Noyes’ relationship

In order to estimate high-temperature rate constants, it is necessary to establish the kinetic behaviour of reactions over as wide a temperature range as possible. Modelling is very important to show what physics or chemistry is missing, to test experimental uncertainties, and to provide a view outside the window of experimental observation. Alteration of the physical and chemical properties of water upon heating (see section 15.2) makes kinetic analysis of reacting systems rather complex. A convenient method for extrapolation of the kinetic data is provided by the Noyes relationship. ... 

Modelling calculations with the Noyes relationship have proved that up to 523 K (250 °C) the kinetic data for elementary radical reactions in water are well reproduced with temperature-independent encounter parameters, and with approximated by ... 

Table 15.1 Parameters for modelling rates of elementary radical reaction by the Noyes relationship (eqn (15.1)).

Figure 15.13 Effect of temperature on the rate constant of reaction H + OH - H2O modelled by the Noyes relationship (eqn (15.1)) (solid line). A satisfactory agreement with experimental values ( ) " provides the test for the barrierless chemical step.

Also, hydrates are more soluble in water-miscible solvents than are the corresponding anhydrous forms. For example, the solubility of caffeine hydrate is lower than that of anhydrous caffeine in water but higher in ethanol. The maximum concentration seen may be due to the solubility of the anhydrous crystalline phase or due to a temporary steady state in which the rate of dissolution of the metastable anhydrous form and the rate of crystallization of the stable hydrate are equal. The decreasing concentration represents crystallization of the stable hydrate from a solution supersaturated with respect to it. If the maximum concentration of the solute in the dissolution experiment corresponds to the solubility, then the initial increase in concentration follows the Noyes-Whitney equation [15]. Van t Hoff plots of log solubility versus the reciprocal of temperature give linear relationships (Fig. 16). 

The relationship between surface area and dissolution rate is described by the Noyes-Whitney equation,... 

Multifunctional organics are also possible contributors. Nielsen et al. (1998) have examined the possible contribution of multifunctional compounds to missing NOy in both the gas and particle phases. As discussed in Chapter 9, compounds with sufficiently high vapor pressures (> 2x 10 5 Torr) exist essentially completely in the gas phase, those with low vapor pressures (< 2 X 10 9 Torr) in the condensed phase (i.e., on or in particles), and those in between the two extremes as both gases and particles. Nielsen and co-workers have developed a relationship between the expected vapor... 

This relationship is based on data for 183 compounds, including C7-C2y hydrocarbons, C,-Cls alcohols, C2-C10 diols, C5-C1X carbonyls, C1-C20 alkyl nitrates, and C2-C3 hydroxynitrates and dinitrates. Based on this analysis, Nielsen et al. (1998) suggest that the organic nitrates found in particles are probably bi- and multifunctional compounds and that they may also contribute to gas-phase NOy and NOz. 

Figure 11. Relationship between NOy and N20 in the polar stratosphere. The curves are labeled with the potential temperatures the lower potential temperatures correspond to lower altitudes and, in these cases, lower absolute temperatures. (Reproduced with permission from reference 85. Copyright 1990 Macmillan Magazines Ltd.)...

This equation is an approximation to the relationship given by Noyes (1961). 

SOURCE Reprinted with permission from Noy, A., C.H. Sanders, D.V. Vezenov, S.S. Wond, and C.M. Lieber. 1998. Chemically sensitive imaging in tapping mode by chemical force microscopy Relationship between phase lag and adhesion, Langmuir 14 1508-1511. Copyright 1998 American Chemical Society. 

Natural product synthesis and medicinal chemistry exist in a symbiotic relationship with the development of synthesis methodology. Noy-ori s asymmetric hydrogenations, Sharpless olefin oxidations, Grubbs olefin metathesis, Buchwald-Hartwig couplings and Jacobsen s hydrolytic kinetic resolution are illustrious examples with many practical applications. The key to the success of the above-mentioned reactions is that they have provided reliable shortcuts to more traditional synthetic... 

RELATIONSHIPS OF NDRC PERSONNEL TO THE ARMED FORCES [Noyes, pages 141-152]. 

The relationship between NDRC on the one hand and the Army and Navy on the other constitutes one of the most important phases on the history of the scientific effort of the United States from 1940 to 1946. Many mistakes were made and at times there was much bitterness. . . Many NDRC representatives were irked by the long lapse of time between the inception of an idea and use of a developed item in Theaters of Operations. [Noyes, page 141]. 

As might be expected, relationships were good or bad depending on the personalities of the individuals involved. [Noyes, page 152],... 

According to Murad, the value of l/Q varies linearily with the acetaldehyde pressure at 3340 A. Parmenter and Noyes , however, pointed out that 2/ is independent of the acetaldehyde pressure at this wavelength, claiming that it is only the triplet emission for which a linear relationship holds. The plot of [CHsCHOJ/gy versus [CH3CHO] results in an approximately straight line at 3130 A. 

It is clear from Figure 9.16 that aspirin absorption is more rapid from solution than from tablet formulations. This rapid absorption of aspirin is an indication that the rate of absorption is dissolution rate limited. A general relationship describing the dissolution of a drug was first reported by Noyes and Whitney (38). The equation derived by those authors is as follows ... 

However, it is less well known why men of science abandoned their commitments to intemationality and communality - values which, while often honoured more in the breach than the observance, had served usefully in the conduct of European science for over a century. Indisputably, scientists became crusaders, overtaking political and military leaders in their zeal to apply science to the war effort. Nowhere was this feature so pronounced as in chemistry. In the United States, a new willingness on the part of scientists nourished a scientific-military-industrial complex, linked to special relationships among the Allies, that has continued to the present day. For Arthur Noyes and other chemists, the war was the first taste of work that was deemed of demonstrable and immediate importance to the general community, and their first experience in spending money freely. As a consequence, chemistry, interwoven with... 

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