Platform Chemicals from Ethylene Glycol and Isobutene: Thermodynamics “Pays” for Biomass Valorisation and Acquires “Cashback”
Round 1
Reviewer 1 Report
The paper “Thermodynamics “pays” for biomass valorization and gets “cashback”: platform chemicals from ethylene glycol and isobutene” shows interesting experimental results. Although it does not deal with novel research, it is true that reliable practical and experimental thermodynamic results need to be obtained through a combination of empirical, experimental and quantum chemical methods.
Some issues should be amended before publication:
- Figure 2 shows equation 1 and 2. This does not make any sense. Choose either equation or figure to show this information.
- Some references are missing in the main text. Please, carefully double-check this issue and amend it where needed.
- “The combustion gases were analyzed for carbon monoxide (Dräger tubes) and unburnt carbon, neither of which could be detected.” Which is the measurement technique? How was this done?
- Table 1 and Table 2 are not clear in the present form. Please, rearrange some data for a better view of those. Please, include the information in the first rows in the main text or as subscript. It is confusing with the rest of the table.
- There is no conclusion section in this manuscript. Please, include a section with the main results and outcomes from your work.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Reviewer Comments from paper:
Re: Manuscript Number: Chemistry-2340902
Title: Thermodynamics “pays” for biomass valorization and gets “cashback”: platform chemicals from ethylene glycol and isobutene
This paper discusses the potential applications of ethylene glycol (EG) produced from biomass, particularly in the synthesis of mono- and di-tert-butyl ethers. Accurate thermodynamic data are crucial for optimizing the technology for these processes. The paper presents measurements of vapor pressures and combustion energies for these ethers, as well as vaporization enthalpies and enthalpies of formation. Thermodynamic data were obtained using methods based on the First and Second Laws of Thermodynamics and validated using structure-property correlations and quantum chemical calculations. The results were compared with literature data on alkylation of EG with isobutene, and thermodynamic functions of ethylene glycol tert-butyl ethers were derived. The energetics of alkylation were determined using both the "First Law" and "Second Law" methods and showed good agreement. Additionally, interesting findings related to the entropy of ethylene glycol tert-butyl ethers were discussed.
Reviewer:
General comments
• The paper is well-written, and the methodology aligns with standard procedures in the literature. The generated thermodynamic data is both relevant and novel.
• Some minor changes are needed for manuscript acceptance.
• Additional details are required to support the argument of biomass valorization and the significance of the thermodynamic properties on their usage in this context.
• A revised title is suggested that better reflects the importance and impact of this research.
Specific:
1. Page 7, second paragraph “…The parameters and fitted to the experimental vapour pressures were used to derive thermodynamic functions of vaporisation, as shown in the next section....”
Reviewer:
Statistical parameters from these fitted equations should be reported in the supplementary section and some comments should be made upon these figures.
2. Page 12, Table 9, footprint “…d Calculated as the difference between column 5 and 3 in this table......”
Reviewer: Why this value is calculated as in d for EGD and not for EGM (exp) or why this value was not determined experimentally (EGD)? Please explain.
3. Page 15, Figure 3 “…Figure 3. Temperature dependence of the thermodynamic equilibrium constants of the tert-butylation of ethylene glycol: Ka (1) for the reaction according to Equation (1) and. Ka (2) for the reaction according to Equation (2). Experimental data are from Chang et al [15]. Numerical data are compiled in Table S5 ....”
Reviewer: Description of captions in Figure 3 are both open circles for Ka (1) and Ka(2). One of them should be solid circles. Please correct!
4. Page 15, Table 10 “…Thermodynamic functions .and..mo of the reactions (1) and (2) in the liquid phase and....”
Reviewer: Could you please provide some comments about the Fitting results (R2) of each equation? Since some points are very close in these two equations.
5. Page 16, first paragraph “…The main focus of our thermochemical study was on the energetics of the reactions relevant for biomass valorization.…”
Reviewer: Please elaborate more on the relevance of the biomass valorization on the context of the reactions under study from the obtained thermochemical data results here presented to show a broader impact of the present research.
6. Page 17, first paragraph “…but subtracting the symmetry correction (R×ln..) from the direct G4 result brought the calculated and experimental values into agreement (see Table 11): …”
Reviewer: Any justification for this subtraction? Please elaborate.
7. Page 17, second paragraph “…So in this paper we paid attention for practical thermodynamic aspects of biomass valorization, but unexpectedly we come back and get cashback with theoretical aspects related to the entropy calculations of flexible molecules with large a number of free rotators.”
Reviewer: Not quite a good phrase (pay and cashback) Please rephrase.
8. Page 18, third paragraph “…combination of experimental, empirical and quantum chemical methods....”
Reviewer: An alternate suggested title for the present research can be: "Advancing Biomass Valorization: Integrating Experimental, Empirical, and Quantum Chemical Methods for Generating Thermodynamic Data towards a Chemical Platform from Ethylene Glycol and Isobutene"
Author Response
Please see the attachment
Author Response File: Author Response.pdf
