Kinetic study on oxidative bromination of 2,6-dichlorotoluene to 2,6-dichlorobenzyl bromide in a microchannel reactor under light irradiation

doi:10.21203/rs.3.rs-2107246/v1

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Kinetic study on oxidative bromination of 2,6-dichlorotoluene to 2,6-dichlorobenzyl bromide in a microchannel reactor under light irradiation

https://doi.org/10.21203/rs.3.rs-2107246/v1

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2,6-dichlorobenzyl bromide (DCBB) is an important drug intermediate for the preparation of antibacterial and antitumor agents. DCBB was prepared by the photocatalytic benzylic bromination of 2,6-dichlorotoluene (DCT) with hydrogen peroxide and hydrobromic acid as bromine source in a microchannel reactor, which belongs to a green and safe, economical and environmentally friendly process. Herein, the work focused on the investigation of kinetics of oxidative bromination of DCT to DCBB, and a kinetic model for this process was proposed. A series of kinetic data were obtained under kinetically controlled conditions by eliminating the mass transfer effects of liquid-liquid phases, and the experimental data were fitted nonlinearly using Matlab software. The results showed that the calculated values based on the kinetic model were in good agreement with the empirical values, and the preexponential factor and activation energy were 635.3 and 24.0 KJ/mol, respectively, and high concentration of DCT inhibit the response.

6-dichlorotoluene

6-dichlorobenzyl bromide

microchannel reactor

kinetics

photocatalytic benzylic bromination

2,6-Dichlorobenzyl bromide (DCBB) is an important intermediate in the synthesis of many drugs [1–3]. DCBB could be synthesized from 2,6-dichlorotoluene (DCT) by means of radical benzylic bromination of toluene derivatives with molecular bromine under light irradiation or in the presence of free radical initiator, a traditional protocol for obtaining benzyl bromides[4]. However, bromination with molecular bromine suffers from the disadvantages of difficult transportation and storage of molecular bromine due to its toxicity and high vapor pressure, and low atom efficiency due to HBr as a by-product in the reaction [5].

Various regents and oxidative bromination systems have been developed to replace molecular bromine in benzylic bromination, including H₂O₂/HBr/NBS [6], BBr₃ [7], NBS/SiCl₄ [8], H₂O₂/NaBr/H⁺ [9], H₂O₂/HBr [10, 11], NaBrO₃/NaBr/H⁺[12]. KBr/Oxone [13], NaNO₂/KBr/HCl [14], etc. Among these protocols, the photocatalytic oxidative bromination with HBr/H₂O₂ is the most advantageous due to low cost of both hydrobromic acid and H₂O₂, 100% atom efficiency of bromine source, as well as water as the unique byproduct avoiding the environmental problems associated with the other protocols[11]. Traditionally, the photocatalytic oxidative benzylic bromination with HBr/H₂O₂ was conducted in a batch reactor [6, 15], which suffers from the disadvantages of risk of explosion, ununiformity and small area of light irradiation, mixing difficulty of aqueous and organic phases, as well as decomposition of hydrogen peroxide due to long retention time especially in scale-up application.

In recent years, the advancement of science and technology has led to the rapid development of microchannel reactor technology [16–20], which has made microchannel reactors widely used in the field of photocatalytic chemistry [21–29], including photocatalytic benzyl bromination reactions [30–33]. Reaction in a microchannel reactor can overcome the problems associated with that in a batch reactor. Performing a photocatalytic reaction in a microchannel reactor get benefits of not only the enhanced heat and mass transfer, but also the intense and uniform irradiation of the reaction mixture. Furthermore, the reaction can be conducted under higher substrate concentrations due to the short path length of the irradiation light in a capillary microreactor, thus led to significant increase of reaction throughput. Meanwhile, the light exposure can be precisely controlled by the pump flow rate, which minimizes over irradiation of the reaction mixture, preventing the formation of undesired by-products [30]. For instance, the scale-up synthesis of DCBB was performed in a microreactor with NaBrO₃/HBr as bromine generator with residence time of 18s. In a typical case, 1.17 kg (97% yield) of DCBB was isolated in a yield of 97% in less than 4 h processing.

Very recently, we developed a green and safe process for the synthesis of (DCBB) by conducting photocatalytic benzylic bromination of DCT with H₂O₂ as an oxidant and HBr as a bromine source in a microchannel reactor. The conversion of DCT reached up to 98.1% with a DCBB yield of 91.4% under the optimal reaction conditions, which means that this process is potential in scale-up application. The gratifying results inspired us to investigate the kinetics of this process, which could reveal the interactions between reactants and provide basic data for the design, optimization and industrial scale-up of process-specific reactors.

2.1. Kinetic model

At present, no investigations on the kinetics of benzylic bromination of DCT to DCBB under light irradiation are reported in literature. Therefore, it is necessary to reveal the kinetics of this reaction in a microchannel, which is a fundament for scale up production of DCBB in this process. The investigation was conducted in a microreactor system as shown in Fig. 5. In the experiments, aqueous HBr and H2O2 mixed through a tree-way valve leading to in situ generation of Br2 before entering the microchannel reactor in the experiments. Therefore, Br2 can be regarded as the actual bromination agent in the reaction. As is known, the photocatalytic bromination of DCT is a free radical chain reaction [34], it is difficult to establish a kinetic model based on the elementary reactions. Here, an intrinsic kinetics was proposed based on the initial results: Almost no benzylic dibromo and tribromo products, α,α-dibromo-2,6-dichlorotoluene (DBDCT) and α,α,α-tribromo-2,6-dichlorotoluene (TBDCT) were found under the specific experimental conditions, though three benzylic bromination products, DCBB, DBDCT and TBDCT could be generated in principle; The unexpected product 2,6-dichlorobenzoic acid (DCBA) was formed almost in constant selectivity under the specific reactions. Figure 2 shows the intrinsic kinetic scheme for the benzylic bromination of DCT to DCBB.

Since the benzylic bromination of DCT in a microchannel reactor is significantly complicated, many parameters must be empirically adjusted. Therefore, the well-known power law model is used to fit the experimental data. Because the benzylic bromination reaction is not reversible, especially in the H₂O₂-HBr system [35], the reaction rate equation can be expressed as

$${\text{r}}_{\text{A}}\text{=-}\frac{\text{d}{\text{C}}_{\text{A}}}{\text{dt}}\text{=k}{\text{C}}_{\text{A}}^{{\text{α}}_{\text{1}}}{\text{C}}_{\text{B}}^{{\text{α}}_{\text{2}}}$$

According to Arrhenius equation

$$\text{k=}{\text{k}}_{\text{0}}\text{ }\text{exp}\text{ }\text{(-}\frac{{E}_{a}}{\text{RT}}\text{)}$$

Then the kinetic model is expressed as

$${\text{r}}_{\text{A}}\text{=-}\frac{\text{d}{\text{C}}_{\text{A}}}{\text{dt}}\text{=}{\text{k}}_{\text{0}}\text{ }\text{exp(-}\frac{{E}_{a}}{\text{RT}}\text{)}{\text{C}}_{\text{A}}^{{\text{α}}_{\text{1}}}{\text{C}}_{\text{B}}^{{\text{α}}_{\text{2}}}$$

where C_i (i = A, B) are the concentrations of DCT and Br₂, mol⋅L^-1; E_a is the activation energy, J⋅mol^-1; k is the reaction rate constant; k₀ is the preexponential factor; r_A is the reaction rate of DCT, mol⋅L^-1⋅s^-1; R is the molar gas constant, 8.314 J⋅mol^-1⋅K^-1; T is the reaction temperature, K; t is the reaction time, s; α_i (i = 1,2) are the reaction orders of DCT and Br₂.

2.2. Eliminate the effect of mass transfer

Since the aqueous solution of HBr and the aqueous solution of H2O2 have been pre-mixed and generated Br2 in situ before entering the microchannel reactor, when the aqueous phase is mixed with the organic phase, the solubility of Br2 in the organic phase solvent 1,2-dichloroethane is much greater than that in the aqueous phase, so Br2 will quickly enter the organic phase and participate in the reaction to produce HBr, while the solubility of HBr in the aqueous phase is much greater than that in the organic phase, HBr will be returned from the organic phase back into the aqueous phase and continue the reaction with H2O2. To get the intrinsic rate data of a reaction in a microchannel reactor, it is necessary to conduct kinetic studies in the regime where mass transfer is absent. Therefore, we made selection of the range of residence time in which the external diffusion of reactants was absent. The experiments were carried out under DCT:HBr:H2O2 molar ratios of 1.0:1.1:1.1, reactant concentrations of DCT 21.0 wt.%, HBr 16.33 wt.%, H2O2 7.71 wt.%, 0.8 MPa pressure, and 87 W blue light irradiation at 70 oC with variation of residence time. Under the same residence time, the reaction was carried out in different volumes of the same microchannel reactor (V1 = 23.7 mL, V2 = 17.6 mL). As shown in Fig. 3, the conversion of DCT was hardly changed with the variation of the volume of the same microchannel reactor when the residence time is less than 350 s. That was to say, the effect of mass transfer on the reaction could be ignored if the residence time is less than 350 s.

Reaction Conditions: 87 W blue light; DCT:HBr:H₂O₂ (molar ratio) = 1:1.1:1.1; solution A: 21.0 wt.% solution of DCT (0.141 mol) in 1, 2-dichloroethane (73.0 mL); solution B: 16.33 wt.% of HBr aqueous solution; solution C: 7.71 wt.% of H₂O₂ aqueous solution; reaction pressure = 0.8 MPa; reaction temperature = 70 ^oC.

2.3. Kinetic parameter estimation

Kinetic parameter estimation is a necessary step to describe a kinetic model for a given chemical reaction[36], therefore, the variations of DCT and Br₂ concentrations (C_A and C_B) with time were investigated in the temperature range of 20 ~ 50 ^oC. The results are listed in Table 1.

Table 1

Data of the concentration of C_A and C_B over time at 20 ^oC to 50 ^oC
run	t/s	T/ ^oC	C_A/(mol⋅L^− 1)	C_B/(mol⋅L^− 1)
1	10.1	20	1.5138	0.8379
2	14.7	20	1.5007	0.8312
3	20.3	20	1.4823	0.8228
4	24.3	20	1.4635	0.8125
5	30.4	20	1.4432	0.8021
6	36.0	20	1.4228	0.7906
7	10.1	30	1.4938	0.8275
8	14.7	30	1.4735	0.8172
9	20.3	30	1.4513	0.8066
10	24.3	30	1.4291	0.7952
11	30.4	30	1.4028	0.7804
12	36.0	30	1.3714	0.7627
13	10.1	40	1.4748	0.8178
14	14.7	40	1.4407	0.8009
15	20.3	40	1.4084	0.7842
16	24.3	40	1.3787	0.7654
17	30.4	40	1.3398	0.7498
18	36.0	40	1.2850	0.7225
19	10.1	50	1.4192	0.7891
20	14.7	50	1.3761	0.7664
21	20.3	50	1.3154	0.7384
22	24.3	50	1.2821	0.7204
23	30.4	50	1.2192	0.6873
24	36.0	50	1.1529	0.6522
Reaction condition: 87 W blue light; DCT:HBr:H2O2 (molar ratio) = 1.0:1.1:1.1, solution A: 21.0 wt.% solution of DCT (0.141 mol) in 1, 2-dichloroethane (73.0 mL); solution B: HBr aqueous solution, 16.33 wt.%; solution C: H2O2 aqueous solution, 7.71 wt.%; reaction pressure = 0.8 MPa.

The data in Table 1 were firstly subjected to multiple linear regression using Matlab software to obtain the initial values of each parameter. The initial values were then substituted into the non-linear regression to obtain the calculated values of the kinetic model parameters. The parameter data were brought into Eq. (4) to obtain the kinetic model:

$${\text{r}}_{\text{A}}\text{=-}\frac{\text{d}{\text{C}}_{\text{A}}}{\text{dt}}\text{=}\text{635.3}\text{exp (-}\frac{\text{2.40}\text{×}{\text{10}}^{\text{4}}}{\text{RT}}\text{)}{\text{C}}_{\text{A}}^{\text{-4.19}}{\text{C}}_{\text{B}}^{\text{3.22}}$$

In the kinetic model the activation energy is 2.40×10⁴ J⋅mol^− 1, indicating the reaction can proceed under mild conditions. The negative reaction order of DCT (-4.19) indicates that high DCT concentration is unfavorable for benzylic bromination of DCT, which could be ascribed to the difficulty in mixing of aqueous and organic phases at high concentration of DCT.

The F statistical test [37, 38] was used to evaluate the adaptability of the kinetic model according equations, and the test results are given in Table 2.

Statistical test:

$$\text{F=}\frac{{\text{S}}_{\text{ESS}}/\text{P}}{{\text{S}}_{\text{RSS}}/\left(\text{N-P-1}\right)}\text{>10}{\text{×}\text{F}}_{\text{α}}$$

Multiple correlation index:

$${\text{R}}^{\text{2}}\text{=1-}\frac{{\text{S}}_{\text{RSS}}}{{\text{S}}_{\text{TSS}}}\text{>0.9}$$

Among them, the total sum of squares:

$${\text{S}}_{\text{TSS}}\text{=}\sum _{\text{i=1}}^{\text{N}}{\left({\text{C}}_{\text{i}}\text{-}\stackrel{\text{-}}{\text{C}}\right)}^{\text{2}}$$

Explained sum of squares:

$${\text{S}}_{\text{ESS}}\text{=}\sum _{\text{i=1}}^{\text{N}}{\left(\widehat{\text{C}}\text{-}\stackrel{\text{-}}{\text{C}}\right)}^{\text{2}}$$

Residual sum of squares:

$${\text{S}}_{\text{RSS}}\text{=}\sum _{\text{i=1}}^{\text{N}}{\left({\text{C}}_{\text{i}}\text{-}\widehat{\text{C}}\right)}^{\text{2}}$$

where, N is the number of experimental data sets; P is the number of parameters to be estimated; C_i is the experimental measurement value;‾C is the experimental average;$\text{ }\widehat{\text{C}}$ is the calculated value; α is the significance level, generally takes 0.05.

Table 2

F-test of intrinsic kinetic models
Equation	(4)
P	4
N – P – 1	19
R²	0.9794
F	224.35
10×F_α=0.05	28.95
10×F_α=0.005	52.70

As can be seen from Table 2, the multiple correlation index of the proposed model is greater than 0.9 and the F-statistic is greater than 10 times the critical F-statistic with a confidence domain of 95% and 99.5%. Figure 4 shows the distribution of the residuals of the reaction rate, which are more evenly distributed around the zero line and the sides, these suggest that the model is significantly valid.

The kinetics of the oxidative bromination of DCT was studied in the temperature range of 20°C to 50°C, and the intrinsic kinetic model of the reaction system was established, with the preexponential factor and activation energy of 635.3 and 24.0 KJ/mol, respectively. The results of statistical tests showed that the data calculated by the intrinsic kinetic model were in good agreement with the experimentally obtained data.

4.1. Regents and instruments

All reagents were analytical grade and used as received without further purification. 2,6-Dichlorotoluene (DCT) and hydrobromic acid (HBr, 40.0 wt.%) were provided by Shanghai Taitan Chemical Reagent Cooperation. 1,2-dichloroethane and aqueous hydrogen peroxide (H₂O₂, 30.0 wt.%) was provided by Fuchen (Tianjin) Chemical Reagent Co. Deionized water is prepared by ourselves in our laboratory. Hydrobromic acid (HBr, 40.0 wt. %) and hydrogen peroxide (H₂O₂, 30.0 wt. %) were used after calibration.

The oxidative benzylic bromination of DCT under light irradiation was carried out in a Kiloflow-type continuous flow microchannel reactor from Chemtrix B.V. (Echt, The Netherlands). The light source was at a wavelength of 435–445 nm. The reaction solution was illuminated by placing three lamp plates with a power of 5 W and two lamp strips with a power of 36 W at a distance of 5 mm from the glass reaction plate of the microchannel reactor. The reaction solution was analyzed on a Shimadzu high-performance liquid chromatograph (HPLC) equipped with a Shim-pack VP-ODS C₁₈ column.

4.2. Oxidative bromination of DCT

30 wt.% H₂O₂ and 40 wt.% HBr were each added to an appropriate amount of deionized water to form 7.11 wt.% H₂O₂ and 16.33 wt.% HBr respectively; 160.8 ml of 1,2-dichloroethane was added to 50 g (0.311 mol) of DCT to form 21.0 wt.% DCT.

In a typical experiment, H₂O₂ (16.33 wt.%) and HBr (7.11 wt.%) were first mixed through a three-way valve and then mixed with the DCT solution (21.0 wt.%) in a second three-way valve. The mixture entered the microchannel reactor where the reaction was completed at a set temperature and pressure. After exiting the reactor, the reaction solution passed through a backpressure valve and was quenched at low temperature (0°C) in a cold trap. The reactor pressure was monitored by a pressure gauge at the inlet and controlled by a back pressure valve at the outlet throughout the process.

The standard curves of DCT and DCBB were established by high performance liquid chromatography (HPLC) for the quantitative analysis of DCT and DCBB in the reaction solution. The determination of concentration of Br₂ in the study of reaction kinetics was as follows: The initial concentration of DCT was selected to be 1.5475 mol/L. The DCT to HBr molar ratio was 1:1.1, therefore, the initial concentration of Br₂ was 0.8557 mol/L assuming the immediate transformation of HBr to Br₂ in contact with H₂O₂. The Br₂ concentration C_B was then obtained from Eq. (10) based on the fact that DCBB was the only bromide product detected in the reaction mixture.

$${\text{C}}_{\text{B}}\text{=0.8557-0.5}\left[\text{DCBB}\right]\left(\text{mol/L}\right)$$

Where, the concentration of DCBB was determined by HPLC.

The conversion rate of DCT and the selectivities towards DCBB were calculated using the following formulas:

$$\text{DCT conversion}\text{ }\text{=}\text{ }\frac{{\text{n}}_{\text{DCT}\text{, }\text{converted}}}{{\text{n}}_{\text{DCT}\text{, }\text{initial}}}\text{×}\text{ }\text{100}\text{\%}$$

$$\text{DCBB}\text{ }\text{selectivity}\text{ }\text{=}\text{ }\frac{{\text{n}}_{\text{DCBB}\text{ }}}{{\text{n}}_{\text{DCT}\text{, }\text{converted}\text{ }}}\text{×}\text{ }\text{100\%}$$

n_{DCT, initial} and n_{DCT, converted} are the initial and converted amounts of DCT in moles, respectively. n_DCBB is the amounts of DCBB formed in moles, respectively.

Acknowledgments

The authors very much appreciate the financial support from the Foundation of Central Government Guides Local Science and Technology Development (Grant No.206Z4001G, 216Z1401G).

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Authors' contributions

Minghui Xiao, Lin Liu performed the experiment; Minghui Xiao, Lin Liu, Lei Wang contributed significantly to analysis and manuscript preparation; Minghui Xiao, Lin Liu, Hongyu Zhang, Yaping Han, Yuecheng Zhang performed the data analyses and wrote the manuscript; Hongyu Zhang, Yaping Han, Yuecheng Zhang, Jiquan Zhao helped perform the analysis with constructive discussions.

Funding

School of Chemical Engineering, Hebei University of Technology, Tianjin 300401, P.R. China

Tianjin Meide Biotechnology Co. Ltd, Tianjin 300408, P.R. China

Hebei Provincial Key Lab of Green Chemical Technology and High Efficient Energy Saving, Hebei University of Technology, Tianjin 300401, P.R. China

Availability of data and materials Not applicable

H. Han, C. He, X. Chen, Y. Luo, M. Yang, Z. Wen, J. Hu, F. Lin, M. Han, T. Yin, R. Yang, H. Lin, J. Qi, and Y. Yang, Bioorganic & Medicinal Chemistry Letters 57, 128503 (2022).
S. Indumathi, R. R. Kumar, and S. Perumal, Tetrahedron 63, 1411 (2007).
P Apiltd, B Brak, (27 August 2015).
I. Saikia, A. J. Borah, and P. Phukan, Chem Rev 116, 6837 (2016).
J. H. Clark, Green Chem. 1, 1 (1999).
A. Podgoršek, S. Stavber, M. Zupan, and J. Iskra, Tetrahedron 65, 4429 (2009).
H. Chen, L. Shen, and Y. Lin, Synthetic Communications 40, 998 (2010).
T. Salama and Z. Novák, Tetrahedron Letters 52, 4026 (2011).
R. Mestres and J. Palenzuela, Green Chem 4, 314 (2002).
A. Podgoršek, S. Stavber, M. Zupan, and J. Iskra, Tetrahedron Letters 47, 7245 (2006).
A. Amati, G. Dosualdo, L. Zhao, A. Bravo, F. Fontana, F. Minisci, and H.-R. Bjørsvik, Org Process Res Dev 2, 261 (1998).
S. Adimurthy, S. Ghosh, P. Patoliya, G. Ramachandraiah, M. Agrawal, M. Gandhi, S. Upadhyay, P. Ghosh, and B. Ranu, Green Chem 10, 232 (2008).
M. Zhao, M. Li, and W. Lu, Synthesis 50, 4933 (2018).
M. Zhao and W. Lu, Org Lett 20, 5264 (2018).
J. Ju, Y. Li, J. Gao, J. Jia, L. Han, W.Sheng, and Y. Jia, Chinese Chemical Letters 22, 382 (2011).
W Ehrfeid, V Hessel, H Löwe, Microreactors: New Technology for Modern Chemistry. Wiley-VCH, Weinheim, Germany (2000).
P. Suryawanshi, S. Gumfekar, B. Bhanvase, S. Sonawane, and M. Pimplapure, Chemical Engineering Science 189, 431 (2018).
A. Bojang and H. Wu, Processes 8, 891 (2020).
H. Zhao, S. Liu, M. Shang, and Y. Su, Chemical Engineering Science 246, 116907 (2021).
M. Plutschack, B. Pieber, K. Gilmore, and P. Seeberger, Chem Rev 117, 11796 (2017).
Z. Gao, C. Pan, C. Choi, and C. Chang, Symmetry 13, 1325 (2021).
Z. Garlets, J. Nguyen, and C. Stephenson, Isr J Chem 54, 351 (2014).
R. Andrews, J. Becker, and M. Gagné, Angew Chem Int Ed 51,4140 (2012).
Y. Su, K. Kuijpers, N. König, M. Shang, V. Hessel, and T. Noël, Chem Eur J 22, 12295 (2016).
X. Shi, S. Liu, C. Duanmu, M. Shang, M. Qiu, C. Shen, Y. Yang, and Y. Su, Chemical Engineering Journal 420, 129976 (2021).
H. Ehrich, D. Linke, K. Morgenschweis, M. Baerns, K. Jahnisch, Chimia 56, 647, (2022).
H. Matsubara, Y. Hino, M. Tokizane, and I. Ryu, Chemical Engineering Journal 167, 567 (2011).
P. Löb, H. Löwe, and V. Hessel, Journal of Fluorine Chemistry 125, 1677 (2004).
W. Yu, D. Yu, M. Zheng, S. Shan, Y. Li, and J. Gao, Journal of Chemical Research 36, 258 (2012).
D. Cantillo, O. de Frutos, J. A. Rincon, C. Mateos, and C. O. Kappe, J. Org. Chem. 79, 223 (2014).
Y. J. Kim, M. J. Jeong, J. E. Kim, I. In, and C. P. Park, Aust. J. Chem. 68, 1653 (2015).
A. Steiner, J. Williams, O. Frutos, J. Rincón, C. Mateos, and C. Kappe, Green Chem. 22, 448 (2020).
A. Podgoršek, S. Stavber, M. Zupan, and J. Iskra, Green Chem. 9, 1212 (2007).
M. Kharasch, W. Hered, F. Mayo, J Org Chem 6, 818 (1941).
A. Amati, G. Dosualdo, L. Zhao, A. Bravo, F. Fontana, F. Minisci, and H. Bjørsvik, Org Process Res Dev 2, 261 (1998).
J. Leppävuori, M. Domach, L. Biegler, Ind Eng Chem Res 50, 12080 (2011).
Guo HX (2003) Applied Chemical Kinetics. Chemical Industry Press. Beijing, China (n.d.).
Wang RX (1999) Mathematical Statistics. Xi’AN Jiaotong University Press. Xi’an, China (n.d.).

No competing interests reported.

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Kinetic study on oxidative bromination of 2,6-dichlorotoluene to 2,6-dichlorobenzyl bromide in a microchannel reactor under light irradiation

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Abstract

Figures

1. Introduction

2. Result And Discussion

2.1. Kinetic model

2.2. Eliminate the effect of mass transfer

2.3. Kinetic parameter estimation

3. Conclusion

4. Experimental Section

4.1. Regents and instruments

4.2. Oxidative bromination of DCT

Declarations

References

Additional Declarations

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