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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].
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
Organic Catalysis by Clay-Supported Reagents
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
Clark et al. (1989) showed that benzyl alcohol reacted much more slowly (with benzene) than did benzyl chloride, while Laszlo (1998) reported that (at 20°C) toluene was not alkylated in the presence of clayzic and an equimolar mixture of benzyl alcohol and benzyl chloride. Aromatic hydrocarbon substrates can apparently act as their own solvents. Thus, the presence of benzene as a co-reactant significantly enhances the alkylation (by benzyl chloride) of toluene, mesitylene, or p-xylene (Cornélis et al. 1991a). Further, in a mixture of mesitylene and toluene, the relative reactivity toward benzyl chloride is inverted in that mesitylene is favored over toluene whereas the converse applies when the two substrates are separately benzylated (Cornélis et al. 1991b). Reactivity inversion in the benzylation of toluene by benzyl chloride and benzyl alcohol may partly be ascribed to preferential adsorption (to the solid catalyst) of benzyl alcohol (Yadav and Thorat 1996).
Occurrence of phthalates in facemasks used in India and its implications for human exposure
Published in International Journal of Environmental Health Research, 2022
Nandini Shende, Girivyankatesh Hippargi, Suyog Gurjar, Asirvatham Ramesh Kumar, Sadhana Rayalu
Stringent quality control measures were followed to minimize background contamination of PAEs. Only glass and stainless-steel containers and tools were used during sample preparation and analysis. To avoid adsorption of PAEs from laboratory air, mask samples were stored in aluminium foil packages and taken out only during extraction. Each sample was prepared in duplicate and analyzed in triplicates. The analytical results were within the relative standard deviation (RSD) of 10–20%. Procedural blanks and matrix spiked samples were analyzed for every 10 samples. Spike recoveries were in the range of 81–121%. A 7-point calibration in the range of 50–500 µg/L with a correlation coefficient of >0.99 was obtained for all analytes. Quantification was done using the internal standard (benzyl benzoate) method. All solvents had trace quantities of all PAEs, i.e. 0.5–1 µg/L, and blank samples had all five PAEs in the range of 1–3 µg/L. Previous studies also reported background contamination in blanks and solvents (Guo et al. 2012). The measured concentrations of samples were corrected for blank and spike recovery. LOD was in the range of 1.10–3.54 ng/g (Table 1). Concentrations reported as “not detected (ND)” were substituted by LOD/2 for statistical analysis.
Benzyl alcohol oxidation with Pd-Zn/TiO2: computational and experimental studies
Published in Science and Technology of Advanced Materials, 2019
Ewa Nowicka, Sultan Althahban, Tom D. Leah, Greg Shaw, David Morgan, Christopher J. Kiely, Alberto Roldan, Graham J. Hutchings
The oxidation of benzyl alcohol to benzaldehyde has been one of the most studied systems for selective oxidation of alcohols. This is due to its high reactivity, the limited number of products in the oxidation reaction and relatively well-known pathways for their formation. It has been generally accepted that benzaldehyde is obtained by the oxidation of benzyl alcohol in the presence of an oxidant and can undergo further oxidation to benzoic acid, which can in turn form benzyl benzoate (Equation 1; Ph stands for phenyl group) [4]. Toluene, considered as a by-product of this reaction, is believed to be formed in the disproportionation of benzyl alcohol (Equation 2) [5].
Sugarcane bagasse fiber reinforced composites: Recent advances and applications
Published in Cogent Engineering, 2020
Deepa G. Devadiga, K. Subrahmanya Bhat, GT Mahesha
Peroxide contains a specific functional group -ROOR, which can form a free radical RO that can react with the hydrogen group present in the matrix and cellulose fiber. Benzoyl group associated with benzyl chloride tends to reduce the hydrophilic nature of the treated fiber and tends to improve the interaction with the hydrophobic polymer matrix. Benzoylation of fibers shows better results when the fibers are pre-treated with alkali solution. This helps better fiber matrix linkage, increase in the strength of composites, reduction of water absorption, and improving its thermal stability (Bam et al., 2019).