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Apparent second-order rate constants (k(n)(app)) for the nucleophilic reaction of aniline (Ani) with phthalic anhydride (PAn) vary from 6.30 to 7.56 M(-1) s(-1) with the increase of temperature from 30 to 50 degrees C in pure glacial acetic acid (AcOH). However, the values of pseudo-first-order rate constants (k(s)) for the acetolysis of PAn in pure AcOH increase from 16.5 x 10(-4) to 10.7 x 10(-3) s(-1) with the increase of temperature from 30 to 50 degrees C. The values of k(n)(app) and k(s) vary from 5.84 to 7.56 M(-1) s(-1) and from 35.1 x 10(-4) to 12.4 x 10(-4) s(-1), respectively, with the increase of CH(3)CN content from 1% to 80% v/v in mixed AcOH solvents at 35 degrees C. The plot of k(s) versus CH(3)CN content shows a minimum (with 10(4) k(s) = 4.40 s(-1)) at 50% v/v CH(3)CN. Similarly, the variations of k(n)(app) and k(s) with the increasing content of tetrahydrofuran (THF) in mixed AcOH solvent reveal respective a maximum (with k(n)(app) = 17.5-15.6 M(-1) s(-1)) at 40-60% v/v THF and a minimum (with k(s) = approximately 0-1.2 x 10(-4) s (-1)) at 60-70% v/v THF. The respective values of DeltaH* and DeltaS* are 15.3 +/- 1.2 kcal mol(-1) and -20.1 +/- 3.8 cal K(-1) mol(-1) for k(s) and 1.1 +/- 0.5 kcal mol(-1) and -51.2 +/- 1.7 cal K(-1) mol(-1) for k(n)(app), while the values of k(n) (= k(n)(app)/f(b) with f(b) representing the fraction of free aniline base) are almost independent of temperature within the range 30-50 degrees C. A spectrophotometric approach has been described to determine f(b) in AcOH as well as mixed AcOH-CH(3)CN and AcOH-THF solvents. Thus, the observed data, obtained under different reaction conditions, have been explained quantitatively. An optimum reaction condition, within the domain of present reaction conditions, has been suggested for the maximum yield of the desired product, N-phenylphthalamic acid. 相似文献
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A kinetic study on hydrolysis of N‐(2′‐hydroxyphenyl)phthalamic acid ( 1 ), N‐(2′‐methoxyphenyl)phthalamic acid ( 2 ), and N‐(2′‐methoxyphenyl)benzamide ( 3 ) under a highly alkaline medium gives second‐order rate constants, kOH, for the reactions of HO? with 1, 2 , and 3 as (4.73 ± 0.36) × 10?8 at 35°C, (2.42 ± 0.28) × 10?6 and (5.94 ± 0.23) × 10?5 M?1 s?1 at 65°C, respectively. Similar values of kOH for 3 , N‐methylbenzanilide, N‐methylbenzamide, and N,N‐dimethylbenzamide despite the difference between pKa values of aniline and ammonia of ~10 pK units are qualitatively explained. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 1–11, 2009 相似文献
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Ionics - We have tailored the extraction solvent of natural anthocyanin pigments from Ixora coccinea flower to lower charge transport resistance and enhance effective electron diffusion coefficient... 相似文献
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Emmy Fadhiza Damit Nor Saadah M. Yusof Azhar Ariffin M. Niyaz Khan 《Journal of the Iranian Chemical Society》2012,9(5):723-727
The values of pseudo-first-order rate constants (k obs) for the acetolysis of phthalic anhydride (PAn) increase from 6.60?×?10?7 to 31.5?×?10?7?s?1 with the increase in temperature from 30 to 50?°C. These values of k obs give activation parameters ?H* and ?S* as 14.4?±?0.4?kcal?mol?1 and ?39.1?±?1.3?cal?K?1?mol?1, respectively. The values of k obs remain essentially unchanged with the increase in the content of CS (CS?=?CH3CN or THF) from 0 to 40?% v/v in mixed AcOH?CCS solvents. These observations have been explained qualitatively. 相似文献
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