1013-92-9Relevant academic research and scientific papers
Synthesis of Novel Representatives of Phosphoryl Guanidine Oligonucleotides
Zhukov,Pyshnyi,Kupryushkin
, p. 380 - 389 (2021/05/03)
Abstract: Novel representatives of phosphoryl guanidine oligonucleotide derivatives were prepared in this study. A synthetic scheme has been proposed and implemented suitable for the preparation of a wide range of diaminocarbenium azides starting from various secondary amines for subsequent incorporation of tetrasubstituted guanidine residues into the oligonucleotides by the Staudinger reaction. A number of factors which affected the yield of the phosphoryl guanidine derivative were identified, in particular, the size of the alkyl substituents in the azide used, the purity of the azide, and the conditions for elimination of the protecting cyanoethyl group before the final deprotection of the oligonucleotide.
Steric and Repeated-collision Effects in Diffusion-controlled Reactions in Solution: Kinetics of Formation of some Iodine Donor-Acceptor Complexes of Sulphur Compounds
Caldin, Edward F.,Forest, L. de,Queen, Alan
, p. 1549 - 1554 (2007/10/02)
Rates of formation of electron donor-electron acceptor complexes of iodine with some compounds of the general formula R2CS with iodine (R2CS...I-I) in 1-chlorobutane have been determined by means of a microwave temperature-jump apparatus.For each of these reactions, the observed forward rate constant (kf) is proportional to the theoretical diffusion-controlled value (k*D) over a range of temperatures, but somewhat smaller.The values of kf/k*D for the various reactions are approximately inversely proportional to the estimated surface areas of the R2CSmolecules.Assuming that the area of the reactive site is constant, this suggests that kf/k*D is proportional to the fraction of the molecule surface area that is reactive, i.e. that kf is subject to a geometrical steric factor.The obsered values of kf/k*D are, however, ca. four times larger than would be expected on this basis from molecular models, if one took into account only the frequency with which first-time collisions occur between reactant molecules with the correct orientation.This discrepancy can be removed by taking into account the fact that repeated collisions during an encounter will increase the chance of a successful collision.A hard-sphere model of encounters between molecules with limited reaction sites, reorienting by rotation between collisions, suggests that repeated collisions may contribute to kf/k*D a factor in the region of 4, in line with our experimental results.
