The Production of Isophorone
Mariano D. Susman
Round 1
Reviewer 1 Report
The present manuscript represents a review on the production of isophorone as an industrially valuable chemical. It provides a general overview of IP production. It is generally well constructed, although it is advised to re-arrange the chapters into “Natural occurrence and properties” and then “Synthesis and applications”. Also, for the manuscript to be published, several additional major revisions are needed. These include:
1. The language is often insufficiently precise and inconsistent. This should be corrected. Some examples: abstract, l. 11: aldol self-condensation (not self-aldol condensation); “The paper gives an overview of the production of isophorone” (not “an overview of isophorone, the state-of-the-art”), inconsistent: “vapor phase” (abstract, l. 18), but “gas phase process” in chapter 4.2 or even “vapor/gas phase” in p.1, l. 39; for an “Annual Ace production”, the balance space (World, Europe) should be given, also the unit would be “Mio Tons/year”, not “Mio Tons”, on p. 1, l. 10, the unit is “t/y” – and use SI units!)
2. The abstract should be condensed avoiding general statements such as the last sentence.
3. In what respect does this review differ from (p. 1, l. 27-28) beyond being more “up-to-date”?
4. Please clearly mention what the “importance” of the products from IP is based on (p. 2, l. 74-75).
5. The caption of Fig. 1 should be revised as now values are given. “Products derived from IP” would be enough.
6. It is a widely spread misconception that the Hock process is mainly for phenol production with acetone as a by-product. Depending on the market situation, it may be as well the other way around and acetone is the major product with phenol as a by-product. Therefore, p. 3, l. 96-97, should be corrected.
7. The role of the catalyst (p. 5, l. 104-109, chapter 5) should be clarified. Is it proven that the mentioned chemicals, especially the bases, are not converted stoichiometrically (and are not catalysts)
8. The text of chapters 5.1 and 5.2 should be condensed considering the information (already) given in Table 2 and 3, respectively.
9. The conclusions are too lengthy and read more like a summary. Instead, the general significance of the review for the filed should be emphasized.
Author Response
please see attached pdf
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors of this publication present an up to date review of the production of isophorone, describing fundamentals, as well as mechanistic and industrial production strategies currently implemented industrially or under evaluation, particularly liquid- and gas-phase processes.
The manuscript is comprehensive, presenting multiple recent references and is amenable to read, which makes it suitable for publication in Encyclopedia.
The following minor comments presented by this reviewer would further improve the readability and presentation quality:
1) In abstract, line 9, better to use the term “high-boiling-point solvent”
2) In multiple parts of the text commas are missing, for instance, in lines 10, 34, 82, 90, 92, 132, 265, 279, etc.
3) In line 25, please write Herle (Germany) as there is another place with the same name in Belgium.
4) In line 35, replace “its capability to be synthesized” by “the possibility of being synthesized”.
5) In line 37, better replace “Mio. Tons” to SI units, either Tg or just millions of tonnes or similar.
6) From the manuscript is unclear whether gamma-isophorone is actually an existing compound. It does not appear in Figure 3, nor physical properties are available, but it has a CAS number. If applicable, a clarifying sentence could be added indicating whether it is thermodynamically much less stable than the other isomers, so it is not commonly observed nor has been isolated, etc. In line 148, is not shown to form either.
Such brief discussion could apply also to the isomers of mesityl oxide.
7) In line 74, invert the order to “… the combat agent EA 1511 (P10), and the UV filter homosalate (P11)”, to match the order of the codes.
8) In line 74, it is mentioned “The most important products are… IPDA and IPDI”. Could authors qualitative indicate what measure of importance it is being used? Is there information of at which scales these are produced, or anything that would support the claimed importance?
9) In line 82, it is mentioned that IP can be used as a platform to produce renewable fuels, like “bio-based cycloalkanes for sustainable jet fuels”. What does this mean? Later authors state that IP is mainly produced industrially by the liquid-phase method, which is not a biological production process, and contradicts that notion.
10) The term “plant- and animal-derived products” in line 87 seems unnecessary. If IP occurs in plants and animals, as previously indicated, it would be directly expected IP to appear in their derived products.
11) In paragraph from lines 100 to 109, the use of the term “phorones” is somewhat confusing. In lines 102 and 108 they do not seem to have the same meaning. Compound (7), per se, is also termed phorone, so in line 108 using “…, phorones, isophorones,…” it is or redundant for isophorone or unclear.
12) Mesityl oxide abbreviation (as MO) could be introduced in line 106. That abbreviation is used in Figure 3, but has not been introduced in the main text.
13) In line 148, given the context, it is confusing if “Isophorone can react to…” refers to alpha, or both alpha and beta.
14) Flip formulas of compounds (16) and (17) upside-down, in Figure 3, to match with the rest of the molecular descriptions.
15) In Figure 3, the arrow connecting (11) and (10) may more suitably be a series of arrows, and not just a single full one, as it does not seem to involve a one-step process. In the caption, the term “self-aldol” term may be removed as not all steps involve aldol condensations.
16) Line 171, replace “doubled to 2000” by “doubled by 2000”.
17) Line 261, the starting “with” should be removed.
18) Caption of Figure 6 repeats derivates multiple times, which could be simplified.
19) In lines 309 and 377, replace “chapter” by “section”.
20) First column of tables 2 and 3 are unnecessary, remove.
21) In some part of the text it may worth clarifying if catalyst % refers to wt%.
22) In lines 339-347, are the pore sizes 0.315 mm (units see large for common pore dimensions) and the formula Mg1.0AlO correct? The latter does not seem to be balanced.
23) The paragraph comprising lines 349 to 361 pretty much repeats what already appears in table 3. It seems to just be duplicating the information. Simplify.
24) In line 390, the word “already” is redundant.
25) In line 419 it should read “processes” and “and/or” .
Author Response
please see attached pdf
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have made a significant effort to imrpove theier manuscript. Most of the issues raised in the review are now sufficiently addressed. Besides some language checks, tha manuscrript can now be recommended for publication.
Author Response
Dear reviewer, thank you for the fast editing of the manuscript!
We downloaded the latest version of the manuscript and, for the sake of clarity,
adopted all changes made therein. We then went through the cleaned
manuscript sentence by sentence and corrected the language issues.
We have uploaded the revised manuscript again.
Yours sincerely, Matthias Eisenacher
