scholarly journals Solid Acid Catalysts for the Hock Cleavage of Hydroperoxides

Catalysts ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 91
Author(s):  
Jan Drönner ◽  
Peter Hausoul ◽  
Regina Palkovits ◽  
Matthias Eisenacher

The oxidation of cumene and following cleavage of cumene hydroperoxide (CHP) with sulfuric acid (Hock rearrangement) is still, by far, the dominant synthetic route to produce phenol. In 2020, the global phenol market reached a value of 23.3 billion US$ with a projected compound annual growth rate of 3.4% for 2020–2025. From ecological and economical viewpoints, the key step of this process is the cleavage of CHP. One sought-after way to likewise reduce energy consumption and waste production of the process is to substitute sulfuric acid with heterogeneous catalysts. Different types of zeolites, silicon-based clays, heteropoly acids, and ion exchange resins have been investigated and tested in various studies. For every type of these solid acid catalysts, several materials were found that show high yield and selectivity to phenol. In this mini-review, first a brief introduction and overview on the Hock process is given. Next, the mechanism, kinetics, and safety aspects are summarized and discussed. Following, the different types of heterogeneous catalysts and their performance as catalyst in the Hock process are illustrated. Finally, the different approaches to substitute sulfuric acid in the synthetic route to produce phenol are briefly concluded and a short outlook is given.

2020 ◽  
Vol 15 (1) ◽  
pp. 199-212
Author(s):  
Fang Hou ◽  
Wei Zheng ◽  
Nasser Yousefi

Eco-friendly and reusable solid acid catalysts (SCMNPs@PC/VB1-Zn) were identified as one of the most effective basic catalysts for the composition of a pot, three-component pyrano[2,3-c]pyrazoles. Methyl-1-phenyl-1H-pyrazole-5(4H)-one, benzaldehyde and malononitrile in high yield at 80 °C. SCMNPs@ PC/VB1-Zn reports the simple and efficient catalysis of a three-component pot reaction of dimedone, aldehydes, and malononitrile to 4H-benzo-[b]-pyran derivatives. This magnetic nanocatalyst can be recycled more than 6 times without dramatically reducing performance with respect to reaction time and efficiency. Copyright © 2020 BCREC Group. All rights reserved


Synthesis ◽  
2021 ◽  
Author(s):  
Ken-ichi Itoh ◽  
Mamiko Hayakawa ◽  
Rina Abe ◽  
Shinji Takahashi ◽  
Kenta Hasegawa ◽  
...  

Nitrile oxides were obtained from α-nitro ketones by the use of silica-gel supported sodium hydrogensulfate (NaHSO4/SiO2) or Amberlyst 15 as solid acid catalyst, and then the corresponding 3-acylisoxaszoles were obtained from alkynes via the 1,3-dipolar ([3+2]) cycloaddition. These heterogeneous catalysts are easily separable from the reaction mixture, and reused up to the synthesis. This synthetic method provides a facile, efficient and reusable production of 3-acylisoxazoles.


Author(s):  
Nurul Aina Nasriqah Binti Ma’arof ◽  
Noor Hindryawati ◽  
Siti Norhafiza Mohd Khazaai ◽  
Prakash Bhuyar ◽  
Mohd Hasbi Ab. Rahim ◽  
...  

Biodiesel, an environmentally friendly biomass-based fuel, is gaining popularity globally as a cost-effective way to meet rising fuel demand. However, the high cost of raw materials and catalysts continues to drive up biodiesel production. An alternative feedstock with a heterogeneously catalyzed reaction could be the most cost-effective way to stabilize industrial biodiesel growth. Understanding these issues led to the idea of using waste palm oil as a feedstock for biodiesel production. While using waste materials as feedstock for biodiesel is an elegant solution, converting high free fatty acids (FFA) directly into methyl esters has some drawbacks. High FFA processes (acid esterification, then base transesterification) are costly. The commercial processes currently use a homogeneous system with sulfuric acid to catalyze both esterification and transesterification. However, heterogeneous solid acid catalysts are preferred over hazardous mineral acids for high FFA esterification because they are less corrosive, produce less waste, and are easier to separate from reactants and products by filtration, recovery, and reusability. Heterogeneous acid catalysts can also simultaneously catalyze transesterification and esterification reactions. Thus, new waste-based support for heterogeneous catalysts (solid acid catalysts) is required to convert waste oils into biodiesel.


2021 ◽  
Author(s):  
Amit Pramanik ◽  
Sanjay Bhar

Abstract: The –SO3H functionalized silica and alumina have emerged as efficient and eco-compatible heterogeneous solid acid catalysts for the construction of various important molecular skeletons. The advantages of –SO3H functionalized...


2017 ◽  
Vol 25 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Abd El Rahman S. Khder ◽  
Saleh A. Ahmed ◽  
Khalid S. Khairou ◽  
Hatem M. Altass

2014 ◽  
Vol 16 (12) ◽  
pp. 5465-5474 ◽  
Author(s):  
Jan P. Hofmann ◽  
Marcus Rohnke ◽  
Bert M. Weckhuysen

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is used for the characterization of heterogeneous catalysts. Large zeolite ZSM-5 crystals are discussed as a showcase system for solid acid catalysts and studied in high-resolution mass spectrometry, imaging, and sputter-depth profiling modes.


1992 ◽  
Vol 57 (11) ◽  
pp. 2241-2247 ◽  
Author(s):  
Tomáš Hochmann ◽  
Karel Setínek

Solid acid catalysts with acid strength of -14.52 < H0 < -8.2 were prepared by sulfate treatment of the samples of boehmite calcined at 105-800 °C. Two preparation methods were used: impregnation of the calcined boehmite with 3.5 M H2SO4 or mixing of the boehmite samples with anhydrous aluminum sulfate, in both cases followed by calcination in nitrogen at 650 °C. The catalysts were characterized by measurements of surface area, adsorption of pyridine and benzene, acid strength measurements by the indicator method and by catalytic activity tests in the isomerization of cyclohexene, p-xylene and n-hexane. Properties of the catalysts prepared by both methods were comparable.


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