Mononitration of phenol derivatives by guanidinium nitrate and silica sulfuric acid under mild conditions

A mixture of guanidinium nitrate and silica sulfuric acid acts as mild and heterogeneous media for the efficient mono nitration of phenolic compounds in dichloromethane at room temperature.     

Novel synthesis of a unique helical quinone derivative by coupling reaction of 2-hydroxybenzo[c]phenanthrene

Oxidative coupling reaction of both 3-hydroxychrysene and 2-hydroxybenzo[c]phenanthrene by using Cu(NO₃)₂-3H₂O under atmospheric air is described. The former gave the aimed coupled biaryl derivative. However, the latter gave a further oxidized helical quinone derivative. The unique helical structure was characterized by X-ray and NMR analysis.     

间接法测定工业废水中微量苯酚

研究了用吸光光度法间接测定微量苯酚的方法。在KBrO3和KBr溶液中,以淀粉 碘化钾为显色剂,最大吸收波长为590nm,线性范围为0.10～2.00mg·L-1,回收率为92%～110%,NH+4、Ca2+、Fe3+等不干扰测定。该法用于测定工业废水中痕量苯酚,结果满意。     

Wettability modification of pitch-based spherical activated carbon by air oxidation and its effects on phenol adsorption

The surface chemistry of pitch-based spherical activated carbon (PSAC) was modified by air oxidation to enhance its wettability as well as adsorption properties. Changes of PSAC after modification in texture, surface chemistry and wettability were studied by different techniques including N₂ adsorption, X-ray photoelectron spectroscopy (XPS) and dynamic contact angle analyzer (DCA). Phenol adsorption characteristics in different solvents on PSAC were also investigated. When PSAC was modified under an atmosphere with 20 vol.% oxygen at 400 and 450 °C for 5 h, surface acidic groups increased from 0.11 to 1.22 and 1.60 meq/g, while basic groups decreased from 0.52 to 0.03 and 0.02 meq/g, respectively. After PSAC was modified, the increase of the oxygen-containing groups, especially carboxylic and phenolic ones, is responsible for the increasing of the surface acidity and the significant improvement of the wettability of PSAC. PSAC with a relatively high oxygen content provided a low adsorption capacity to phenol in aqueous solution, and the adsorption isotherms change from Langmuir class (L) to the S-shaped curve; while the solvent is changed into cyclohexane, all adsorption isotherms are type L, and the adsorption capacity to phenol increases with increasing oxygen-containing groups. Possible reasons, including the solvent effect, π-π dispersion and donor-acceptor interactions are discussed.     

Cellulose as recyclable organocatalyst for ipso-hydroxylation of arylboronic acids

Cellulose catalyzed oxidative hydroxylation of aryl and hetero-arylboronic acids to the corresponding phenols under metal and base free strategy has been demonstrated. The sustainable ipso-hydroxylation takes place using hydrogen peroxide as an oxidant in water under mild condition in shorter period of time. Interestingly, easy recovery and reusability of heterogeneous catalyst without significant loss in catalytic yield makes the protocol environmentally benign.     

Mechanism of N-to-S acyl transfer of N-(2-hydroxybenzyl) cysteine derivatives and origin of phenol acceleration effect

The mechanism of N-to-S acyl transfer of N-(2-hydroxybenzyl) cysteine derivatives and the origin of acceleration effect of phenol substitutes were investigated by DFT methods.     

Attempt to Synthesize Hindered 2,4,6‐Tri‐Aryloxy‐s‐Triazines: Bis(2,4‐di‐tert‐Butylphenyl) Carbonate – Crystal Structure

Some less hindered 2,4,6‐tri‐aryloxy‐s‐triazines were synthesized through the reaction of the corresponding phenols as a starting materials with cyanogen bromide (BrCN) to obtain the corresponding arylcyanates and then trimerized. Unexpectedly, 2,4‐di‐tert‐butyl‐1‐cyanatobenzene derived from 2,4‐di‐tert‐butylphenol did not trimerize but, indeed, yielded bis(2,4‐di‐tert‐butylphenyl) carbonate. The structures of 2,4,6‐tri‐aryloxy‐s‐triazines and bis(2,4‐di‐tert‐butylphenyl) carbonate were characterized by means of IR, ¹H, and ¹³C NMR spectroscopies. Also the structure of the latter compound was studied by X‐ray crystallography.     

Photodecomposition of phenol in a flow reactor: Adsorption and kinetics

Summary In this study, a new air lift loop photoreactor was used for both continuous and non-continuous water photodetoxification. Also, the kinetics of phenol photodegradation were measured under flow conditions. Both the kinetics of phenol adsorption on TiO₂/SiO₂ and of the total photo-mineralization of phenol were measured in order to gain more knowledge on the photocatalytic oxidation of phenol on illuminated titania.Adsorption of phenol on TiO₂/SiO₂ proceeds even from diluted solutions. However, based on our data, it is impossible to state precisely the influence of the adsorption on the overall rate of phenol photodecomposition. The photoreaction yields stable intermediates which subsequently undergo total mineralization to CO₂ and H₂O. It is postulated that the intermediates consist mainly of polymeric compounds, difficult to determine by conventional analytical methods like GC, HPLC, or UV/Vis spectroscopy.

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Photolyse von Phenol in einem Durchflußreaktor: Adsorption und Kinetik

Zusammenfassung Ein neuartiger Photoreaktor wurde auf seine Verwendbarkeit zur kontinuierlichen und nichtkontinuierlichen Wasseraufbereitung getestet. Die Kinetik des photolytischen Abbaus von Phenol wurde unter Durchflußbedingungen untersucht. Zum besseren Verständnis der photokatalysierten Oxidation von Phenol auf belichtetem Titanoxid wurde außerdem die Kinetik sowohl der Adsorption von Phenol an TiO₂/SiO₂ als auch seiner Gesamtphotomineralisierung erforscht.Adsorption von Phenol an TiO₂/SiO₂ erfolgt bereits aus verdünnten Lösungen. Nach unseren Ergebnissen ist es allerdings unmöglich, den Einfluß der Adsorption auf die Photolyse genau zu bestimmen. Die Photoreaktion ergibt stabile Zwischenprodukte, die sich im weiteren Verlauf zu CO₂ und H₂O umsetzen. Es wird postuliert, daß es sich bei den Zwischenprodukten hauptsächlich um Polymere handelt, die mit konventionellen analytischen Techniken wie GC, HPLC oder UV/Vis-Spektroskopie schwer nachzuweisen sind.