503-28-6Relevant articles and documents
Light-enabled metal-free pinacol coupling by hydrazine
Qiu, Zihang,Pham, Hanh D. M.,Li, Jianbin,Li, Chen-Chen,Castillo-Pazos, Durbis J.,Khaliullin, Rustam Z.,Li, Chao-Jun
, p. 10937 - 10943 (2019/12/23)
Efficient carbon-carbon bond formation is of great importance in modern organic synthetic chemistry. The pinacol coupling discovered over a century ago is still one of the most efficient coupling reactions to build the C-C bond in one step. However, traditional pinacol coupling often requires over-stoichiometric amounts of active metals as reductants, causing long-lasting metal waste issues and sustainability concerns. A great scientific challenge is to design a metal-free approach to the pinacol coupling reaction. Herein, we describe a light-driven pinacol coupling protocol without use of any metals, but with N2H4, used as a clean non-metallic hydrogen-atom-transfer (HAT) reductant. In this transformation, only traceless non-toxic N2 and H2 gases were produced as by-products with a relatively broad aromatic ketone scope and good functional group tolerance. A combined experimental and computational investigation of the mechanism suggests that this novel pinacol coupling reaction proceeds via a HAT process between photo-excited ketone and N2H4, instead of the common single-electron-transfer (SET) process for metal reductants.
Quantitative Studies of Methyl Radicals Reacting with Metal Oxides
Xu, Mingting,Ballinger, Todd H.,Lunsford, Jack H.
, p. 14494 - 14499 (2007/10/02)
The reactive sticking coefficients of CH3. radicals, produced by the thermal decomposition of azomethane, were determined over ZnO, CeO2, La2O3, Sr/La2O3, and Li/MgO at 650 deg C.The intrinsic sticking coefficients ranged from 6*10-8 for La2O3 activated at 900 deg C to 3*10-5 over ZnO.In the presence of even o.1 mTorr of O2 the sticking coefficient for the La2O3 sample increased to 3*1006.Although the other nonreducible oxides exhibited similar behaviours, the magnitude of the effect was not as great.Methyl radicals are believed to react via electron transfer at the surface.The electron transfer may be either to metal ions, in the case of reducible oxides, or to O2, in the case of nonreducible oxides.Reactions of CH3. radicals with several high surface area, porous silicas and zeolites were also studied.The sticking coefficient on a high-purity silica was found to be 1*10-8 at 200 deg C.An analysis of the stable products indicated that the reaction of CH3. radicals with these surfaces exceeded the coupling reactions that might have occured at the surfaces.That is, the surfaces did not function as an effective "third body" in the coupling reaction.
1-Thia-3,4-diazolidine-2,5-dione Functionality: A Photochemical Synthon for the Azo Group
Squillacote, Michael,Felippis, James De
, p. 3564 - 3571 (2007/10/02)
The 1-thia-3,4-diazolidine-2,5-dione functional group was shown to yield azo compounds upon photolysis.This photoreaction when combined with the known ability of this group to react in a Diels-Alder fashion or as a dinucleophile toward alkylating agents greatly increases the utility of this functionality.The dual reactivity of this group was demonstrated in the synthesis of a number of 3,4-dialkyl-1-thia-3,4-diazolodone-2,5-diones.The photolysis of these compounds produced either thermally stable cyclic azo compounds or the decomposition products of thermally unstable azo compounds.
