Ammonia thermodynamic balance

Cremer, H. Thermodynamic balance and analysis of syngas and ammonia plant. ACS Symposium Series, Vol. 122, ASME Washington, DC, 1980. 

Cremer, H., "Thermodynamic Balance and Analysis of a Synthesis Gas and Ammonia Plant", Thermodynamics Second Law Analysis, A.C.S. Symposium Series, 122, 111-120, 1980. 

Thermodynamic Balance and Analysis of a Synthesis Gas and Ammonia Plant... 

The delicate balance between adduct formation at position 2 or at position 4 is shown in the amino-dehydrogenation of 4-methoxy-5-nitropyrimidine. The course of the amination is found to temperature dependent. Treatment with liquid ammonia/permanganate at —60° to —70 °C gave 2-amino-4-methoxy-5-nitropyrimidine, while at +20 °C 6-amino-4-methoxy-5-nitropyrimidine is obtained (Scheme 18) (83JOC1354). This result indicates that at low temperature the C-2 adduct is the kinetically favored one and at room temperature the C-4 adduct is thermodynamically favored. 

From the preceding discussions it is evident that at least four different temperatures have to be considered which under laboratory conditions are all equal the excitation temperature Tex of the molecule, defined by the relative populations of the levels, the kinetic temperature Tk, corresponding to the Maxwellian velocity distribution of the gas particles, the radiation temperature Traa, assuming a (in some cases diluted) black body radiation distribution, and the grain temperature 7, . With no thermodynamic equilibrium established, as is common in interstellar space, none of these temperatures are equal. These non-equilibium conditions are likely to be caused in part by the delicate balance between the various mechanisms of excitation and de-excitation of molecular energy levels by particle collisions and radiative transitions, and in part by the molecule formation process itself. Table 7 summarizes some of the known distribution anomalies. The non-equilibrium between para- and ortho-ammonia, the very low temperature of formaldehyde, and the interstellar OH and H20 masers are some of the more spectacular examples. 

---