2.5- Dichloro-l,4-benzoquinone

Chemical/Physical. An aqueous solution containing chloramine reacted with 2,4,6-tri-chlorophenol to yield the following intermediate products after 2 h at 25 °C 2,6-dichloro-l,4-benzoquinone-4-(A-chloro)imine and 4,6-dichloro-l,2-benzoquinone-2-(A-chloro)imine (Maeda et al., 1987). 

Qin F, Zhao YY, Zhao Y, Boyd JM, Zhou W, Li XF (2010) A toxic disinfection by-product, 2,6-dichloro-l,4-benzoquinone, identified in drinking water. Angew Chem Int Ed 49(4) 790-792... 

The kinetics and mechanism of the reactions of trialkyl phosphites with mucochloric acid (dichloroaldehydoacrylic acid) have been studied.6 Cine-substitution products are formed in reactions of 2,5- and 2,6-dichloro-l,4-benzoquinone with pyrrolidine.7... 

The kinetics of oxidation of aldehydes by the Fenton reagent [Fe(II)-H202-0H-] have been studied.89 It has been suggested that different reactivities of PhIO in iron(III)-porphyrin-catalysed alkene epoxidation may be due to the formation of a more reactive iron(IV)-0-IPh complex.90 The iron(m) complex of tetrakis(3,5-disulfonato-mesityl)porphyrin catalyses the oxidative degradation of 2,4,6-trichlorophenol to 2,6-dichloro-l,4-benzoquinone with KHSO5 as the oxygen atom donor a peroxidase-type oxidation is thought to be involved.91... 

The kinetics and mechanism of the reactions of trialkyl phosphites with mucochloric acid (dichloroaldehydoacrylic acid) have been studied. Cine-substitution products are formed in reactions of 2,5- and 2,6-dichloro-l,4-benzoquinone with pyrrohdineJ The reaction of vinyl fluoride with CN has been studied by the DFT B3YLP/6-31- -G(d) method. This nucleophilic substitution is mainly a n attack with a barrier height of 14.8kcalmol , which is 17.91 kcalmoC more favovuable than the a attack. 

The reaction enthalpies for the photo-reduction of ketones and azoalkanes in n,ji states by the model hydrogen donors methanol and dimethylamine have been calculated. These data, together with a consideration of excited-state electrophilicity and the antibonding character of transition states, have been used to rationalize the nucleophilic character of singlet n,ji excited azoalkanes and the electrophilic character of correspondingly excited ketones. A theoretical model for the photo-reduction of carbonyl compounds, based on the assumption that hydrogen transfer involves electron transfer followed by proton transfer, has been developed. The model was able to describe the available kinetic data for the photo-reduction of o-benzoquinones and fluorenone in the presence of para substituted iV,iV-dimethylanilines and those for the photo-reduction of p-chloro-anil and 2,6-dichloro-l,4-benzoquinones in the presence of polymethylben-zenes. The photochemical properties of the triplet ji, n state of 5,12-naph-... 

Vilar and coworkers [59] have investigated the use of additives to suppress olefin migration in the self-metathesis of urea derivatives (Scheme 12.33). The Af-allyl urea 109 was found to undergo self-metathesis in the presence of Ru catalyst 3 in 33% yield. The isomerized species 110 was isolated as the major product (55% yield, Z= 1 1). Vilar and coworkers identified phenylphosphoric acid (112) as an effective inhibitor of the undesired alkene isomerization. When the metathesis of Af-allyl urea 109 was performed with phenylphosphoric acid (50mol%), the desired dimer 111 was isolated in 56% yield, and 30% of the starting material 109 could be recovered. The authors also investigated the use of benzoquinone derivatives, and found that 2,6-dichloro-l,4-benzoquinone (10 mol%) was equally... 

In 2007, Cossy and coworkers [61] demonstrated that small-molecule additives could be used to help inhibit olefin migration in challenging CM reactions (Scheme 12.35). Investigating the CM of lactone 117 with olefin 118 by H-NMR, the desired product 119 was formed in 50% yield, while a 13% yield of the isomerized lactone (120) was formed. A variety of small-molecule additives (5mol%) were then studied to suppress the undesired olefin isomerization. While a number of phosphorous-derived additives were surveyed, two additives clearly stood out as being the most efficient 2,6-dichloro-l,4-benzoquinone and -chlorocatechol. In particular, the 2,6-dichloro-l,4-benzoquinone was able to... 

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