Why does aibn decompose so easily




















The taming of cyclobutadiene. Article Google Scholar. Warmuth, R. Jr A self-assembled cylindrical capsule: new supramolecular phenomena through encapsulation. Article PubMed Google Scholar. Ziegler, M. Stabilization of a reactive cationic species by supramolecular encapsulation. Cavity-directed synthesis of labile silanol oligomers within self-assembled coordination cages. Dong, V. Molecular recognition and stabilization of iminium ions in water.

Iwasawa, T. Jr Stabilization of labile carbonyl addition intermediates by a synthetic receptor. Science , — Mal, P. White phosphorus is air-stable within a self-assembled tetrahedral capsule. Nishimura, N. Self-assembled boronic ester cavitand capsule as a photosensitizer and a guard nanocontainer against photochemical reactions of 2,6-diacetoxyanthracene.

Horiuchi, S. Noncovalent trapping and stabilization of dinuclear ruthenium complexes within a coordination cage. Fetzer, J. Watson, M. Sheppard, C. Moad, G. The Chemistry of Radical Polymerization Elsevier Kishi, N. An M2L4 molecular capsule with an anthracene shell: encapsulation of large guests up to 1nm. Molecular architectures of multi-anthracene assemblies.

Kita, Y. Tetrahedron Lett. Sun, C. Theoretical study on the thermal decomposition of azoisobutyronitrile. Kleywegt, G. Detection, delineation, measurement and display of cavities in macromolecular structures. D 50 , — Ajami, D. Jr More chemistry in small spaces.

Ko, Y. U-shaped conformation of alkyl chains bound to a synthetic host. Choudhury, R. Hydrocarbons depending on the chain length and head group adopt different conformations within a water-soluble nanocapsule: 1 H NMR and molecular dynamics studies. B , — Facile catch and release of fullerenes using a photoresponsive molecular tube.

Download references. Klosterman Bowling Green State University for helpful discussions. You can also search for this author in PubMed Google Scholar. All authors discussed the results and commented on the manuscript. Correspondence to Michito Yoshizawa. Reprints and Permissions. Yamashina, M. Nat Commun 5, Download citation. Received : 12 April Accepted : 10 July Published : 18 August Anyone you share the following link with will be able to read this content:.

Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Nature Reviews Chemistry Nature Nanotechnology Nature Communications By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Advanced search. Skip to main content Thank you for visiting nature.

Download PDF. Subjects Nanoscale materials Organic chemistry. Abstract 2,2'-Azobisisobutyronitrile and its derivatives are standard reagents for polymer and organic syntheses that generate radical species on stimuli by light or heat. You have full access to this article via your institution. Introduction Intrinsic properties of molecules can be altered on encapsulation within artificial or biological nanospaces 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8.

Figure 1: Structure of a supramolecular nanocapsule and radical initiators. Full size image. Results Encapsulation of AIBN by capsule 1 Supramolecular capsule 1 spontaneously encapsulated one molecule of AIBN by hydrophobic interactions and the resultant inclusion complex was confirmed by nuclear magnetic resonance NMR , mass spectrometry MS and X-ray crystallographic analyses.

Figure 5: Schematic representation of olefin polymerization with capsule 1 containing a radial initiator. Discussion In this study, we successfully controlled the stabilities of well-known and widely used radical initiators, AIBN and its derivatives, toward light through encapsulation within a supramolecular nanocapsule with polyaromatic frameworks.

Additional information Accession codes: CCDC and contain the supplementary crystallographic data for the structures reported in this article. Another way of describing the constraints placed on the desired sequence in Scheme 6 by an additional propagation step is in terms of chain-transfer reactions. In each propagation sequence the chain-transfer step ends the existing cycle and creates the radical that begins a new cycle.

In the reactions shown in Scheme 6 the third step in the desired sequence and the second step in the diverting sequence are the chain-transfer steps for their respective reactions.

Radical addition cannot be successful if the rate of the chain-transfer step in the diverting sequence is greater than the rate of the radical-transforming step i. Analysis of the reaction shown in Scheme 6 can be done in a more quantitative manner using the rate constants shown in Scheme 7 and the information given in eq The first step in the formation of any product in this reaction is bromine-atom abstraction by the tri- n -butyltin radical eq Equations are found in Scheme 7.

Radical philicity and its effect on radical reactivity are discussed in Chapter 7. There are some situations in which solvent effects are significant in radical reactions. Any process that stops the participation of a radical in a propagation sequence terminates the reaction chain. Forming a peroxy radical by reaction with oxygen not only terminates a desired propagation sequence, but it also creates a reactive radical that is capable of becoming part of a different reaction sequence. Roger W.

Binkley Cleveland Heights-University Heights school system. The Initiation Phase 1. Thermal Initiators a. Photochemical Initiation Photochemical initiation requires a compound to absorb a photon of light and then use this energy to cleave a bond homolytically and, in so doing, create an initiating radical or radicals.

Hexaalkylditins The chain-carrying radical in many reactions of carbohydrates is the tri- n -butyltin radical 8. The Propagation Phase 1. Examples of Propagation Sequences The basic characteristics of a propagation sequence can be seen by examining two specific reactions. Rate Constants and Reaction Rates Analysis of the reaction shown in Scheme 6 can be done in a more quantitative manner using the rate constants shown in Scheme 7 and the information given in eq



0コメント

  • 1000 / 1000