Application of 108-47-4, Because a catalyst decreases the height of the energy barrier, its presence increases the reaction rates of both the forward and the reverse reactions by the same amount.108-47-4, Name is 2,4-Dimethylpyridine, molecular formula is C7H9N. In a article£¬once mentioned of 108-47-4
Metal coordination by sterically hindered heterocyclic ligands, including 2-vinylpyridine, assessed by investigation of cobaloximes
Structural and 1H NMR data have been obtained for cobaloximes with the bulkiest substituted pyridines reported so far. We have isolated in noncoordinating solvents the complexes CH3Co(DH)2L (methylcobaloxime, where DH = the monoanion of dimethylglyoxime) with L = sterically hindered N-donor ligands: quinoline, 4-CH3quinoline, 2,4-(CH3)2pyridine, and 2-R-pyridine (R = CH3, OCH3, CH2CH3, CH=CH2). We have found that the Co-Nax bond is very long in the structurally characterized complexes. In particular, CH3Co(DH)2(4-CH 3quinoline) has a longer Co-Nax bond (2.193(3) A) than any reported for methylcobaloximes. The main cause of the long bonds is unambiguously identified as the steric bulk of L by the fairly linear relationship found for Co-Nax distance vs CCA (calculated cone angle, CCA, a computed measure of bulk) over an extensive series of methylcobaloximes. The linear relationship improves if L basicity (quantified by pKa) is taken into account. In anhydrous CDCl3 at 25C, all complexes except the 2-aminopyridine adduct exhibit 1H NMR spectra consistent with partial dissociation of L to form the methylcobaloxime dimer. 1H NMR experiments at -20C allowed us to assess qualitatively the relative binding ability of L as follows: 2,4-(CH3)2pyridine > 4-CH3quinoline ? quinoline ? 2-CH3pyridine > 2-CH3Opyridine > 2-CH3CH2pyridine > 2-CH2=CHpyridine. The broadness of the 1H NMR signals at 25C suggests a similar order for the ligand exchange rate. The lack of dissociation by 2-aminopyridine is attributed to an intramolecular hydrogen bond between the NH2 group and an oxime O atom. The weaker than expected binding of 2-vinylpyridine relative to the Co-Nax bond length is attributed to rotation of the 2-vinyl group required for this bulky ligand to bind to the metal center, a conclusion supported by pronounced changes in 2-vinylpyridine signals upon coordination.
A reaction mechanism is the microscopic path by which reactants are transformed into products. Each step is an elementary reaction. In my other articles, you can also check out more blogs about 108-47-4
Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis