3-Methyl-1-phenyl-4-thioacetylpyrazol-5-one
Round 1
Reviewer 1 Report
The article by Shivachev B., Kurteva V. and others is devoted to the synthesis of pyrazolone thioacetyl derivative. The work is of interest in the use of this compound in the coordination chemistry of transition metals. In this context, the authors pertinently refer to the chemistry of the corresponding 1,3-diketones and acylpyrazolones. The synthesis of the substance is efficient and can be extended to a further series of similar compounds. The substance has been characterized by all available methods and there is no doubt about the correctness of the presented structure. An interesting fact is that the pyrazolone ring remains inert to fuctionalization by the hydroxy group. I recommend this work for publication in Molbank after minor modifications.
Line 64. Correct the "mas spectrum".
Scheme 1. The starting compound is listed in the hydroxy tautomeric form. However, in the title of the article the keto form (pyrazolone) is indicated. Perhaps on Scheme 1 to give two forms of keto- and hydroxy- for pyrazolone for clarity.
In the description of the XRD, the bond lengths in the assumed O,S-chelate unit should be added. Perhaps this will give insights into the nature of electron density delocalization. I mean C5-C4, C4-C6, C3-C4 bond values. It is also interesting to see the differences in the C5-O1, C6-S1 bonds.
Author Response
Thank you very much for the time you and the other associate Editors have devoted to handle this submission. We are very grateful to you and Reviewers for the help permitting us to improve significantly the manuscript quality.
All corrections in the manuscript, inserted according to the Reviewer’s recommendations, are inserted as Track Changes.
The answers to the Reviewer’s recommendations are listed bellow:
Reviewer 1
The article by Shivachev B., Kurteva V. and others is devoted to the synthesis of pyrazolone thioacetyl derivative. The work is of interest in the use of this compound in the coordination chemistry of transition metals. In this context, the authors pertinently refer to the chemistry of the corresponding 1,3-diketones and acylpyrazolones. The synthesis of the substance is efficient and can be extended to a further series of similar compounds. The substance has been characterized by all available methods and there is no doubt about the correctness of the presented structure. An interesting fact is that the pyrazolone ring remains inert to fuctionalization by the hydroxy group. I recommend this work for publication in Molbank after minor modifications.
Line 64. Correct the "mas spectrum".
It is corrected.
Scheme 1. The starting compound is listed in the hydroxy tautomeric form. However, in the title of the article the keto form (pyrazolone) is indicated. Perhaps on Scheme 1 to give two forms of keto- and hydroxy- for pyrazolone for clarity.
In fact, acylpyrazolones exist in much more than two forms. In our previous study (RSC Adv. 2015, 5, 73859-73867) we managed to isolate five different polymorphs including three desmotropes. These forms are often in equilibrium, but sometimes the equilibrium is shifted strongly towards one of the tautomers. Therefore, acylpyrazolone is the accepted title of this class of compounds independently on the tautomeric form. In our case, we observed enol form both in chloroform solution by NMR (OH at 14.440 ppm, C=S at 216.85 ppm, etc.) and in solid state by single crystal XDR. Nevertheless, we agree the keto form is also possible and thus, we inserted it on the Scheme and indicated that the equilibrium is strongly shifted towards the enol tautomer.
In the description of the XRD, the bond lengths in the assumed O,S-chelate unit should be added. Perhaps this will give insights into the nature of electron density delocalization. I mean C5-C4, C4-C6, C3-C4 bond values. It is also interesting to see the differences in the C5-O1, C6-S1 bonds.
A description and a comparison with literature data are inserted; lines 78-84 in the revised document.
Faithfully yours,
Prof. Dr. Vanya Kurteva
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This well-written manuscript reports the preparation of the 3-methyl-1-phenyl-4-thioacetylpyrazol-5-one in a one-single reaction step in high yield (94%). This compound has been properly characterised by authors.
The manuscript could be accepted after minor revisions as followings:
- - Could the authors include the chemical structure of Lawesson’s reagent on Scheme 1?
- - Have authors assayed this compound to clarify if it is really an effective ligand for metal isolation and separation? If so, they could mention it briefly in the main text.
- - A blank space is lost in reference 2 (between ‘paving the’ and ‘way’).
Author Response
Dear Prof. Huang,
Thank you very much for the time you and the other associate Editors have devoted to handle this submission. We are very grateful to you and Reviewers for the help permitting us to improve significantly the manuscript quality.
All corrections in the manuscript, inserted according to the Reviewer’s recommendations, are inserted as Track Changes.
The answers to the Reviewer’s recommendations are listed bellow:
Reviewer 2
This well-written manuscript reports the preparation of the 3-methyl-1-phenyl-4-thioacetylpyrazol-5-one in a one-single reaction step in high yield (94%). This compound has been properly characterised by authors.
The manuscript could be accepted after minor revisions as followings:
Could the authors include the chemical structure of Lawesson’s reagent on Scheme 1?
It is now inserted.
Have authors assayed this compound to clarify if it is really an effective ligand for metal isolation and separation? If so, they could mention it briefly in the main text.
That is exactly the reason we obtained this compound. The detailed experiments for the evaluation of its extraction ability and to compare with the corresponding O-analogue are in progress. If we obtain interesting results, hopefully, we plan to extend the series towards other members of the group.
A blank space is lost in reference 2 (between ‘paving the’ and ‘way’).
It is corrected.
Faithfully yours,
Prof. Dr. Vanya Kurteva
Author Response File: Author Response.pdf
