Reagent ammonia

The same reagents used for SNCR can also be used for SCR service including anhydrous ammonia (NH3), aqueous ammonia (NH4OH), or urea (NH2-CO-NH2). The amount of ammonia reagent required to remove NO is slightly above a 1 1 stoichiometric ratio of NH3 to NO accounting for maldistribution and allowable NH3 slip. Therefore, if each mole of injected urea or ammonia reduces NO to the theoretical maximum amount, utilization is 100%. One hundred percent chemical utilization is approached in SCR systems, but in SNCR systems the value ranges from 30 to 60%. 

A C—N disconnection of a primary amine gives rise to the carbocation and amide anion synthons. It might be predicted therefore that treatment of an alkyl halide with ammonia (reagents equivalent to the above synthons) under pressure would constitute a suitable synthesis of a primary amine. In practice, however, the yield is poor since a mixture of all three classes of amines, together with some of the quaternary ammonium salt, is obtained, owing to more ready further alkylation of the sequentially formed products. 

Raw stock dihydroxydiphenylsilane (14.5-16.5% of hydroxyl groups, pH of the aqueous extract is 6-7) triacetoxymethylsilane (toluene solution, the semi-product of polyphenylsilsesquioxane, which is obtained in the acetylation of phenyltrichlorosilane aqueous ammonia (reagent grade, at least 25% of ammonia, not more than 0.002% of carbonates, not more than 0.0001% of chlorides), B brand of coal toluene (at least 95% (vol.) of the... 

Such a diagram is represented in Fig. 3. The acid predominance zone corresponds to the upper part of the diagram, that is, to pH and potential conditions so that the point representing the system is above the E° versus pH curve. Conversely, the aldehyde predominates when the system is located under this boundary. To illustrate the practical interest of these diagrams, let us refer to the classic test of the silver mirror, which corresponds to aldehydes oxidation by the silver nitrate-ammonia reagent. 

Tetraethoxysilane (TES 28 SQ) and aqueous ammonia (reagent grade, 32 wt%) were a gift from Merck KGaA, Darmstadt, Germany. 2-propanol (99+ %), n-dodecylamine (98 %) and n-hexadecylamine (90 %) were purchased from Aldrich, Steinheim, Germany. 

Many substituted tricycloalkanones 22 have been made by copper-catalyzed intramolecular cycloaddition of diazoketones to cycloalkenes. Cleavage of these compounds with the lithium/ammonia reagent (Table 13) provides a useful alternative to acid-catalyzed ring-opening reactions (see Section 2.4.1.3.4.) because it often leads to cleavage in a different mode. 

Conjugated dienes are readily reduced to the 1,4-dihydro derivatives with metal-ammonia reagents in the absence of added proton donors. For example, isoprene is reduced to 2-methyl-2-butene by sodium in ammonia, by way of an intermediate radical anion (7.41). The protons required to complete the reduction are supplied by the ammonia. 

Nickd oxide, ammoniaeal (reagent for silk). Dissolve 5 g of nickel sulfate in 100 mL of water, and add sodium hydroxide solution until nickel hydroxide is completely precipitated. Wash the precipitate well and dissolve in 25 mL of concentrated ammonium hydroxide and 25 mL of water. 

Gas chromatography-mass spectrometry (GC-MS) was performed with a Fin-nigan MAT (San Jose, CA) model 4021B quadrupole mass spectrometer interfaced to a Hewlett Packard 5890 GC equipped with an on-column injector. Mass spectra during GC-MS were obtained by chemical ionization with ammonia reagent gas at a source pressure of 0.3 torr. 

The use of an appropriate washing solution is also important. The alcoholic ammonia (reagent B) used not only facilitates the removal of excess silver, but also the subsequent dehydration of the tissue. 

The determination of ammonia should be done without delay (OJ-1 minute) after adding enzyme to the two cold blanks so that no hydrolysis of urea takes place. This is very slow at room temperature (25°C) but not negligible. It is stopped completely when the pH is elevated after adding the ammonia reagents. 

Alternatively, the ammonia treatment can be carried out by simply opening the synthesis column and carefully transferring the solid support into a 16-mL polypropylene test tube. The appropriate ammonia reagent is added (8 mL), the tube is sealed, and the mixture incubated at the desired temperature. On completion, the solution is filtered, then frozen (dry ice/ethanol bath), and finally, lyophilized to dryness. (Note here, filtration is necessary to remove the CPG glass beads that interfere with the subsequent desilylation step.)... 

Figure 8 Typical fingerprint mass spectra for a peppermint oil obtained using an Agilent MS chemical sensor in three different modes (a) electron impact ionization, (b) positive chemical ionization with methane reagent gas, and (c) positive chemical ionization with ammonia reagent gas.

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