32024-13-8Relevant academic research and scientific papers
Studies of the triplet state of the proton-transfer tautomer in salicylaldehydes
Chou, Pi-Tai,Chiou, Chau-Shuen,Yu, Wei-Shan,Wu, Guo-Ray,Wei, Tai-Huei
, p. 747 - 755 (2003)
The spectroscopy and dynamics of the low-lying triplet state of the proton-transfer tautomer in salicylaldehydes have been studied via internal heavy-atom effects coupled with a sensitive near-IR detecting system. For 3,5-diiodosalicylaldehyde a weak proton-transfer keto-tautomer phosphorescence was resolved with a maximum at 710 nm (τp ～ 1.8 μs, φobs ～ 5.23 × 10-4) in a 77 K methylcyclohexane glass. The results, in combination with the time-resolved thermal lensing experiment, further deduced the triplet-state population yield and radiative decay rate to be 0.20 (298 K) and 3.12 × 102 s-1, respectively. Consequently, the energetics and dynamics of the triplet states during a proton transfer cycle are discussed in detail.
Catalysis and regioselectivity of the aqueous Heck reaction by Pd(0) nanoparticles under ultrasonic irradiation
Zhang, Zuhui,Zha, Zhenggen,Gan, Changsheng,Pan, Chongfeng,Zhou, Yuqing,Wang, Zhiyong,Zhou, Ming-Ming
, p. 4339 - 4342 (2007/10/03)
An aqueous Heck reaction carried out under ultrasonic irradiation at the ambient temperature (25 °C) has been shown in this study to afford high yields of corresponding products. It was found that as a catalyst for the reaction palladium forms nanoparticles in-situ, characterized by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analyses, and can be recycled. Furthermore, the Heck reaction under such mild and environmentally friendly conditions offers excellent regioselectivity of para-over ortho-substitution in phenyl iodides especially with electron-donating groups.
Iodination of Methylated Anisoles: Unusual Aryl Methyl Replacement and Oxidations
Panetta, Charles A.,Fang, Zheng,Mattern, Daniell L.
, p. 7953 - 7958 (2007/10/03)
The treatment of methylated anisoles with iodine, periodic acid, sulfuric acid, and aqueous acetic acid has resulted in iododemethylations and/or aryl methyl oxidations in addition to the expected mono- and diiodinations of the aromatic ring.Four dimethylanisoles and o-methylanisole were treated under identical conditions.Iododemethylations were observed in three of the four dimethylanisoles and aryl methyl oxidations to benzaldehydes occured with o-methylanisole and two of the dimethylanisoles.No precedence could be found for either of these reactions under the experimental conditions employed.Several possible mechanisms are discussed for these transformations.Some experimental evidence suggests that methyl oxidation to a benzaldehyde could be a prerequisite for an iododemethylation via an iodonium ion-assisted reverse Gatterman-Koch reaction; single-electron-transfer or classical electrophilic mechanisms are also consistent with the iododemethylations.
