Nitration Of Chlorobenzene Research Articles

Nitration of chlorobenzene by ultrasonic-assisted synthesized sulfated ZrO2 catalyst with NO2

Nitration of chlorobenzene by ultrasonic-assisted synthesized sulfated ZrO2 catalyst with NO2

Determination of the kinetics of chlorobenzene nitration using a homogeneously continuous microflow

AbstractThe nitration of chlorobenzene with concentrated mixed acids is a fast and highly exothermic process, which suffers from considerable mass transfer resistance and poor heat transfer rates. The reaction kinetics has not been thoroughly reported before. In this work, a continuous‐flow microreactor system and a homogeneous reaction condition were proposed to obtain accurate chlorobenzene nitration kinetics parameters at high mixed acid concentrations. A general model for predicting the observed reaction rate constants was established. With a new method for estimating the equilibria associated with HNO3 in aqueous sulfuric acid, the rate constants based on nitronium ion and activation energies were obtained. Compared with batch reactors, the continuous‐flow microreactor system allows for a sufficient heat transfer efficiency and accurate residence time control, making it possible to study the reaction performance more quickly and sensitively. This work may provide a reliable reference for the kinetic study of similar processes.

Regioselective mononitration of chlorobenzene using caprolactam-based Brønsted acidic ionic liquids

Three kinds of Brønsted acidic ionic liquids caprolactam benzenesulfonate ([CP]BSA), caprolactam hydrosulfate ([CP]HSO4) and caprolactam p-toluenesulfonate ([CP]pTSA) were synthesized. The structures of the ILs were confirmed by 1HNMR and FT-IR. Regioselective mononitration of chlorobenzene has been investigated in HNO3–Ac2Osystem with three ionic liquids. The sequence of the nitrification activity is [CP]HSO4>[CP]pTSA>[CP]BSA. With the caprolactam hydrosulfate as the catalyst the influences of reaction time, reaction temperature and the amount of the catalyst were studied in the nitration of chlorobenzene. The results showed that the optimum reaction conditions were as follows: when the mole ratio of chlorobenzene to ionic liquid was 10:1.5, the reaction temperature was 60°C and the reaction time was 2.5h, the yield of mononitro-chlorobenzene could reach 71.22%. And the mass ratio of para/ortho isomer was 7.74, which was much more than 2.0 of para/ortho isomer mass ratio obtained by nitric-sulfuric mixed acids as catalyst. Besides, the ionic liquid could be used repeatedly.

Selective Nitration of Chlorobenzene by NO2 in the Alkali Zeolite NaZSM-5

Chlorobenzene was reacted with NO2, in the initially acid-free zeolite NaZSM-5, to yield para-chloronitrobenzene exclusively. The precursors were loaded sequentially into self-supporting pellets of the zeolite, contained within a stainless steel cell, from the gas phase. The reaction proceeds spontaneously at room temperature. It is, however, very temperature dependent and effectively ceases at zero degrees Celsius. The reaction was monitored in situ using FT-IR. The active nitrating agent is formed from the partial electron donation by the NO2 to the Na+ cations present in the zeolite lattice. Under the reaction conditions, chlorobenzene is not readily mobile through the pore system; thus, only the molecules adsorbed near a cation site react to form para-chloronitrobenzene.

Mass transfer of chlorobenzene in concentrated sulfuric acid

Mass transfer of chlorobenzene in sulfuric acid is very important in the nitration of chlorobenzene by mixed acid. This article presents the determination of mass transfer coefficient at high-concentrations of sulfuric acid at 298 K and 313 K at 2 π rad/s and 4 π rad/s impeller speeds. The experiments were carried out under flat-interface conditions in an unbaffled glass reactor of 10 cm diameter and 1 dm 3 capacity. A glass stirrer with two paddle-type impellers was employed for stirring. The upper paddle stirred the organic phase and the lower paddle stirred the aqueous phase. High mass transfer coefficients were obtained at high-concentrations of sulfuric acid. Dynamic light scattering of the aqueous phase revealed that a dispersion of chlorobenzene spontaneously formed in sulfuric acid, which is believed to be the main factor behind the high mass transfer coefficient. NMR analysis of the aqueous phase showed that no chemical reaction occurred at 298 K and 313 K, but some amount of 4-chlorobenzenesulfonic acid formed at 323 K. The high mass transfer coefficient is expected to result in high yield of chloronitrobenzenes at moderate temperatures and low stirring speeds.

Nitration of chlorobenzene with nitric acid in a continuous installation

The procedures of production of mononitrochlorobenzene by nitration with 75-97% nitric acid with the yield of the target product of 97.5% were developed. A procedure of precipitation of crystalline p-nitrochlorobenzene from the reaction mixture without additional purification was proposed.

Kinetics and Mechanism of the Nitration of Chlorobenzene with Nitric Acid

The rate of homogeneous nitration of chlorobenzene with 70-90% nitric acid is proportional to the chlorobenzene concentration and activity of nitric acid. The existence of linear correlations between the rate constants k 2ap and the acidity function -H and between logk * 2ap values (calculated using NO2 + concentration) and the acidity function -(H R + logaH 2O) indicates that the nitrating species is nitronium ion generated by reaction of H3O+ with nitric acid monohydrate. Increase in the energy of activation with rise in water concentration is explained by increase of ΔH for equilibrium formation of nitronium ion.

Effect of perchlorate ion on the textural and catalytic activity of zirconia

Synthesis and physico-chemical characterization of hydrous zirconia gel were carried out. The perchlorate sorption properties of hydrous zirconia were found to be appreciable and a loading of about 9 wt% was possible in an equilibrium solution of 0.1 M HClO 4. Formation of perchlorated zirconia has been investigated using XRD, TG/DTA and FTIR. Nitrogen adsorption desorption isotherms at liquid nitrogen temperature were used to explore the surface area and porosity of the samples. The nitration of chlorobenzene was used as the test reaction. It was observed that finely divided zirconia with mesoporous texture can be prepared using preshaped precipitating medium. The XRD patterns revealed that perchlorate ion stabilizes the tetragonal phase of zirconia. TG/DTA and FTIR studies supported the presence of perchlorate moiety in the sample. The surface acidity measurement using different organic bases irreversibly adsorbed on zirconia surface showed that perchlorated samples are highly acidic up to a temperature of 250°C, which drastically decreased on further heating. The material modified with perchlorate ion was found to be an efficient and selective catalyst for solvent-free mononitration of chlorobenzene.

Selectivity engineering in the nitration of chlorobenzene using eclectically engineered sulfated zirconia and carbon molecular sieve catalysts

Selective synthesis of the para‐nitro derivative from chlorobenzene by using nitric acid over an eclectically engineered sulfated zirconia carbon molecular sieve catalyst is reported. The p : o ratio in chlorobenzene nitration was found to be very high with eclectically engineered sulfated zirconia and carbon molecular sieve catalyst.

Transition metal pillared clay:: 3. A para selective catalyst for nitration of chlorobenzene

Nitration of chlorobenzene has been studied at different temperatures using transition metal (Fe(III), Cr(III), Mn(III)) pillared clays as the catalysts. All the samples showed high para selectivity (up to 94%). The acid activated pillared clays calcined at 300°C showed higher activity than the nonactivated pillared clays which followed the order: iron oxide pillared acid-activated clay>chromium oxide pillared acid-activated clay>manganese oxide pillared acid-activated clay whereas the selectivity order is chromium oxide pillared acid-activated clay>manganese oxide pillared acid-activated clay>iron oxide pillared acid-activated clay.

Effect of Process Conditions on Formation of Isomers in Nitration of Chlorobenzene

Effect of Process Conditions on Formation of Isomers in Nitration of Chlorobenzene

O-, m- and p- Substitution Reaction. V-VII. VII. Nitration of Chlorobenzene by Nitric Acid and Acetic Acid Mixture.

o-, m- and p- Substitution Reaction. V-VII. VII. Nitration of Chlorobenzene by Nitric Acid and Acetic Acid Mixture.

O-, m- and p- Substitution Reaction. V-VII. V. Nitration of Chlorobenzene by Nitric Acid and Sulfuric Acid Mixture. (2)

o-, m- and p- Substitution Reaction. V-VII. V. Nitration of Chlorobenzene by Nitric Acid and Sulfuric Acid Mixture. (2)

On the Nitration of Chlorobenzene. I

On the Nitration of Chlorobenzene. I