Catalysts allow a reaction to proceed via a pathway that has a lower activation energy than the uncatalyzed reaction. , Recommanded Product: 1-Bromo-4-iodobenzene, 589-87-7, Name is 1-Bromo-4-iodobenzene, molecular formula is C6H4BrI, belongs to thiomorpholine compound. In a document, author is Shi, TS, introduce the new discover.
Structure-reactivity correlations for complex formation reactions between square-planar metal centers and thioethers
Kinetics for complex formation between Pd(H2O)(4)(2+) and thioethers of largely varying electronic and steric properties, viz. MeSCH(2)COOH, (n-Pr)(2)S, EtSCH(2)CH(2)OH, S(CH2CH2CH2OH)(2), S(CH2CH2OH)(2), EtSCH(2)COOH, S(CH2COOH)(2), S(CH2CH2COOH)(2), (i-Pr)(2)S, (s-Bu)(2)S, (t-Bu)(2)S, and protonated thiomorpholine, S(C2H4)(2)NH2+, has been studied by use of stopped-flow spectrophotometry in an acidic aqueous medium. Second-order rate constants k(1)(298) are 1.61 x 10(4), 8.0 x 10(4), 3.79 x 10(4), 3.69 x 10(4), 2.21 x 10(4), 1.84 x 10(4), 1.91 x 10(3), 1.34 x 10(4), 1.52 x 10(4), 7.75 x 10(3), 900, and 5.2 x 10(3) M(-1) s(-1), respectively. The reactivity toward Pd(H2O)(4)(2+) of all thioethers studied so far can be described as a function of their sigma-donor properties as expressed by the sum of the Taft constants, Sigma sigma*, and their steric requirements as defined by cone angles, theta, by use of the equation: log k(1) = (9.9 +/- 0.3) – (0.67 +/- 0.05)Sigma sigma* – (0.059 +/- 0.003)theta. Similarly, second-order rate constants k(298) reported previously for reactions between thioethers and Pd(dien)H2O2+ and Pt(dienBr+ are described by log k(298) = (10.5 +/- 0.6) – 0.67 Sigma sigma* – (0.081 +/- 0.006)theta and log k(298) = (4.6 +/- 0.6) – 0.72 Sigma sigma* – (0.080 +/- 0.006)theta, respectively. Hence, the reactivity trends of thioethers toward square-planar complexes can be given a general interpretation in terms of intrinsic, electronic, and steric parameters, by use of log k = gamma + alpha Sigma sigma* + beta theta. Large variations in both electronic and steric properties of the entering ligands indicate that there is no ”duality behavior” in the reactions of thioethers with square-planar metal centers, as claimed in previous literature. No steric threshold is observed for these sterically unhindered systems. There is a rough compensation effect between Delta H-1 double dagger and Delta S-1 double dagger, i.e. a smaller Delta H-1 double dagger is usually accompanied by a larger negative Delta S-1 double dagger, indicating that all thioethers react via the same mechanism. It appears that the much lower reactivity observed for the highly branched (t-Bu)(2)S is primarily caused by a high activation enthalpy. Volumes of activation have been determined for a series of thioethers with a constant cone angle, viz. EtSCH(2)COOH, S(CH2COOH)(2), and S(CH2CH2COOH)(2) through high-pressure stopped-flow measurements. Values of Delta V-1 double dagger are -7.9 +/- 0.5, -8.1 +/- 0.4, and -7.6 +/- 0.3 cm(3) mol(-1), respectively. These values together with that for Et(2)S (-8.7 +/- 0.1 cm(3) mol(-1)) determined previously shows that variation of electronic properties, steric factors being kept constant, change the reactivity markedly, but have no observable influence on the activation volumes. Stability constants beta(1) for five palladium thioether complexes derived as the ratio between rate constants for forward and reverse reactions vary between (1.2 +/- 0.3) x 10(4) and (3.2 +/- 0. 7) x 10(4) M(-1).
Recommanded Product: 1-Bromo-4-iodobenzene, The reactant in an enzyme-catalyzed reaction is called a substrate. Enzyme inhibitors cause a decrease in the reaction rate of an enzyme-catalyzed reaction.I hope my blog about 589-87-7 is helpful to your research.
Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem