65076-96-2

Upstream product

• 96-76-4 2,4-di-tert-Butylphenol 
• 1138-52-9 3,5-Di-tert-butylphenol 
• 1020-31-1 3,5-Di-tert-butylcatechol 

Relevant academic research and scientific papers

Determining the TiO2-photocatalytic aryl-ring-opening mechanism in aqueous solution using oxygen-18 labeled O2 and H2O

The molecules O2 and H2O dominate the cleavage of aromatic sp2 C-C bonds, a crucial step in the degradation of aromatic pollutants in aqueous TiO2 photocatalysis, but their precise roles in this process have remained elusive. This can be attributed to the complex oxidative species involved and to a lack of available models for reactions with a high yield of direct products. Here, we used oxygen-18 isotope labeled O 2 and H2O to observe the aromatic ring-opening reaction of the model compound 3,5-di-tert-butylcatechol (DTBC), which was mediated by TiO2 photocatalysis in an aqueous acetonitrile solution. By analyzing the primary intermediate products (～75% yield), especially the seven-membered ring anhydrides that were formed, we obtained direct evidence for the oxygen atom of dioxygen insertion into a C-C bond of the aromatic ring. This indicates that molecular oxygen is the ultimate ring-opening agent in TiO2 photocatalysis and that it undergoes single O atom incorporation rather than the previously proposed molecular oxygen 1,2-addition processes. The ratio of intradiol to extradiol products depends on the particle size of TiO2 catalysts used, which suggests that the O2 activation is correlated with the available coordination sites on the TiO2 surface in the photocatalytic cleavage of the aromatic ring.

A novel pentadentate redox-active ligand and its iron(III) complexes: Electronic structures and O2 reactivity

A novel redox-active ligand, H4Ph2SLAP (1) which was designed to be potentially pentadentate with an O,N,S,N,O donor set is described. Treatment of 1 with two equivalents of potassium hydride gave access to octametallic precursor complex [H2Ph2SL APK2(thf)]4 (2), which reacted with FeCl 3 to yield iron(III) complex [H2Ph2SL APFeCl] (3). Employing Fe[N(SiMe3)2] 3 for a direct reaction with 1 led to ligand rearrangement through C-S bond cleavage and thiolate formation, finally yielding [HLAPFe] (5). Upon exposure to O2, 3 and 5 are oxidized through formal hydrogen-atom abstraction from the ligand NH units to form [ Ph2SLSQFeCl] (4) and [LSQFe] (6) featuring two or one coordinated iminosemiquinone moieties, respectively. Moessbauer measurements demonstrated that the iron centers remain in their +III oxidation states. Compounds 3 and 5 were tested with respect to their potential as models for the catechol dioxygenase. Thus, they were treated with 3,5-di-tert-butyl- catechol, triethylamine and O2. It turned out that the iron-catecholate complexes react with O2 in dichloromethane at ambient conditions through C-C bond cleavage mainly forming extradiol cleavage products. Intradiol products are only side products and quinone formation becomes negligible. This observation has been rationalized by a dissociation of two donor functions upon coordination of the catecholate. A radical convention: A novel pentadentate O,N,S,N,O ligand system, LH4, which is redox active, has been developed, so that its iron(III) complex (H2LFeCl) reacts with O2. H atoms are abstracted from the NH units present so that the ligand is converted into a diradical, featuring two iminosemiquinonato moieties that clamp a high-spin iron(III) center. The complex proved capable of mimicking catechol dioxygenase reactivity, and mediates extradiol cleavage with remarkable selectivity.

The formation of orthoquinones in the dimethyldioxirane oxidation of phenols

The dimethyldioxirane oxidation of selected phenols provides the corresponding orthoquinones. This conversion proceeds via the related arenediols, which are cleanly oxidized to the quinones by this oxidant.