Ammonia experimental results

Turning now to the experimental data, we find that the mobility of the (NH4)+ ion in liquid ammonia does not have any high value that would indicate a contribution from proton jumps.1 Nor docs the (CH,0) ion in methanol or the (C2H5O)- ion in ethanol solution.2 These experimental data do not force us to accept the Hiickel mechanism but if we do not accept the mechanism, we shall have to make some ad hoc assumptions to explain these experimental results. 

This paper also reported results for three permanent dipole molecules, HC1, H20, and NH3, which exhibited an energy dependence of the specific rate constant in this energy range. The data for ammonia are typical and are presented in Figure 7. The points are experimental results,... 

Figure 3.29 Ammonia oxidation over a Pt catalyst in different membrane micro reactors. Experimental results show good temperature uniformity across the catalyst regions [19].

When a A = 1849 A light acts on an ammonia molecule, the latter breaks into a hydrogen atom and an NH2 radical [13]. At the zinc oxide surface the former particle is an electron donor, whereas the latter one is an acceptor. Experiments indicate that in photolysis of ammonia in a vessel shown in Fig. 4.6. only hydrogen atoms can be detected at every level of the vessel, starting from the source. This experimental result can be accounted for by the fact that, even in presence of such acceptors as... 

Other studies conducted on mixed protonated clusters of ammonia bound with TMA showed that the ion intensity distributions of (NH3)n(TMA)mH+191 display local maxima at (n,m) = (1,4), (2,3), (2,6), (3,2), and (3,8). Observation that the maximum ion intensity occurs at (n,m) = (1,4), (2,3), and (3,2) indicates that a solvation shell is formed around the NHJ ion with four ligands of any combination of ammonia and TMA molecules. In the situation where the maximum of the ion intensity occurs at (n,m) = (2,6) and (3,8), the experimental results suggest that another solvation shell forms which contains the core ions [H3N-H-NH3]+ (with six available hydrogen-bonding sites) and [H3N-H(NH2)H-NH3]+ (with eight available hydrogen-bonding sites). The observed metastable unimolecular decomposition processes support the above solvation model. 

Arthur L. Weber (1998), now working at the Seti Institute of the Ames Research Center at Moffett Field, reports the successful synthesis of amino acid thioesters from formose substrates (formaldehyde and glycolaldehyde) and ammonia synthesis of alanine and homoserine was possible when thiol catalysts were added to the reaction mixture. On the basis of his experimental results, Weber (1998) suggests the process shown in Fig. 7.10 to be a general prebiotic route to amino acid thioesters. 

NH3-CO2-H2O are compared with calculated results in figures 2 and 3 and in tables I to IV. At temperatures between 20 and 60 oc partial pressures of ammonia calculated from different methods agree well with each other there is also a good agreement with experimental results by van Krevelen et al. (J ) (cf. table I) and Pexton and Badger (J 2) (cf. table II). For molalities mtot,NH3 and mtot,C02 eviations amount to... 

System NH -S02 H20 For comparison with calculated data only the experimental results of Johnstone (16) and Boublik et al. (JT 1 ) were used. (Boublik et al. investigated the system NH3-SO2-SO3-H2O only some of their results with very low SO3/SO2 ratios were used for comparison with calculated data). Experimental results by other authors mostly cover very high solute concentrations in the liquid phase (20 molal and more) and are, therefore, not suitable for comparison with the models discussed here. As van Krevelen s method cannot be used for this system, the comparison is limited to the other procedures. Partial pressures of ammonia calculated from the BR-model are generally too large the calculated values exceed the experimental results mostly by a factor larger than 5. The EMNP method generally yields partial pressures which are only about half as large as the measured ones. The calculated partial pressures of SO2 are always too small, for temperatures between 50 and 90 °C the mean deviations a-mount from 20 to 40 per cent for the EMNP-model and from 40 to 70 per cent for the BR-model. 

The first drawback is the evolution of ammonia (NH ) as a transient gas during the reaction of (3.27b) [128, 130, 131, 133, 135, 137, 138, 140, 141]. Hu and Ruckenstein [141] were the first to clearly point out that NH is formed through the decomposition of LiNH but is quickly captured by LiH. After careful analysis of all available experimental results Ichikawa et al. [130, 131,138] proposed that the reaction of (3.27b) progresses with the involvement of the following two elementary sub-reactions which are essential for its completion... 

It has been established that the conversion of 2-chloro-4-phenylquinazo-line into 2-amino-4-phenylquinazoline by treatment with potassium amide/liquid ammonia also occurs with ring opening (74RTC227).This was proved by the experimental result that in the 2-amino compound obtained from 2-chloro-4-phenyl[3- N]quinazoline, about 70% of the label is present in the amino group, i.e., formation of 2-[ N-amino]-4-phenylquina-zoline (83) see Scheme 11.36. 

Experiment 4. Rates of Formation of Ethylenediamine and Ammonia vs. Rate of Appearance of Cobalt (II). Tris-N-hydroxyethylethylenediamine cobalt-(III) chloride (6) (0.020 mole) was placed in the reaction flask with 100 ml. of water, 45.80 grams of N-hydroxyethylethylenediamine, and 2.5 grams of activated carbon, and the reaction was carried out as in Experiment 3. The experimental results are shown in Figure 4. 

A first validation was obtained simulating the results collected at different ammonia to NOx feed ratios as an example, in Fig. 43 some of the experimental results (symbols) are compared with the model predictions (line). 

The reduction of these compounds would give mole of labelled aniline, H moles of ordinary aniline, i mole of labelled ammonia and mole of ordinary ammonia, which is incompatible with the experimental results actually obtained. 

There is some evidence that cation and radical are not generated independently. If cation and radical are formed separately, inhibition of one active species will not influence the reactivity of other. The experimental results suggest the interrelation of cation and radical. For example, the addition of ammonia inhibits the cationic process, whereas the yield of radical polymerization even increases. Also, the content of... 

It is, however, not clear at present whether such a model can be applied to metal solutions. It is worth mentioning again at this point that the specific conductivity of a saturated solution of lithium in methyl-amine (10) (concentration 5.5M) has been found to be 28 ohm l cm."-1, which is two orders of magnitude lower than that for a corresponding saturated metal-ammonia solution. This experimental result seems to indicate that the overlap between electron trapping centers may not be... 

A complete interpretation of these experimental results must account for differences in the photoregeneration reaction in ethylamine compared with ammonia. These include the different spectra of the flash transients and their relation to the stable metal species, the appearance of two decay stages of the flash intermediate in ammonia instead of one very slow decay in ethylamine, the irreversible appearance... 

Report of the experimental procedure and the experimental results obtained is given in F. Haber and R. LeRossignol, On the Ammonia-Equilibrium , Ber. Bunsenges. Phys. Chem., 40, 2144-2154 (1907). The report of the final results is found in F. Haber and R. LeRossignol, The Ammonia Equilibrium under Pressure , Z. Elektrochem. 14, 181-196 (1908). 

Stewart and Hack (5.) have presented operating characteristics of pressure swing adsorption systems for reducing impurities in a hydrogen stream from 40 vol percent to 1 ppm. Impurities included ammonia, water, methane, carbon monoxide, carbon dioxide, nitrogen, and several hydrocarbons. In this study heatless adsorption is used to separate hydrogen sulfide-hydrogen mixtures and the experimental results are compared with theoretical models. 

On the basis of the experimental results mentioned in the last section, a plausible mechanism for TCRT using aromatic ketone and ammonium acetate is proposed in Scheme 14. Since ammonium acetate is not nucleophilic, the TCRT proceeds in a somewhat different pathway from that using ammonia, as shown in Scheme 12. 

In stereochemical experiments, it cannot be decided whether the planar form, attained via pyramidal inversion of the chiral intermediates (Scheme 13, first line), is a transition state or an intermediate. By calculation (116, 117), however, it can be shown that 16-electron systems of the type C8H8Mn(CO)2, in contrast to the planar structures of such 18-electron systems as C8H8Co(CO)2, are pyramidal, like ammonia, with a barrier to inversion. This barrier should be higher for an acyl substituent than for an ester substituent, in agreement with the experimental results (117). 

Novel microreactors with immobilized enzymes were fabricated using both silicon and polymer-based microfabrication techniques. The effectiveness of these reactors was examined along with their behavior over time. Urease enzyme was successfully incorporated into microchannels of a polymeric matrix of polydimethylsiloxane and through layer-bylayer self-assembly techniques onto silicon. The fabricated microchannels had cross-sectional dimensions ranging from tens to hundreds of micrometers in width and height. The experimental results for continuous-flow microreactors are reported for the conversion of urea to ammonia by urease enzyme. Urea conversions of >90% were observed. 

The results of an experimental Investigation are presented for the separation of mixtures of 1,3-butadiene and 1-butene at near critical conditions with mixed and single solvent gases. Ammonia was used as an entrainer to enhance the separation. Several non-polar solvents were used which included ethylene, ethane and carbon dioxide, as well as mixtures of each of these gases with ammonia in concentrations of 2, 5, 8 and 10% by volume. Each solvent and solvent mixture was studied with respect to its ability to remove 1-butene from an equimolar mixture of 1,3-butadiene/ 1-butene. Maximum selectivities of 1.4 to 1.8 were measured at a pressure of 600 psia and a temperature of 20 C in mixtures containing 5%-8% by volume of ammonia in ethylene. All other solvents showed little or no success in promoting separation of the mixture. The experimental results are reported for ethylene/ ammonia mixtures and are shown to be in fair agreement with VLE flash calculations predicted independently by a modified two parameter R-K type of equation of state. 

We have applied some of these principles to the extraction of 1-butene from a binary mixture of 1,3-butadiene/1-butene. Various mixtures of sc solvents (e.g., ethane, carbon dioxide, ethylene) are used in combination with a strongly polar solvent gas like ammonia. The physical properties of these components are shown in Table I. The experimental results were then compared with VLE predictions using a newly developed equation of state (18). The key feature of this equation is a new set of mixing rules based on statistical mechanical arguments. We have been able to demonstrate its agreement with a number of binary and ternary systems described in the literature, containing various hydrocarbon compounds, a number of selected polar compounds and a supercritical component. 

A series of experiments was conducted to determine whether there exists an ammonia concentration for which maximum separation could be attained. At a pressure of 600 psia and 20 degrees C. and between 5 and 8 vol% ammonia, a maximum in the selectivity is obtained and is shown in Fig. 4. The selectivity, however, decreases with increasing temperature, with other variables held constant as shown in Fig. 5. The trend observed these experiments are in agreement with the findings of Brignole, et al.(19). An error of +/- 5% was estimated in the calculation of the experimental selectivities. The experimental results were compared with predictions obtained from the equation of state, assuming that the interaction parameter, k - 0.2 for ammonia and 1-butene dominated the non-ideality of the system. A comparison of the calculated selectivities obtained for the ethylene/ammonia mixtures are given in Table II with the results in Table III for the ethane system. 

The results of these calculations are summarized in Table II. Formal charges predict that all nitroquinolines should have their highest reactivity at C-2. This is not confirmed by the experimental results. By comparing the experimental results with the FMO calculations it became evident that the order of reactivity of the ammonia addition is in good agreement. Thus, the addition reaction is orbital-controlled (87JOC5643). 

---