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Noble Metal Nanoparticles in Organic Catalysis
Published in Varun Rawat, Anirban Das, Chandra Mohan Srivastava, Heterogeneous Catalysis in Organic Transformations, 2022
Laxmi Devi, Komal, Sunita Kanwar, Kamal Nayan Sharma, Anirban Das, Jyotirmoy Maity
Au NP (2–5 nm-sized) on ceria were used to oxidize alcohols like 2-hydroxybenzyl alcohol, 2-phenoxyethanol, vanillin alcohol, cinnamyl alcohol, 3-phenyl-1-propanol and 3,4-dimethyoxybenzyl alcohol (Figure 3.5) using molecular oxygen at atmospheric pressure without the use of a base or solvent [21–23]. Au–Pd NP dispersed on TiO2/graphene oxide composites were used for oxidation of benzyl alcohol and 4-methoxybenzyl alcohol (Figures 3.6 and 3.7). Au NP on different metal oxides (TiO2, ZnO, Fe2O3, MgO2 and Al2O3,) was used to obtain benzaldehyde (from benzyl alcohol) and acetophenone (from methylbenzyl alcohol) using tert-butylhydroperoxide as an oxidant under microwave irradiation for 1 h, with no by-products [24]. During the oxidation of benzyl alcohol, some by-products like benzoic acid and benzyl benzoate were also formed. Benzoic acid was formed due to the over oxidation of benzaldehyde and benzyl benzoate was formed because of additional esterification in the presence of benzoic acid and benzyl alcohol [14, 25].
Catalysis of Organic Reactions by Inorganic Solids
Published in John R. Kosak, Thomas A. Johnson, Catalysis of Organic Reactions, 2020
We shall focus here on the impressive substrate selectivity of clayzic. Such a selectivity is a prime goal in our design and construction of clay-based microreactors—we might term them “geozymes,” on a par with ribozymes, abzymes, chemzymes and other such enzyme mimics—that will emulate enzymatic efficiency. A spectacular example [23] is that of the competition between benzyl alcohol (BnOH) and benzyl chloride (BnCl) for alkylation of a substrate such as toluene. When taken alone, in the presence of clayzic as catalyst, the chloride is much more reactive. At room temperature, BnCl benzylates toluene, whereas BnOH is inactive. It takes temperatures of about 100°C for BnOH to match the reactivity of BnCl at room temperature. However, when the two reagents BnCl and BnOH are commixed, the alcohol inhibits the chloride to such an extent as to invert the reactivities. For instance, at 80°C, in the presence of an excess of the aromatic hydrocarbon substrate serving as its own solvent, the clay micro-reactor performs genuine batch processing of a BnCl-BnOH mixture. The reaction is sequential: the alcohol molecules first react; after they have all been converted into alkylated product, and only then, do the chloride molecules start to react and to be converted in turn.
Chemicals from Aromatic Hydrocarbons
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
The ratio of the chloride mixture mainly derives from the toluene/chlorine ratio and the contact time. Benzyl chloride is produced by passing dry chlorine into boiling toluene (110°C, 230°F) until reaching a density of 1.283. At this density, the concentration of benzyl chloride reaches the maximum. Light can initiate the reaction. Benzyl chloride can produce benzyl alcohol by hydrolysis, represented simply as: C6H5CH2Cl+H2O→C6H5CH2OH+HCl
Synthesis of a 2,4-DcCoPc/MIL-101(Fe) composite and catalytic oxidation of styrene to benzaldehyde
Published in Journal of Coordination Chemistry, 2021
Yanbing Yin, Zhaosong Xin, Hang Yang, Guopeng Xu, Yang Liu, Xiaolong LI
Benzaldehyde is the simplest aromatic aldehyde and is the most commonly used aromatic aldehyde in industry [1, 2]. It is widely used in synthetic medicine, plastic additives, flavors and fragrances, and agrochemicals [3, 4]. Synthesis methods for benzaldehyde mainly include toluene chlorination and then hydrolysis, direct oxidation of toluene and oxidation of benzyl alcohol [5–7]. However, these methods have disadvantages such as low catalytic activity and serious environmental pollution, especially the toluene chloride method, which makes benzaldehyde containing chloride and cannot be used in medicine and flavor industries [8, 9]. Therefore, it is essential to find an efficient and green synthesis [10]. Oxidation of styrene to benzaldehyde has become a hot topic [11]. Fu et al. prepared Cu/Co metal-organic mixed skeletons with different ratios and controlled the Cu/Co ratio, which showed high catalytic activity for styrene but low selectivity for benzaldehyde [12]. Chaudhary et al. synthesized Cu(II) and Mn(II) metals embedded in the mesoporous molecular sieve SBA-15 by coprecipitation, and the catalyst showed high catalytic activity to styrene [13]. However, although these catalytic reactions improve the conversion rate of styrene, they are not selective to benzaldehyde and produce heavy metal ions that are harmful to the environment [14, 15]. Therefore, the preparation of a catalyst with high catalytic activity, good selectivity for styrene to benzaldehyde and environmental friendliness is important [16, 17].
Green synthesis of a vanadium(V) Schiff base complex by grinding method: study on its catalytic and anti-bacterial activity
Published in Journal of Coordination Chemistry, 2021
Jeena Jyoti Boruah, Zankhana S. Bhatt, Chirag R. Nathani, Vaishali J. Bambhaniya, Ankur Kanti Guha, Siva Prased Das
Na[VO2L] efficiently, catalytically and selectively oxidized benzyl alcohol into benzaldehyde or benzoic acid with hydrogen peroxide as oxidant. The oxidation reactions were solventless and achieved product selectivity by simply controlling the reaction conditions. The use of 1.1 equivalent of hydrogen peroxide with respect to benzyl alcohol produced benzaldehyde as sole product with high purity (Table 5). On the other hand, use of 3.0 equivalent of hydrogen peroxide with respect to benzyl alcohol produced benzoic acid as sole product. The reactions under microwave irradiation are much faster than with classical heating methods. The selective oxidation of benzyl alcohol to benzaldehyde was completed in 10 min of microwave irradiation whereas the same reaction under heating condition needed 2.5 h to complete. No oxidation took place in the absence of Na[VO2L] under identical reaction conditions. This indicated that Na[VO2L] played a vital role in the oxidation process. We have extended the catalytic alcohol oxidation activity of Na[VO2L] towards oxidation of 4-nitrobenzyl and 4-chlorobenzyl alcohols and the results are summarized in Table 5. Na[VO2L] efficiently and selectively oxidized the substrates under classical heating and microwave methods.
Synthesis, catalysis, antimicrobial activity, and DNA interactions of new Cu(II)-Schiff base complexes
Published in Inorganic and Nano-Metal Chemistry, 2020
Mohamed Shaker S. Adam, Laila H. Abdel-Rahman, Ahmed M. Abu-Dief, Nahla A. Hashem
Benzyl alcohol (0.13 mL, 1.0 mmol) was injected to a solution of Cu(II)-complexes (0.02 mmol) contacted to air in acetonitrile, as organic solvent (10 mL), at 50, 60, 80, or 90 °C in an oil bath with continuous stirring. The reaction was fed with an aqueous H2O2 (0.1 mL, 3 mmol, 30%) at the given temperature. The reaction was monitored by GC analyses, charged with computerized standard calibration curve. By comparing the retention times of the resulted oxidation product with the authentic samples, the products could be identified. Control reactions were carried out by withdrawing samples (ca. 0.2 mL) of the reaction mixture at the typical time. The taken samples were treated with MnO2 (20 mg) to quench the excess H2O2 and with anhydrous sodium sulfate (20 mg) to absorb water, under the typical conditions in the catalytic runs. The resulting slurry was filtered on celite, and the filtrate was injected in the Gas Chromatography. This allowed independent measurements for each sample. The conversion of benzyl alcohol to benzaldehyde and/or benzoic acid was determined by the computerized standard calibration curves.[24]