Kinetics melting point

For liquids that are reasonably fluid around their melting points, the kinetic factors in Eq. DC-15 come out about 10 /cm sec, so that Eq. IX-15 becomes... 

Isomerization. Maleic acid is isomerized to fumaric acid by thermal treatment and a variety of catalytic species. Isomerization occurs above the 130 to 140°C melting point range for maleic acid but below 230°C, at which point fumaric acid is dehydrated to maleic anhydride. Derivatives of maleic acid can also be isomerized. Kinetic data are available for both the uncatalyzed (73) and thiourea catalyzed (74) isomerizations of the cis to trans diacids. These data suggest that neither carbonium ion nor succinate intermediates are involved in the isomerization. Rather, conjugate addition imparts sufficient single bond character to afford rotation about the central C—C bond of the diacid (75). 

The decomposition kinetics of an organic peroxide, as judged by 10-h HLT, largely determines the suitabiUty of a particular peroxide initiator in an end use appHcation (22). Other important factors ate melting point, solubiUty, cost, safety, efficiency, necessity for refrigerated storage and shipment, compatibihty with production systems, effects on the finished product, and potential for activation. 

Imidazole, 4-methyl-annular tautomerism, 5, 363 association, 5, 362 boiling point, 5, 362 bromination, 5, 398 deuteration, 5, 417 diazo coupling, 5, 403 hydrogen bonding, S, 350 hydroxymethylation, 5, 404 iodination, 5, 400 kinetics, 5, 401 mass spectra, 5, 358 melting point, 5, 362 methylation, 5, 364 sulfonation, 5, 397 synthesis, 5, 479-480, 482, 484, 489 Imidazole, 5-methyl-annular tautomerism, 5, 363 Imidazole, l-methyl-4-chloro-ethylation, 5, 386 Imidazole, l-methyl-5-chloro-ethylation, 5, 386 nitration, 5, 395... 

For the reaction KCIO4 -t- 2C KCl -t- CO2, fine powders were compressed to 69 MPa (10,000 psi) and reacted at 350°C (662°F), well Below the 500°C (932°F) melting point. The kinetic data were fitted by the equation... 

However, the reaction rate of LiA.Cn depends on the lithium concentration at the surface of the carbon particles, which is limited by the rather slow transport kinetics of lithium from the bulk to the surface LI7-19, 39]. As the melting point of metallic lithium is low (-180 °C) there is some risk of melting of lithium under abuse conditions such as short-circuiting, followed by a sudden breakdown of the SEI and a violent reaction of liquid lithium... 

The melting point Tm and kinetics are independent of pH and of the salt concentration. This was found by studies in 1% aqueous acetic acid, pH 3.0 as well as in 50 mM phosphate buffer, pH 7.5). Recently, Greiche and Heidemann23 described the synthesis... 

Lindemann <8> has made an interesting application of the new theory in the determination of the frequency of atomic vibration, r, from the melting-point. He assumes that at the melting-point, T the atoms perform vibrations of such amplitude that they mutually collide, and then transfer kinetic energy like the molecules of a gas. The mean kinetic energy of the atom will then increase by RT when the liquid is unpolymerised and the fusion occurs at constant volume this is the molecular heat of fusion. 

PBTP was depolymerised in excess methanol under high temperature (473-523 K) and high pressure (4-14 MPa) conditions. Depolymerisation was earried out at 483 K and 4-12 MPa, and at 513 K and 6-14 MPa. The temperature had a great effect on the depolymerisation rate, but the reaction pressure did not. Under the former eonditions, depolymerisation took over 80 min, but only about 20 min under the latter eonditions. The se results showed that the supereritieal state of methanol was not a key faetor in the depolymerisation reaction. A kinetic study of the reaetion at 473-523 K and 12 MPa showed that the deeomposition rate eonstant of PBTP increased dramatieally when the reaetion temperature was higher than the melting point of PBTP (500 K). This indicated that partial miseibility of the molten PBTP and methanol was an important faetor for the short-time depolymerisation. 9 refs. 

The copper remaining in lead after the above operation is removed by matte formation. Finely divided sulfur is added to molten lead at temperatures slightly above its melting point, and the melt is stirred continuously. Copper sulfide forms and floats on the surface, leaving the bullion substantially free of copper (less than 0.005%). The standard free energies of formation of cuprous sulfide and lead sulfide are about the same the observed separation must, therefore, be due to kinetic factors or to the influence of certain minor impurities that are present in the lead. 

Sulfathiazole has been found to crystallize in three distinct polymorphic forms, all of which are kinetically stable in the solid state but two of which are unstable in contact with water [130]. As evident in Fig. 20, the initial intrinsic dissolution rates are different, but as forms I and II convert into form III, the dissolved concentrations converge. Only the dissolution rate of form III was constant during the studies, indicating it to be the thermodynamically stable form at room temperature. Aqueous suspensions of forms I or II were all found to convert into form III over time, supporting the finding of the dissolution studies. Interestingly, around the melting points of the three polymorphs, form I exhibited... 

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