89284-69-5

Upstream product

• 824-69-1 2,5-dichloro-1,4-hydroquinone 
• 2138-22-9 4-chloro-1,2-benzenediol 
• 143810-02-0 tetraethyl (3,6-dichloro-1,4-benzoquinone-2,5-diyl)dimalonate 
• 106-48-9 4-chloro-phenol 

Downstream Products

• 119290-91-4 5-chloro-2-hydroxy-p-hydroquinone 

Relevant academic research and scientific papers

A combined experimental and computational investigation on the unusual molecular mechanism of the lossen rearrangement reaction activated by carcinogenic halogenated quinones

The classic Lossen rearrangement is a wellknown reaction describing the transformation of an Oactivated hydroxamic acid into the corresponding isocyanate. In this study, we found that chlorinated benzoquinones (CnBQ) serve as a new class of agents for the activation of benzohydroxamic acid (BHA), leading to Lossen rearrangement. Compared to the classic one, this new kind of CnBQ-activated Lossen rearrangement has the following unique characteristics: (1) The stability of CnBQ-activated BHA intermediates was found to depend not only on the degree but also on the position of Cl-substitution on CnBQs, which can be divided into two subgroups. (2) It is the relative energy of the anionic CnBQ-BHA intermediates that determine the rate of this CnBQ-activated rearrangement, which is the rate-limiting step, and the Cl or H ortho to the reaction site at CnBQ is crucial for the stability of the anionic intermediates. (3) A pKa-activation energy correlation was observed, which can explain why the correlation exists between the rate of the rearrangement and the acidity of the conjugate acid of the anionic leaving group, the hydroxlated quinones. These findings may have broad implications for future research on halogenated quinoid carcinogens and hydroxamate biomedical agents.

Characterization of chlorophenol 4-monooxygenase (TftD) and NADH:FAD oxidoreductase (TftC) of burkholderia cepacia AC1100

Burkholderia cepacia AC1100 completely degrades 2,4,5-trichlorophenol, in which an FADH2-dependent monooxygenase (TftD) and an NADH:FAD oxidoreductase (TftC) catalyze the initial steps. TftD oxidizes 2,4,5-trichlorophenol (2,4,5-TCP) to 2,5-dichloro-p-benzoquinone, which is chemically reduced to 2,5-dichloro-p-hydroquinone (2,5-DiCHQ). Then, TftD oxidizes the latter to 5-chloro-2-hydroxy-p-benzoquinone. In those processes, TftC provides all the required FADH2. We have determined the crystal structures of dimeric TftC and tetrameric TftD at 2.0 and 2.5 A resolution, respectively. The structure of TftC was similar to those of related flavin reductases. The stacked nicotinamide:isoalloxazine rings in TftC and sequential reaction kinetics suggest that the reduced FAD leaves TftC after NADH oxidation. The structure of TftD was also similar to the known structures of FADH2-dependent monooxygenases. Its His-289 residue in the re-side of the isoalloxazine ring is within hydrogen bonding distance with a hydroxyl group of 2,5-Di-CHQ.AnH289Amutation resulted in the complete loss of activity toward 2,5-DiCHQ and a significant decrease in catalytic efficiency toward 2,4,5-TCP. Thus, His-289 plays different roles in the catalysis of 2,4,5-TCP and 2,5-DiCHQ. The results support that free FADH2 is generated by TftC, and TftD uses FADH2 to separately transform 2,4,5-TCP and 2,5-DiCHQ. Additional experimental data also support the diffusion of FADH2 between TftC and TftD without direct physical interaction between the two enzymes.

Photocatalytic degradation of 4-chlorophenol. 2. The 4-chlorocatechol pathway

The TiO2-mediated photocatalytic degradation of 4-chlorocatechol is studied as a branch of the degradation of 4-chlorophenol. In addition to some basic kinetic studies, the identities of many of the cyclic and acyclic intermediates, verified in most cases with authentic samples, are reported. From 4-chlorocatechol, the major product is hydroxylation to form 5-chloro- 1,2,4-benzenetriol. A small amount of 4-chloropyrogallol is also produced. Substitution to give 1,2,4-benzenetriol is observed as is oxidative cleavage of the C1-C2 bond to give the diacid. The major products of all of the triols are those of oxidative cleavages, occurring mainly between ortho hydroxy- substituted carbons to give diacids but also between one hydroxy and one unsubstituted carbon to give acid-aldehydes. Many smaller intermediates in the degradations are identified, and pathways are proposed for the larger compounds.