961-39-7Relevant articles and documents
U(SMes*)n, (n = 3, 4) and Ln(SMes*)3 (Ln = La, Ce, Pr, Nd): Lanthanide(III)/actinide(III) differentiation in agostic interactions and an unprecedented η3 ligation mode of the arylthiolate ligand, from X-ray diffraction and
Roger, Mathieu,Barros, Noemi,Arliguie, Therese,Thuery, Pierre,Maron, Laurent,Ephritikhine, Michel
, p. 8790 - 8802 (2007/10/03)
Reaction of U(NEt2)4 with HS-2,4,6- tBu3C6H2 (HSMes*) gave U(SMes*)3(NEt2)(py) (1), whereas similar treatment of U[N(SiMe3)SiMe2CH2][N
Formation by SRN1 reactions and 1H N.M.R. properties of sterically encumbered 2,4,6-triaIkyIphenyl p-nitrobenzyl sulfides
Look, Kai,Norris, Robert K.
, p. 1077 - 1083 (2007/10/03)
Sterically hindered p-nitrobenzylic chlorides (1) and (2) react with the sodium salts of 2,4,6-trialkylbenzenethiols (3a)-(5a) by the SRN1 reaction to give good yields of the corresponding p-nitrobenzylic aryl sulfides (6)-(10). For example, th
The Markedly Enhanced Basicity of Selenenamides vs Sulfenamides and the Mechanism of the Methanolysis of o-Nitro- and 2,4,6-Tri-tert-butylbenzeneselenenamides
Kice, John L.,Kutateladze, Andrei G.
, p. 917 - 923 (2007/10/02)
Measurement in acetonitrile-methanol of the basicity of selenenamides shows that they are approximately 3 pK units more basic than the corresponding sulfenamides.Since other explanations do not seem tenable, this apparently results from the fact that selenium is less electronegative than sulfur, although it is somewhat surprising that the small difference in the electronegativity of the two elements should lead to such a large difference in basicity.In the same solvent the kinetics of the acid-catalyzed methanolyses (eq 2) of o-nitro- and 2,4,6-tri-tert-butylbenzeneselenenamides are similar (large dependence of rate on , unusual dependence of rate on +>) to those for the methanolysis of the corresponding o-nitrobenzenesulfenamides.In the latter case the kinetics have been shown to be indicative of a mechanism where a sulfuranide (3, eq 5) is the key intermediate on the reaction coordinate; as a consequence, a similar kind of mechanism (eq 6) involving a hypervalent selenium intermediate (4) is proposed for eq 2.The unusual dependence on +> is because acid-catalyzed reversion of 4 to protonated selenenamide (2-H+) and methanol (step k-6) is faster under certain conditions than cleavage of 4 to give the final products (step k7).Comparison of the methanolysis kinetics of o-nitro (2a) and 2,4,6-tri-tert-butylbenzeneselenenamides (2c) shows that the coordination of an o-nitro group to selenium that stabilizes 2a and 2a-H+ does not appear to change the mechanism for methanolysis although it does cause the partitioning of 4 (k-6+>/k7) to be much less favorable to the formation of products (step k7).
Chemistry of Sulfenic Acids. 3. Studies of Sterically Hindered Sulfenic Acids Using Flash Vacuum Pyrolysis
Davis, Franklin A.,Jenkins, Robert H.,Rizvi, Syed Q. A.,Yocklovich, Steven G.
, p. 3467 - 3474 (2007/10/02)
Flash vacuum pyrolysis (FVP) of sulfoxides containing β-hydrogen atoms affords sulfenic acids (RSOH) in good concentration under conditions where they are stable.The application of this technique to the synthesis and study of sterically hindered sulfenic acids 12a-e is described.The principal or primary reaction of simple sulfenic acids prepared in this manner is dehydration to thiosulfinates 13 (eq 1).Steric inhibition to dehydration (eq 1) appears to only be of importance for 2-methyl-2-propanesulfenic acid (12a) which was trapped in good yield with methyl propiolate to afford 16a. 2,4,6-Tri-tert-butylbenzenesulfenic acid (12e) appears to be destabilized as a consequence of interaction between the SOH and adjacent tert-butyl groups.In the pyrolysis section of the apparatus, 12e decomposes to phenol 21 and aryl radical 22, which reacts further.Thermolysis of sulfoxides generates the sulfenic acids 12a-e in very low concentration at any one time.The products of sulfenic acids generated in this way result from secondary reactions of the corresponding thiosulfinates.
