Brominated Methanes as Photoresponsive Molecular Storage of Elemental Br₂

Abstract

The photochemical generation of elemental Br2 from brominated methanes is reported. Br2 was generated by the vaporization of carbon oxides and HBr through oxidative photodecomposition of brominated methanes under a 20 W low‐pressure mercury lamp, wherein the amount and situations of Br2 generation were photochemically controllable. Liquid CH2Br2 can be used not only as an organic solvent but also for the photoresponsive molecular storage of Br2, which is of great technical benefit in a variety of organic syntheses and in materials science. By taking advantage of the in situ generation of Br2 from the organic solvent itself, many organobromine compounds were synthesized in high practical yields with or without the addition of a catalyst. Herein, Br2 that was generated by the photodecomposition of CH2Br2 retained its reactivity in solution to undergo essentially the same reactions as those that were carried out with solutions of Br2 dissolved in CH2Br2 that were prepared without photoirradiation. Furthermore, HBr, which was generated during the course of the photodecomposition of CH2Br2, was also available for the substitution of the OH group for the Br group and for the preparation of the HBr salts of amines. Furthermore, the photochemical generation of Br2 from CH2Br2 was available for the area‐selective photochemical bleaching of natural colored plants, such as red rose petals, wherein Br2 that was generated photochemically from CH2Br2 was painted onto the petal to cause radical oxidations of the chromophoric anthocyanin molecules.

Thiourea-Mediated Halogenation of Alcohols

“…1-Bromoadamantane (2ze). 62 Reaction time: 10 h; obtained as a white solid (152 mg, yield = 72%). 1 H NMR (400 MHz, CDCl 3 ) δ 2.40 (d, J = 4 Hz, 6H), 2.90 (bs, 3H), 1.72 (t, J = 4H, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ 49.3, 36.5, 33.…”

Tunable Photocatalytic Two-Electron Shuttle between Paired Redox Sites on Halide Perovskite Nanocrystals

“…To verify which route is correct, we add CsPbBr 3 and DIPEA into DBM and stir the mixture under light irradiation for 3 h. After that, 1,3,5-trimethoxybenzene is added and the mixture is stirred in the dark for 2 h. Interestingly, the corresponding bromination product (1a) is obtained (Figure 3c). The results show that the photocatalytic system generates larger amounts of elemental Br 2 form DBM, a promising bromine candidate, 35 via reduction−oxidation cascade on the CsPbBr 3 NC surface.…”

Employing Aryl‐Linked Bis‐mesoionic Carbenes as a Pincer‐Type Platform to Access Ambient‐Stable Palladium(IV) Complexes

“…Furthermore,n oB rsubstituted product was observed, while such halogenated alkene species was found in Kraftsc ase.I nterestingly,w hen trans-stilbene was used as the olefin substrate,t he reaction gave an intractable product mixture including 6,b ut no corresponding vicinal dibromide was observed as indicated by 1 HNMR spectroscopy. [19] Considering that trans-stilbene is known to be facilely brominated by Br 2 ,weproposed that the bromine transfer in the current case might not involve adirect BrÀBr reductive elimination followed by Br 2 -bromination of the olefin. However,t he mechanism remains to be further elucidated in the future.…”