Free ammonia

Boil a mixture of 5 ml. (4 g.) of acetonitrile and 75 ml. of 10% aqueous sodium hydroxide solution in a 200 ml. flask under a refluxwater-condenser for 30 minutes, when hydrolysis will be complete. Detach the condenser and boil the solution in the open flask for a few minutes to drive off ull free ammonia. Then cool the solution, and add dilute sulphuric acid (i volume of concentrated acid 2 volumes of water)... 

Hydrolysis of benzonitrile to benzoic acid. BoU 5 -1 g. (5 ml.) of benzo-nitrUe and 80 ml. of 10 per cent, sodium hydroxide solution in a 250 ml. round-bottomed flask fitted with a reflux water condenser until the condensed liquid contains no oUy drops (about 45 minutes). Remove the condenser, and boU the solution in an open flask for a few minutes to remove free ammonia. Cool the liquid, and add concentrated hydrochloric acid, cautiously with shaking, until precipitation of benzoic acid is complete. Cool, filter the benzoic acid with suction, and wash with cold water dry upon filter paper in the air. The benzoic acid (5-8 g.) thus obtained should be pure (m.p. 121°). Recrystal-lise a small quantity from hot water and redetermine the m.p. 

Nessler s reagent (for free ammonia) dissolve 50 g of K1 in the least possible amount of cold water add a saturated solution of HgClj until a very slight excess is indicated add 400 mL of a 50% solution of KOH allow to settle, make up to a liter with water, and decant. 

Recovery of Ammonia. The filter Hquor contains unreacted sodium chloride and substantially all the ammonia with which the brine was originally saturated. The ammonia may be fixed or free. Fixed ammonia (ammonium chloride [12125-02-97]) corresponds stoichiometrically to the precipitated sodium bicarbonate. Free ammonia includes salts such as ammonium hydroxide, bicarbonate, and carbonate, and the several possible carbon—ammonia compounds that decompose at moderate temperatures. A sulfide solution may be added to the filter Hquor for corrosion protection. The sulfide is distilled for eventual absorption by the brine in the absorber. As the filter Hquor enters the distiller, it is preheated by indirect contact with departing gases. The warmed Hquor enters the main coke, tile, or bubble cap-fiUed sections of the distiller where heat decomposes the free ammonium compounds and steam strips the ammonia and carbon dioxide from the solution. 

Glutamic acid dehydrogenase is widely distributed in microorganisms and higher plants as a catalyst in the synthesis of L-glutamic acid from a-ketoglutaric acid and free ammonia. Transaminase is contained in a wide variety of microorganisms. 

In the semidirect process, (Fig. 23) the taw coke oven gas is cooled to condense tar and ammonia Hquor. The heavy layer, tar phase, is pumped to storage and the aqueous layer containing free and fixed ammonia is subsequendy processed in a stiH operation. Free ammonia is that which is in a form which readily dissociates by heat. Fixed ammonia is in a form which requites the presence of an alkaH, such as milk of lime, to effect the ammonia release. 

Hypochlorous acid reacts very rapidly and quantitatively with a slight excess of free ammonia forming monochloramine, NH2CI, which reacts at a slower rate with additional HOCl forming dichloramine, NHCI2. Trichloramine is formed when three moles of HOCl are added per mole of ammonia between pH 3—4 (100). Hypochlorous acid in the form of chlorine or hypochlorite is used in water treatments to oxidize ammonia by the process of break-point chlorination, which is based on formation of unstable dichloramine. The instabiHty of NHCI2 is caused by presence of HOCl and NCl (101,102). The reaction is most rapid at a pH of about 7.5 (103). Other nitrogen compounds such as urea, creatinine, and amino acids are also oxidized by hypochlorous acid, but at slower rates. Unstable iV-chloro compounds are intermediates in deammination of amino acids (104,105). 

The almost quantitative formation of free ammonia can be used for an estimation of the oxazirane. With pure oxaziranes, ammonia yields of 93-96% are obtained. 

Every step of the Bucherer reaction is reversible, and the reverse sequence is also of synthetic value. The equilibrium can be shifted by varying the concentration of free ammonia. ... 

The alkali-soluble protein of the peel of lemons treated with hydrogen sulfide, sulfur dioxide, and sulfuric acid contained radioactive sulfur, but the fruit treated with hydrogen sulfide had a significantly lower per cent specific activity in the alkali-soluble protein fraction than did the sulfur dioxide or sulfuric acid treated fruits (Table VII). These results suggest that sulfur dioxide and sulfuric acid react with protein more directly, while hydrogen sulfide perhaps must be oxidized first, as indicated in Table III. It also appears (from Table VII) that the alkali-soluble protein may have been dismuted as the amounts isolated were less in both the hydrogen sulfide and sulfur dioxide treated fruit than in the incubated or nonincubated controls. Other evidence of dismutation has been obtained in experiments where incubation at 60° C. was accompanied by the production of free ammonia (18), and the recovery of free ammonia and six amino acids in the exudates of incubated and sulfur-dusted fruits (18). 

Denitrification can be affected by free ammonia, but this inhibition does not appear up to 300 to 400 mg/L NH3.46 This high concentration can justify that no inhibition of the denitrification process has been reported for this kind of wastewater.3-4 Eiroa and colleagues37 observed that nitrate was eliminated much faster at higher initial urea concentrations. However, they also found an increase of nitrite accumulation, which was later removed, due to high urea concentrations. 

Kohczkowski, A. et al., J. Chem. Technol. Biotechnol., 1981, 31, 327-332 Depending on the conditions, presence of free ammonia in ammonium nitrate may either stabilise, or tend to destabilise, the salt. 

Melam hydrobromide undergoes thermal degradation between 450-550 0 (2nd step, Figure 6) with complete elimination of bromine either through evolution of ammonium bromide, which is the major product, or melamine hydrobromide as shown by IR. Also a small amount of free ammonia is evolved in this step in which melon is formed as shown by the IR of the residue at 550 0 (ca. 35% of original melamine hydrobromide). 

Nessler cylinder 1 pair Ferric ammonium sulphate 1.726 g Sulphuric acid (0. 1 N) 10.0 ml Iron-free citric acid (20% w/v) 2.0 ml Thioglycollic acid 0.1 ml Iron-free ammonia solution 20 ml. 

Standard Colour Dilute 2.0 ml of standard iron solution with 40 ml DW in a Nessler cylinder. Add 2 ml of a 20% w/v solution of iron-free citric acid and 0.1 ml of thioglycollic acid, mix, make alkaline with iron-free ammonia solution, dilute to 50 ml with DW and allow to stand for 5 minutes. 

The effect of concentration of free (molecular) ammonia on the activity of the electrolyte was derived mainly from two 80 C data points of Miles and Wilson having 16 to 17 molal free ammonia concentration. Data points below 0.2 ionic strength were fitted by application of Kielland s estimation of ionic activity coefficients(6 2). Details are presented elsewhere(45), together with graphs giving partial pressures of ammonia and hydrogen sulfide for temperatures from 80 to 260 F over a range of liquid concentration. 

The dissociation correction was applied by dividing the uncorrected volatility ratio by the computed ratio of free ammonia over total ammonia in solution. The ratio of free ammonia over total ammonia was computed from the dissociation constant of ammonia given by Edwards and Prausnitz (1 ) as follows. 

With no other ions present the concentration of free ammonia over total ammonia present is given by the following equation ... 

Cnh3 = concentration of free ammonia, moles/Kg water... 

Thus the last column in Tables 1 and 2 corresponds to the volatility ratio of ammonia based on free ammonia and extrapolated to zero concentration of free ammonia. This number should be independent of the concentrations studied at a given temperature, and... 

Note also that ammonium sulfate is absent from the recommended binding buffer formulations despite its general popularity in the field. Ammonium ions become fully titrated at alkaline pH and convert to ammonia gas. Buffer pH may become unstable as a result and causticity of the free ammonia may partially hydrolyze the proteins in a sample, creating a source of assay variability.617 18 At small buffer volumes used for analytical applications, liberated ammonia gas may not be a significant health hazard, but precautions may still be necessary to meet regulations. For all these reasons, ammonium salts are best avoided at alkaline pH. 

This has obvious advantages over the process seen for glutamate synthesis via the reductive amination of 2-oxoglutarate, in that it no longer requires the intervention of free ammonia. We thus have the situation that some organisms are able to carry out the fixation of ammonia via reductive amination, whereas others manipulate via transamination the amino acid structures obtained from protein in the diet. 

Table 21.2 lists all important direct application materials and their percentage of direct application fertilizers. Direct application use is increasing mainly because of anhydrous ammonia gas becoming popular. It can be pumped in 3-6 in. beneath the soil during plowing and is absorbed by the soil rapidly. Nitrogen solutions can also be applied in this manner (mixture of free ammonia, ammonium nitrate, urea, and water). 

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