8, mineralization 9, assimilatory and dissimilatory nitrate reduction to ammonium 10, leaching 11, plant uptake 12, deposition N input 13, residue composition, exudation 14, soil erosion 15, ammonium fixation and release by clay minerals 16, biomass combustion 17, forest harvesting 18, litterfall (Bashkin, 2002).

Soil. In soils, Klebsiella pneu/nonrae metabolized bromoxynil to 3,5-dibromo-4-hydroxybenzoic acid and ammonia (McBride et al., 1986). In soil, bromoxynil undergoes nitrile and then amide hydrolysis yielding 3,5-dibromo-4-hydroxybenzoic acid and 3,5-dibromo-4-hydroxybenzamide (Smith, 1988). Degradation was rapid in a heavy clay soil, sandy loam, and clay loam. After 1 wk, only 10% of the applied dosage was recovered. 

Nitric acid (HNO ) is an important commercial chemical and was manufactured commercially to produce fertilizers and explosives as well as plastics and many other products. In 1902 a German chemist, WiUrehn Ostwald (1853—1932), developed a process wherein at high temperatures he used platinum catalysts to convert ammonia into nitric acid. When nitric acid is reacted with glycerol, the result is nitroglycerine—an unstable explosive unless dissolved in inert material, such as clay. It can then be stabihzed as dynamite. 

The number of acid sites on pillared clays was determined by means of temperature programmed desorption (TPD) of ammonia. In each TPD experiment, a sample weighing about 0.5 g was treated in vacuo for 1 h at a given temperature in the range 400 - 600°C. Ammonia was adsorbed at a desired temperature (100-300°C) for 30 min and evacuated for 30 min. This sample was heated to 700°C at a rate of 10°C/min and desorbed ammonia was monitored by thermal conductivity detector. As water was desorbed simultaneously with ammonia, the ammonia TPD spectrum was obtained by point-by-point subtraction of the water desorption spectrum obtained with the sample which had not adsorbed ammonia. 

Figure 1 shows the ammonia TPD spectra obtained with Al-mont and Al-sapo calcined at 400°C. Al-sapo was more acidic than Al-mont. It is generally assumed that the acid sites on pillared clays are attributable either to the silicate layer of clays or to the pillars. It was shown previously [8,9] that the acidity increased with increasing number of pillars. The number of pillars, however, cannot serve to elucidate the difference in acidity between Al-mont and Al-sapo because more acidic Al-sapo has smaller number of pillars than Al-mont, being 2.20 and 3.3 imiol/g, respectively. Many investigators have proposed... 

Solid NH4N03 is very hygroscopic (i.e., it picks up water from the air). Nonoxidizable drying agents such as clays are usually added to suppress this effect and the consequent caking. Calcium carbonate (chalk, crushed limestone) may be added to form a nonexplosive product with 26% N. Alternatively, ammonium nitrate may be marketed as an aqueous solution, also containing ammonia and urea. 

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