A Comprehensive Review of Fine Chemical Production Using Metal-Modified and Acidic Microporous and Mesoporous Catalytic Materials
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe present review on the production of fine chemicals using microporous and mesoporous heterogeneous catalysts essentially constitutes a literature review, an aspect not explicitly mentioned in the manuscript's title. While the central theme of microporous and mesoporous materials is clearly outlined, the manuscript lacks tangible elements, such as figures or tables, to visually represent significant aspects within the core subject.
I am inclined to recommend against accepting this manuscript for publication, primarily due to the absence of a timeline that would illustrate the evolution of various catalysts utilized in the synthesis of fine chemicals, the involved reaction mechanisms, correlations between structure and properties with different solids evaluated, and other essential aspects. Incorporating such visual aids would greatly enhance the manuscript's clarity and impact.
Furthermore, considering the relatively low number of reviews dedicated to “fine chemicals/heterogeneous catalysis” (approximately 268 reviews according to Scopus), this review should have delved more deeply into the use of meso- and microporous materials to captivate the interest of readers and exploit the niche more effectively.
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Reviewer 2 Report
Comments and Suggestions for AuthorsThis review article summarizes microporous and mesoporous catalysts such as mesoporous silica, zeolites, and metal-organic frameworks (MOFs) for organic syntheses. The topic is timely, but no figures/tables/schemes are given, so it is too hard to understand it. Reaction schemes must be added. I would like to see a general guideline as a figure to understand how applicable reactions change when the type and pore size of porous materials change. In principle, I think this paper can be accepted after major revision. Other comments are listed below.
1) In p. 3, line 120, an ideal catalysts is high TON and TOF under room temperature. However, in industry, operating reactions at room temperature needs to cool the reactor and controlling the reaction temperature is rather difficult, which needs high cost. Please consider it again.
2) In the section 2.4.2., post-synthesis grafting and co-condensation method were explained for mesoporous organosilica. To give the schematic illustration is strongly recommended. When organometal complexes are immobilized in the pores, the examples of the complexes should be shown in figures. Classification of mesoporous silica, MOFs, and zeolites by pore size, suitable reaction and/or molecular size, functions, etc. by figure or table is strongly recommended.
3) Porous silica, zeolites, and MOFs have been used for not only solid acid-base catalysts as themselves but also supports to metal confinement in the pores. For different purposes, the design and suitable pore size would be different, so that categorization is needed at first in introduction by showing tables or figures. MOFs have four categories such as, i) metals in the framework play the catalytic active sites; ii) solid acid or base catalysts; iii) confinement of metal clusters; iv) precursor of carbon-based catalysts. First, please categorize these features, and then discuss and show the examples of each topic with figures. For each type of catalysts, please show what type of reactions can be applied. The same applies to porous silica and zeolites.
4) In p. 9, zeolites are just listed, but please add more information such as porous structures, pore size, etc.
5) Reaction schemes must be shown in particular for non-common organic compounds such as monoterpenoid dioxinols.
6) Compound names frequently starts by capital letters but should start by small letters in the sentences, e.g., benzene.
7) In p. 11, line 552, the dehydrogenation of ethanol to acetaldehyde was introduced, but acetaldehyde is a bulk chemical. Sometimes bulk chemical reactions are explained, but please more focus on fine chemical syntheses. Methanol to olefin process is not fine chemical.
8) In p. 13, line 628-632, what type of reaction are you discussing?
9) In p. 13, line 636, they mentioned the production of hexadecane with isoeugenol. The production of these compounds from what? Please show the reaction mechanism and how the Lewis acid sites affect which reaction step.
10) In. p. 15, line 745, what is the reaction using MOF that can adsorb CO2? In the text, only CO2 adsorption property was mentioned.
11) In the latter part, the paper focused more on the explanation of porous materials, and no information on what type of the reactions can be applied to each porous material. For example, in p. 19, several preparation methods were introduced, but I could not understand what kind of reactions they are effective for.
12) In p. 16, polymer-supported catalysts section, no information whether the polymer-supported catalysts introduced here possesses porous structures or not. Even assuming that they have a porous structure, the authors did not explain how the porous structure affects the reaction.
13) In p. 17, 2.6 section, I think this section treats metal clusters confined in porous structures whereas the title does not explain it. Almost no information on the reaction applied was given. In the latter part of this section, bulk chemical (petroleum chemical) process is explained, not fine chemicals.
14) In p. 18, line 926, for the synthesis of florol, please explain the reason why NaOH treatment improved the catalytic performance by showing the reaction mechanism.
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Reviewer 3 Report
Comments and Suggestions for AuthorsIn this review article, Saha et al. explore the complex and wide-ranging field of microporous and mesoporous catalysts within the fine chemical industry, analyzing both their potential drawbacks and benefits as well as their feasibility when compared to newer, emerging catalysts. The paper is deemed suitable for publication with minor revisions.
1. It seems that there is no Figure in this review article. In the reviewer’s opinion, the addition of some Figures or Tables would be beneficial to help readers understand how microporous and mesoporous heterogeneous catalysts contribute to the production of fine chemicals.
2. In the context of the drawbacks of microporous and mesoporous heterogeneous catalysts for the production of fine chemicals, it is recommended to compare some reported works and include tables in the review article.
3. In the "Future Directions" section, the authors are required to summarize the current work and provide perspective on further developments to help readers, especially young scientists, understand or feel inspired.
Comments on the Quality of English LanguageThe quality of English is good.
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Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsI believe that the corrected version does not enhance the original manuscript. Additionally, the manuscript in question is a literature review, a detail that should have been indicated in its title. Therefore, I am not inclined to accept it for publication.
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Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript has been significantly revised, but still needs revision. Please see below.
1) Abbreviations should not be used without a formal name explanation, e.g. MSN in Table 1 and BDC in Table 2.
2) The authors added examples of the reactions catalyzed porous catalysts in tables. However, they frequently used trivial names, which are sometimes hard to understand the chemical structures. In addition, sometimes the explanation of what is the major product is unclear in tables. For example, in Table 1, “selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, hydrocinnamaldehyde, and hydrocinnamyl alcohol”. The authors mentioned “selective” but did not mention which is the major product. In Table 3, “phenol hydroxylation”: where OH group is substituted on the benzene ring? The product will change by the position of the OH group, such as catechol and hydroquinone. Regioselectivity of the products should be mentioned for benzene methylation and tert-butylation of toluene. For readability, reactions must be shown by chemical schemes.
3) In Figure 1, isopulegol (1) and benzaldehyde (2) react to obtain dioxinol (4) probably via the reaction between the OH group of (1) and the carbonyl carbon of (2), protonation of C=C bond to form carbocation, followed by attack of the carbocation by hemiacetal OH group of the intermediate. I cannot understand why the compound (3) is the intermediate. To form the compound (3), the C-O bond of benzaldehyde should be cleaved. Reversible rearrangement reaction of (4) to (3) might occur, but why (3) is formed before the formation of (4)? For this reaction, Ce composite derived from MCM-41 was used as a catalyst. However, the reason why mesoporous Ce composite structure showed superior activity was not given. What it the main reason for the higher activity than other catalysts?
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