Ultrasound-Assisted 1,3-Dipolar Cycloadditions Reaction Utilizing Ni-Mg-Fe LDH: A Green and Sustainable Perspective

Round 1

Reviewer 1 Report

Ultrasound-Assisted 1,3-Dipolar Cycloadditions Reaction Utilizing Ni Mg Fe LDH: A Green and Sustainable Perspective.

M. A. Salam, E. S. Imdadulhaq, A. N. Al-Romaizan, T. S. Saleh, M. M. M. Mostafa,

An ultrasound-assisted reaction catalyzed by layered double hydroxides is investigated and used for the green synthesis of novel pyrazoles. The authors present interesting and useful results. The characterization of the catalyst was thoroughly performed.

However, the work should be completed before publication and some additional experiments need to be performed (blank reaction, kinetics).

The blank reactions with both catalysts without ultrasound assistance are missing.

The reaction kinetics for at least one catalytic reaction should be investigated.

The catalyst activities are to be compared to alternative catalysts for similar or same reactions (under/without ultrasound assistance), already described in the literature. Yields

 

Introduction:

Recent reviews on LDH catalysis and ultrasound promoted catalytic reactions are missing.

The authors should explain the benefits of ultrasonication during the reactions

 

Experimental Part:

I cannot find the exact protocol for the preparation of the two LDH catalysts.

 

Catalyst characterization:

The specific surface should have been determined

 

References :

The journal abreviations are not in agreement with the author guidelines of the journal Catalysis.

 

Further comments:

The English has to be improved for rendering the manuscript more comprehensive.

Line 48: “Bronstedt acidic”

 

Author Response

Reviewer 1 comments:

An ultrasound-assisted reaction catalyzed by layered double hydroxides is investigated and used for the green synthesis of novel pyrazoles. The authors present interesting and useful results. The characterization of the catalyst was thoroughly performed.

However, the work should be completed before publication and some additional experiments need to be performed (blank reaction, kinetics).

1. The blank reactions with both catalysts without ultrasound assistance are missing.

Response:

Thank you for the reviewer comment, we already did this in which Table 3 included both catalysts without ultrasonic irradiations (Silent Conditions) [entry 2 and entry 3].

2. The reaction kinetics for at least one catalytic reaction should be investigated.

Response:

Thank you for the reviewer comment, we agree with the reviewer that a deep kinetic study is necessary, which is in our future plan. In the present study we are trying to reveal the role of catalyst and ultrasound irradiation in the 1,3 dipolar cycloaddition reactions. In the next anticipated paper we will go deeply in the mechanistic study, which deserves extra work and focusing experiments.

 

3. The catalyst activities are to be compared to alternative catalysts for similar or same reactions (under/without ultrasound assistance), already described in the literature. Yields

Response:

Thank you for the reviewer comment, as we referred that the similar reaction only described under microwave irradiation using Mg Al Hydrotalcite in solventless fashion [reference 26], consequently we tested some LDH derivatives in our presented work.

4. Introduction:

Recent reviews on LDH catalysis and ultrasound promoted catalytic reactions are missing.

The authors should explain the benefits of ultrasonication during the reactions

 Response:

Thank you for the reviewer comment, we added the recent reviews on LDH and ultrasound promoted catalytic reaction in the revised version.

 

5. Experimental Part:

I cannot find the exact protocol for the preparation of the two LDH catalysts.

 Response:

Thank you for the reviewer comment, the preparation protocol of the LDH catalysts is added in the revised version

6. Catalyst characterization:

We apology for the missing characterization techniques and catalyst preparation method. In the revised version this section was completed and highlighted in the Experimental section.

 

7. References:

The journal abbreviations are not in agreement with the author guidelines of the journal Catalysis.

Response:

Thank you for the reviewer comment, we revised the references according to the Journal guidelines and we testify the present version includes the references in the proper assortment.

Further comments:

The English has to be improved for rendering the manuscript more comprehensive.

Line 48: “Bronstedt acidic”

 Response:

Thank you for the reviewer comment, we revised all typo-errors and the English language are revised.

Author Response File: Author Response.docx

Reviewer 2 Report

1)      Include more information on the biological importance of pyrazole in the introduction section and cite more recent references.

2)      From Table 1, entry 1 catalyst play a role in product transformation, so the authors should explain more discussion on the catalyst's role in the transformation of 1,3-dipolar cycloadditions reaction.

3)      Should provide the data and discussion of the morphology analysis of the reported catalyst.

4) Why did the authors not perform the protic solvents while doing the optimized studies?

 

5)  The supporting information section should provide copies of 1H NMR and 13C NMR spectrums of all reported derivatives 5c and 5d.

 

Author Response

Reviewer 2

Comments and Suggestions for Authors

 

• Include more information on the biological importance of pyrazole in the introduction section and cite more recent references.

Response:

Thank you for the reviewer comment, we add the recent biological importance about the pyrazole in the introduction part and cited more recent references.

 

• From Table 1, entry 1 catalyst play a role in product transformation, so the authors should explain more discussion on the catalyst's role in the transformation of 1,3-dipolar cycloadditions reaction.

 Response:

Thank you for the reviewer comment. The superiority of the Ni-Mg-Fe LDH over other LDH used is accredit to the small crystallite size, large surface area and the mesoporous nature, which assist a greater number of reactants molecules to react efficiently on the basic centers of NiMgFe LDH catalyst. This part is highlighted in the text.

 

• Should provide the data and discussion of the morphology analysis of the reported catalyst.

Response:

Thank you for the reviewer comment, the necessary morphology analysis of the reported catalyst was added in the revised version.

 

• Why did the authors not perform the protic solvents while doing the optimized studies?

Response:

Thank you for the reviewer comment, Due to the non-polar nature of the transition state, 1,3-dipolar cycloadditions experience minimal solvent effects.

 

5)  The supporting information section should provide copies of 1H NMR and 13C NMR spectrums of all reported derivatives 5c and 5d.

 Response:

Thank you for the reviewer comment, we add the NMR copies for all synthesized compounds.

Author Response File: Author Response.docx

Reviewer 3 Report

In this manuscript, Professor Mostafa and coworkers reported a green and sustainable reaction to synthesis of novel pyrazoles. This protocol can obtain high yields pyrazole derivatives in a short reaction time using Ni-Mg–Fe LDH as catalyst in green solvent by ultrasound irradiation. Moreover, a plausible mechanism of this approach was also discussed and The NiMgFe LDH based catalyst was demonstrated excellent reusability.

Overall, this work is competent and does present elements of novelty compared to previous preliminary published work. Thus, this reviewer recommends its publication in Catalysts after the following points being satisfactory addressed.

(1) What is US? please write the proper name marking in the text (Scheme 1, Table 1, Scheme 2)

(2) Please describe reaction conditions for the synthesis of pyrazoles in detail marking in the text. we are confused the reaction conditions in Table 1 was different from Method A and Method B.

(3) Please directly describe the reaction mechanism with diagrams using the form of chemical reaction equation and do something to further prove.

(4) Please explain the effect of Temperature-Programmed Desorption and N₂ Physisorption Measurement in the text.

(5) in the conclusions part, the manuscript refer to “avoiding the disadvantages of solvent-free reactions”. We consider solvent-free system could a greener way in organic synthesis. Please explain the advantages of this reaction compared to previous published work using solvent-free system. For comparison, it can be written in the introduction part.

Author Response

Reviewer 3

In this manuscript, Professor Mostafa and coworkers reported a green and sustainable reaction to synthesis of novel pyrazoles. This protocol can obtain high yields pyrazole derivatives in a short reaction time using Ni-Mg–Fe LDH as catalyst in green solvent by ultrasound irradiation. Moreover, a plausible mechanism of this approach was also discussed and The NiMgFe LDH based catalyst was demonstrated excellent reusability. Overall, this work is competent and does present elements of novelty compared to previous preliminary published work. Thus, this reviewer recommends its publication in Catalysts after the following points being satisfactory addressed.

(1) What is US? please write the proper name marking in the text (Scheme 1, Table 1, Scheme 2)

 Response:

Thank you for the reviewer comment, US is the abbreviation of ultrasound we clarify this abbreviation in our manuscript.

 

(2) Please describe reaction conditions for the synthesis of pyrazoles in detail marking in the text. we are confused the reaction conditions in Table 1 was different from Method A and Method B.

 Response:

Thank you for the reviewer comment, reaction conditions in table 1 includes both method in which under Ultrasonic irradiation (US) is Method A, and Silent condition (Without ultrasonic irradiation) method B.

(3) Please directly describe the reaction mechanism with diagrams using the form of chemical reaction equation and do something to further prove.

 Response:

Thank you for the reviewer comment, the Mechanism is already putted in Scheme 1 Just we clarify the effect of Catalyst according to the previous reference 26 that cited in our manuscript.

 

(4) Please explain the effect of Temperature-Programmed Desorption and N₂ Physisorption Measurement in the text.

 Response:

 Thank you for the reviewer comment. CO₂ TPD measurement was used to study the basic properties of the synthesized catalysts. The data obtained was explained in the characterization section. The N₂ physisorption measurement was displayed in the characterization section. The obtained data from CO2 TPD and N₂ physisorption was useful to understand the role of the catalyst in the catalytic performance as the mesoporosity, large surface area with fair basic sites were responsible for the superiority of Ni-Mg-Fe LDH catalyst as explained in the catalysis section.

(5) in the conclusions part, the manuscript refers to “avoiding the disadvantages of solvent-free reactions”. We consider solvent-free system could a greener way in organic synthesis. Please explain the advantages of this reaction compared to previous published work using solvent-free system. For comparison, it can be written in the introduction part.

 Response:

Thank you for the reviewer comment, We accept that solvent free system is greener route in organic synthesis but it may suffer from some disadvantage in which we need to extract the formed product from system by dissolution in powerful solvent and ensure that desorption of all molecules from surface of catalyst used to avoid yield reduction.

Author Response File: Author Response.docx

Reviewer 4 Report

1.      The experimental procedures should contain actual weights.

2.      The quality of some of the figures is low. Please correct.

3.      The novelty of this work should be highlighted.

4.      This work should be compared with other similar works in literature.

5.      Language needs polishing. A lot of grammatical mistakes.

6.      All references should be checked carefully. The authors should use a uniform format for references.

7. Modify the introduction with new literature in order to show the importance of pyrazoles. Probably some of the most pertinent and best texts as useful reports in the field for referencing are the following: 10.22034/ecc.2021.284257.1173; 10.22034/ecc.2021.291144.1189.

Author Response

1. The experimental procedures should contain actual weights.

Response:

Thank you for the reviewer comment, the actual  weights were added in the current version of the mnuscript.

 

2. The quality of some of the figures is low. Please correct.

 Response:

Thank you for the reviewer comment, the quality of the figures was improved as much as we can and added to the revised version.

 

2. The novelty of this work should be highlighted.

Response:

Thank you for the reviewer comment, we highlighted the novelty of our work in conclusion part.

 

3. This work should be compared with other similar works in literature.

Response:

Thank you for the reviewer comment, as we work on synthesis of novel pyrazole derivatives so we just refer in our manuscript to reference 26 that cited in manuscript for similar work.

4. Language needs polishing. A lot of grammatical mistakes.

Response:

Thank you for the reviewer's comment, we revised all typo errors and the English language is revised.

 

5. All references should be checked carefully. The authors should use a uniform format for references.

Response:

Thank you for the reviewer comment. We revised all references.

7. Modify the introduction with new literature in order to show the importance of pyrazoles. Probably some of the most pertinent and best texts as useful reports in the field for reference are the following: 10.22034/ecc.2021.284257.1173;. 10.22034/ecc.2021.291144.1189

 Response:

Thank you for the reviewer's comment; we added recent literature and cited the mentioned references.

Author Response File: Author Response.docx

Reviewer 5 Report

Abdel Salam et al report the syntesis  and characterisation  of MgFeLDH and NiMgFeLDH. They were used as catalysts in the ultrasound-assisted elaboration of some  pyrazolic derivatives via a 1,3-dipolar cycloaddition reaction. The paper looks interesting. However there is some points to be addressed before accepting this paper for publication in "Catalysts".

 

1. The synthesis method of catalysts is missing in the experimental part.

2. The elemental analysis of catalysts and the pyrazolic derivatives is missing althought it is mentionned in the section "4.1. general".

3. In in the section "4.1. general" the used solvent was DMSO not CDCl3.

4. NMR spectra should also  be provided for 5c and 5d.

5. According to the figure 1, the degradation of NiMgFeLDH, begins at 64 °C. However, the synthesis of the pyrazolic derivatives was conducted at 80 °C.  The question is: has the catalyst kept its structure during the reaction? 

6. Authors was used the hazardous benzene. Why the have not used toluene instead?

 

 

Author Response

Reviewer 5

Abdel Salam et al report the syntesis  and characterisation  of MgFeLDH and NiMgFeLDH. They were used as catalysts in the ultrasound-assisted elaboration of some  pyrazolic derivatives via a 1,3-dipolar cycloaddition reaction. The paper looks interesting. However there is some points to be addressed before accepting this paper for publication in "Catalysts".

1. The synthesis method of catalysts is missing in the experimental part.

Response:

Thank you for the reviewer comment, we apology for the missing part of catalysts synthesis which is added in the experimental section of the revised version.

 

2. The elemental analysis of catalysts and the pyrazolic derivatives is missing although it is mentioned in the section "4.1. general".

Response:

Thank you for the reviewer comment. The elemental analysis of the catalysts and pyrazoles derivatives analysis were added in the revised version.

3. In in the section "4.1. general" the used solvent was DMSO not CDCl3.

 Response:

Thank you for the reviewer comment, we correct this error.

4. NMR spectra should also be provided for 5c and 5d.

 Response:

Thank you for the reviewer comment, we add all NMR spectra for all synthesized compounds.

5. According to the figure 1, the degradation of NiMgFeLDH, begins at 64 °C. However, the synthesis of the pyrazolic derivatives was conducted at 80 °C.  The question is: has the catalyst kept its structure during the reaction? 

 Response:

Thank you for the nice observation and the kind comment. As seen from the TGA of the as-synthesized dried LDH samples, the first weight loss is related to the physiosorbed water (hydrate the dried LDH sample) which starts at relatively low temperature. LDH was dried at 80^oC in a drier for 16 h during the preparation conditions, which is added in the revised version. This means that the catalyst is stable during the reaction conditions that carried out at 80^oC.

 

6. Authors was used the hazardous benzene. Why the have not used toluene instead?

 Response:

Thank you for the reviewer's comment. We used the hazardous benzene in a model reaction as many published work in literature was used previously, so just for comparing results, also the using of toluene, unfortunately, gave a lower yield than other solvents.

Author Response File: Author Response.docx