Thermal induced atomization

Keywords Contact angle Corona splashes Disintegration Disintegration limits Droplet impact Drop surface energy Heat transfer regimes Leidenfrost point Molten metal droplet impact Rupture Secondary atomization Spread Surface topography Thermal induced atomization Wettability... 

Fig. 7.10 Ni Mossbauer spectra of LaNi5 samples after various treatments (a) no hydrogen exposure, (b) activated in hydrogen, (c) after 1,584 thermally induced absorption-desorption cycles, as described in the text. The solid lines are least-squares fits to a single Lorentzian in (a) and (b). (c) was fitted with a single Lorentzian (representing nonmagnetic nickel atoms) and a 12-line hyperfine spectrum (from [20])...

Transformations through 1,2-addition to a formal PN double bond within the delocalized rc-electron system have been reported for the benzo-l,3,2-diazaphospholes 5 which are readily produced by thermally induced depolymerization of tetramers 6 [13] (Scheme 2). The monomers react further with mono- or difunctional acyl chlorides to give 2-chloro-l,3,2-diazaphospholenes with exocyclic amide functionalities at one nitrogen atom [34], Similar reactions of 6 with methyl triflate were found to proceed even at room temperature to give l-methyl-3-alkyl-benzo-l,3,2-diazaphospholenium triflates [35, 36], The reported butyl halide elimination from NHP precursor 13 to generate 1,3,2-diazaphosphole 14 upon heating to 250°C and the subsequent amine addition to furnish 15 (Scheme 5) illustrates another example of the reversibility of addition-elimination reactions [37],... 

Diazocarbonyl compounds readily undergo [3 + 2] cycloaddition to electron-poor alkenes 139). The 1-pyrazolines thus formed usually tautomerize to 2-pyrazolines if there is a hydrogen in an a-position to one of the nitrogen atoms otherwise, thermally induced ring contraction with evolution of nitrogen to give cyclopropanes can occur (Scheme 18). 

The discussion above has been directed principally to thermally induced spin transitions, but other physical perturbations can either initiate or modify a spin transition. The effect of a change in the external pressure has been widely studied and is treated in detail in Chap. 22. The normal effect of an increase in pressure is to stabilise the low spin state, i.e. to increase the transition temperature. This can be understood in terms of the volume reduction which accompanies the high spin—dow spin change, arising primarily from the shorter metal-donor atom distances in the low spin form. An increase in pressure effectively increases the separation between the zero point energies of the low spin and high spin states by the work term PAV. The application of pressure can in fact induce a transition in a HS system for which a thermal transition does not occur. This applies in complex systems, e.g. in [Fe (phen)2Cl2] [158] and also in the simple binary compounds iron(II) oxide [159] and iron(II) sulfide [160]. Transitions such as those in these simple binary systems can be expected in minerals of iron and other first transition series metals in the deep mantle and core of the earth. 

Doppler broadening, caused by the thermally induced movement of atoms relative to the spectrometer. (This is analogous to the apparent change in pitch of a train whistle as it approaches and passes an observer.)... 

Although the initiation step under purely thermally induced conditions such as those imposed by shocks has not been formulated, it is expected to be a reaction that produces O atoms. The high-temperature mechanism would then be reactions (8.105), and (8.124)-(8.126), with termination by the elimination of the O atoms. 

The thermally induced cyclization of A -(benzyloxycarbonyl)phenyl ketenimines 415, obtained in a two-step, one-pot procedure from benzyl 2-azidobenzoates 414, led to 2-substituted-4/f-3,l-benzoxazin-4-ones 416 (Scheme 79). The reaction involves the formation of a new carbon-oxygen bond and migration of the benzyl group from the oxygen atom to the terminal carbon atom of the ketenimine fragment <2005S2426>. 

Although evidence for thermally induced migrations points to a sigmatropic shift of the substituent, as discussed above, the photochemical conversion of 2-cyanopyrrole into 3-cyanopyrrole proceeds by a [1,3] sigmatropic walk of the heteroannular atom by route (a), as shown in Scheme 2. 2-Cyano-3-methylpyrrole and 2-cyano-4-methylpyrrole undergo similar phototranspositions to produce 3-cyano-4-methylpyrrole (by route a) and 4-cyano-2-methylpyrrole (by route a), respectively (75CC786), whilst 2-cyano-5-methylpyrrole produces... 

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