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Khokarale, Santosh G.ORCID iD iconorcid.org/0000-0003-1901-6961
Publications (8 of 8) Show all publications
Khokarale, S. G. & Mikkola, J.-P. (2019). Efficient and catalyst free synthesis of acrylic plastic precursors: methyl propionate and methyl methacrylate synthesis through reversible CO2 capture. Green Chemistry, 21, 2138-2147
Open this publication in new window or tab >>Efficient and catalyst free synthesis of acrylic plastic precursors: methyl propionate and methyl methacrylate synthesis through reversible CO2 capture
2019 (English)In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 21, p. 2138-2147Article in journal (Refereed) Published
Abstract [en]

Methyl propionate (MP) and methyl methacrylate (MMA) are considered as industrially important precursors upon large-scale acrylic plastic production. The existing industrial synthetic protocols of these precursors utilize expensive catalysts accompanied with toxic and explosive gases such as carbon monoxide, ethylene and hydrogen. Herein, we for the first time report highly selective, catalyst-free and room temperature synthesis of MP and MMA precursors through organic superbase involved reversible CO2 capture approach. In short, initially equimolar mixture of organic superbase 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) and methanol were reversibly reacted with molecular CO2 and the obtained switchable ionic liquid, [DBUH][MeCO3] further reacted with an equivalent amount of propionic anhydride or methacrylic anhydride to form MP or MMA, respectively. These reactions were accomplished in different solvents such as DMSO and methanol whereupon, in case of methanol, separation of reaction products occurs from in-situ formed DBU derivatives such as [DBU][propionate] or [DBU][methacrylate]. In case of both MP and MMA synthesis, after use of methanol as a solvent, good recovery of alcoholic solution of esters were achieved where 85% and 92% yields of MP and MMA were obtained, respectively.The molecular DBU was recovered using NaCl saturated alkaline solution. Further, the recovered MMA with methanol was polymerised to poly-MMA using a benzoyl peroxide induced free radical polymerisation process. The synthesis and separation of MP or MMA as well as recovery of DBU was monitored by NMR analysis. Hence, unlike DMSO, methanol not only performed as a regent in CO2 capture and as a solvent media in MP, MMA and poly-MMA synthesis but also assisted in the recovery of DBU from the reaction mixture. Most importantly, here we represented a more efficient, safer and single solvent based alternative synthetic approach for the synthesis of acrylic plastic precursors MP or MMA compared to existing industrial methods. Also, no toxic or expensive catalysts were required.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-157484 (URN)10.1039/C9GC00413K (DOI)000465398000029 ()
Projects
Bio4Energy
Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-08-29Bibliographically approved
Shukla, S. K., Khokarale, S. G., Bui, T. Q. & Mikkola, J.-P. (2019). Ionic Liquids: Potential Materials for Carbon Dioxide Capture and Utilization. Frontiers in Materials, 6, Article ID 42.
Open this publication in new window or tab >>Ionic Liquids: Potential Materials for Carbon Dioxide Capture and Utilization
2019 (English)In: Frontiers in Materials, ISSN 2296-8016, Vol. 6, article id 42Article, review/survey (Refereed) Published
Abstract [en]

The nonvolatility, structure-tunability and high CO2 uptake capacity render ionic liquids (ILs) the most exciting materials for the carbon dioxide (CO2) capture and fixation to value-added chemicals. The aim of this mini-review is to give a brief idea about the development of the potential ILs for CO2 capture, the mechanism involved in the CO2 binding and the application of ILs in the conversion of CO2 to useful chemicals. The mechanisms and nature of interactions in between IL-CO2 have been discussed in terms of the nature of cation, anion, presence of functional group and the extent of interaction between the components of ILs. The fixation of CO2 to linear and cyclic carbonates and electroreduction of CO2 to carbon-rich fuels in ILs has been accounted in detail. At the end, future challenges in terms of commercializing the ILs for CO2 capture and utilization technology are discussed.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2019
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-157480 (URN)10.3389/fmats.2019.00042 (DOI)000462456000001 ()
Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-04-12Bibliographically approved
Khokarale, S. G. & Mikkola, J.-P. (2019). Metal free synthesis of ethylene and propylene carbonate from alkylene halohydrin and CO2 at room temperature. RSC Advances, 9(58), 34023-34031
Open this publication in new window or tab >>Metal free synthesis of ethylene and propylene carbonate from alkylene halohydrin and CO2 at room temperature
2019 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 58, p. 34023-34031Article in journal (Refereed) Published
Abstract [en]

Herein we describe a metal free and one-pot pathway for the synthesis of industrially important cyclic carbonates such as ethylene carbonate (EC) and propylene carbonates (PC) from molecular CO2 under mild reaction conditions. In the actual synthesis, the alkylene halohydrins such as alkylene chloro- or bromo or iodohydrin and organic superbase, 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) reacted equivalently with CO2 at room temperature. The syntheses of cyclic carbonates were performed in DMSO as a solvent. Both 1,2 and 1,3 halohydrin precursors were converted into cyclic carbonates except 2-bromo- and iodoethanol, which were reacted equivalently with DBU through n-alkylation and formed corresponding n-alkylated DBU salts instead of forming cyclic carbonates. NMR analysis was used to identify the reaction components in the reaction mixture whereas this technique was also helpful in terms of understanding the reaction mechanism of cyclic carbonate formation. The mechanistic study based on the NMR analysis studies confirmed that prior to the formation of cyclic carbonate, a switchable ionic liquid (SIL) formed in situ from alkylene chlorohydrin, DBU and CO2. As a representative study, the synthesis of cyclic carbonates from 1,2 chlorohydrins was demonstrated where the synthesis was carried out using chlorohydrin as a solvent as well as a reagent. In this case, alkylene chlorohydrin as a solvent not only replaced DMSO in the synthesis but also facilitated an efficient separation of the reaction components from the reaction mixture. The EC or PC, [DBUH][Cl] as well as an excess of the alkylene chlorhydrin were separated from each other following solvent extraction and distillation approaches. In this process, with the applied reaction conditions, >90% yields of EC and PC were achieved. Meanwhile, DBU was recovered from in situ formed [DBUH][Cl] by using NaCl saturated alkaline solution. Most importantly here, we developed a metal free, industrially feasible CO2 capture and utilization approach to obtain EC and PC under mild reaction conditions.

Place, publisher, year, edition, pages
The Royal Society of Chemistry, 2019
National Category
Organic Chemistry Chemical Process Engineering Materials Chemistry Analytical Chemistry Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-164580 (URN)10.1039/C9RA06765E (DOI)000496137600058 ()
Projects
Bio4Energy
Funder
Swedish Research Council, 2016-04090Bio4EnergyThe Kempe FoundationsKnut and Alice Wallenberg Foundation
Available from: 2019-10-24 Created: 2019-10-24 Last updated: 2019-12-09Bibliographically approved
Mukesh, C., Khokarale, S. G., Virtanen, P. & Mikkola, J.-P. (2019). Rapid desorption of CO2 from deep eutectic solvents based on polyamines at lower temperatures: an alternative technology with industrial potential. Sustainable Energy & Fuels, 3(8), 2125-2134
Open this publication in new window or tab >>Rapid desorption of CO2 from deep eutectic solvents based on polyamines at lower temperatures: an alternative technology with industrial potential
2019 (English)In: Sustainable Energy & Fuels, ISSN 2398-4902, Vol. 3, no 8, p. 2125-2134Article in journal (Refereed) Published
Abstract [en]

Herein we developed a new family of polyamine-based deep eutectic solvents (DESs) dedicated to reduce the energy consumption, avoiding the formation of hazardous molecules, aiming at low solvent losses and robust desorption efficiency for carbon dioxide (CO 2) capture technology. The strategy developed for economical, thermally stable and low viscous absorbents for CO 2 capture by functionalized neoteric media of azolide anion and secondary amine is presented. The prepared anion functionalized ionic liquids (ILs) and the derived DESs with ethylene glycol (EG) have a low viscosity which promotes high uptake of CO 2 (17-22% w/w) at 298.15 K and 1 atm. The absorption capacity of DESs was determined by a gravimetric technique. 13 C NMR was used for examine the desorption efficiency (DE) of CO 2. It was found that rapid desorption of CO 2 in TEPA polyamine based DESs occurs compared to monoethanolamine at 80 °C. However, the desorption rate of CO 2 was observed to be higher at higher temperatures and, as a result, under nitrogen flow complete desorption of CO 2 took place at 100 and 110 °C after 30 and 20 minutes, respectively. Consequently, comparative regeneration of CO 2 was studied in the absence of nitrogen flow at different temperatures. Excellent reversible uptake of CO 2 was observed without significant loss of absorption capacity under four consecutive cycles at 100 °C. The chemisorption of CO 2 was verified by 13 C NMR, 2D-NMR and FT-IR spectroscopy. The solvent loss study demonstrated the low volatility of polyamines based DESs at 100 °C and 120 °C after 50 hrs. The proposed DESs are thermally stable, cheap and give rise to negligible amounts of hazardous degradation components. Further, they exhibit low solvent losses, low viscosities and rapid CO 2 desorption capability. Therefore they are promising candidates when aiming at improving amine based conventional CO 2 capture technology.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-161789 (URN)10.1039/C9SE00112C (DOI)000476912900021 ()2-s2.0-85069772826 (Scopus ID)
Projects
Bio4Energy
Available from: 2019-08-05 Created: 2019-08-05 Last updated: 2019-08-30Bibliographically approved
Khokarale, S. G. & Mikkola, J.-P. (2018). Hydrogen sulfide gas capture by organic superbase 1,8-diazabicyclo-[5.4.0]-undec-7-ene through salt formation: salt synthesis, characterization and application for CO2 capture. RSC Advances, 8(33), 18531-18541
Open this publication in new window or tab >>Hydrogen sulfide gas capture by organic superbase 1,8-diazabicyclo-[5.4.0]-undec-7-ene through salt formation: salt synthesis, characterization and application for CO2 capture
2018 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 33, p. 18531-18541Article in journal (Refereed) Published
Abstract [en]

Hydrogen sulfide (H2S) is a toxic and environment polluting gas like other acid gases and hence its capture and sequestration is equally important before release into the atmosphere. In this regard, solvent-based processes involving aqueous tertiary amine systems were extensively studied and used. Herein, in line with an analogous pathway, we report capture of H2S gas in the form of its salt with an organic superbase such as 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) and the obtained salt was thoroughly studied. Spectroscopic analyses such as NMR and FTIR analyses confirmed that the H2S molecule formed an ionic solid adduct with DBU through protonation of its sp2-hybridized N atom. The stability of formed [DBUH][SH] salt in aqueous solution as well as under thermal treatment was also studied and monitored by NMR and thermogravimetric analysis (TGA), respectively. In aqueous medium, compared to DBU, the [DBUH][SH] salt exhibited long term stability without decomposition whereas under thermal treatment both DBU and its salt with H2S turned out to be thermally unstable where salt showed a volatile nature like a sublimized solid. Dissolution feasibility of [DBUH][SH] salt was also compared with DBU in polar as well as non-polar solvents and even though the [DBUH][SH] salt had an ionic nature, like DBU, it was also found soluble in various polar and non-polar solvents. Considering the stability of [DBUH][SH] salt in aqueous medium, its aqueous solution was further explored as a solvent media for CO2 capture where the influence of process parameters such as the influence of concentration of water in the solvent and CO2 flow rate was studied. Most importantly, here we demonstrated the synthesis of [DBUH][SH] salt for easy capture of H2S gas following reaction with DBU under ambient reaction conditions.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-147956 (URN)10.1039/C8RA02993H (DOI)000433428300042000433428300042 ()
Projects
Bio4Energy
Funder
Swedish Research Council, 2016-04090Bio4EnergyThe Kempe FoundationsKnut and Alice Wallenberg Foundation
Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2019-08-29Bibliographically approved
Bui, T. Q., Khokarale, S. G., Shukla, S. K. & Mikkola, J.-P. (2018). Switchable Aqueous Pentaethylenehexamine System for CO2 Capture: an Alternative Technology with Industrial Potential. ACS Sustainable Chemistry & Engineering, 6(8), 10395-10407
Open this publication in new window or tab >>Switchable Aqueous Pentaethylenehexamine System for CO2 Capture: an Alternative Technology with Industrial Potential
2018 (English)In: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 6, no 8, p. 10395-10407Article in journal (Refereed) Published
Abstract [en]

Herein we report the application of polyamine pentaethylenehexamine (PEHA, 3,6,9,12-tetraazatetradecane-1,14-diamine) in CO2 absorption with both neat PEHA and aqueous solutions thereof. The absorption of molecular CO2 in pure PEHA and in PEHA-water systems resulted in the formation of two chemical species, namely, PEHA carbamate and bicarbonate. It was observed that, upon formation of these species, both the CO2 absorption capacity and CO2 absorption rate were controlled by the amount of water in the system. During the CO2 absorption, the neat PEHA and 92 wt % PEHA were capable of forming carbamate species only while other aqueous analogues with higher dilution allowed for the formation of both carbamate and bicarbonate species upon exceeding 8 wt % water in the mixture. The CO2 uptake steadily increased with an increase in the water concentration in the solvent mixture and reached the maximum value of 0.25 g of CO2/(g of solvent) in the case of 56 wt % PEHA in water. However, in the case of more dilute systems (i.e., <56 wt % PEHA in water), the trend reversed and the CO2 loading decreased linearly to 0.05 g of CO2/(g of solvent) for 11 wt % PEHA in water. Meanwhile, it usually took shorter time to achieve the full CO2 absorption capacity (equilibrium) with increasing water content in all cases. The C-13 NMR analysis was used to quantify the relative amount of PEHA carbamate and bicarbonate, respectively, in reaction mixtures. The Kamle-Taft parameters (alpha, beta, and pi*) of aqueous solutions for different concentrations of PEHA were also studied taking advantage of various solvatochromic dyes and correlated with the CO2 absorption capacity. The thermally induced switchable nature of CO2-saturated neat and aqueous PEHA solutions for transformation of ionic PEHA carbamate and bicarbonate moieties to molecular PEHA is also represented. A comparison between aqueous PEHA and aqueous monoethanolamine (industrial solvent) for CO2 capture is reported. Hence, most importantly, a switchable PEHA system is demonstrated for reversible CO2 absorption processes.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
aqueous pentaethylenehexamine, PEHA, reversible CO2 capture, carbamate, bicarbonate, kamlet- ft parameters, regeneration
National Category
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-151562 (URN)10.1021/acssuschemeng.8b01758 (DOI)000441475500094 ()
Projects
Bio4Energy
Funder
Swedish Research Council, 2016-04090Knut and Alice Wallenberg FoundationBio4EnergyThe Kempe Foundations
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2019-08-29Bibliographically approved
Khokarale, S. G., Anugwom, I., Mäki-Arvela, P., Virtanen, P. & Mikkola, J.-P. (2018). Switchable polarity liquids. In: Ali Eftekhari (Ed.), Polymerized ionic liquids: (pp. 143-179). London: Royal Society of Chemistry
Open this publication in new window or tab >>Switchable polarity liquids
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2018 (English)In: Polymerized ionic liquids / [ed] Ali Eftekhari, London: Royal Society of Chemistry, 2018, p. 143-179Chapter in book (Other academic)
Abstract [en]

In this chapter, the synthesis and characterization, as well as applications, of various types of switchable polarity solvents (SPSs) are summarized in order to unravel their composition and switchable nature. The polarity 'switch' between a molecular liquid and ionic species in the case of SPSs is described on the basis of interactions occurring for various types of organic bases or silylamines with acid gases such as CO2 or SO2 and in the absence or presence of alcohols. The chapter consists of two principal parts where the synthesis of SPS systems is described as a result of interaction of one or two molecular components with acid gases. The molecular liquids in two-component SPSs comprise organic superbases such as 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) or 1,1,3,3-tetramethylguanindine (TMG or its derivatives) and lower to higher alcohols or water or glycerol. The one-component system involves the use of silylamines for SPS synthesis. The change in the composition and polarity of the reaction mixture during the synthesis, as well as the switchable nature of these SPSs, is demonstrated by gravimetric, spectroscopic and conductivity measurements. In the second part, various applications of SPS systems are described along with how the special characteristics of SPSs can be utilized.

Place, publisher, year, edition, pages
London: Royal Society of Chemistry, 2018
Series
Smart materials, ISSN 2046-0066 ; 29
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-140745 (URN)10.1039/9781788010535-00143 (DOI)9781782629603 (ISBN)9781788010535 (ISBN)9781788012218 (ISBN)
Available from: 2017-10-18 Created: 2017-10-18 Last updated: 2018-12-12Bibliographically approved
Khokarale, S. G., Le-That, T. & Mikkola, J.-P. (2016). Carbohydrate Free Lignin: A Dissolution-Recovery Cycle of Sodium Lignosulfonate in a Switchable Ionic Liquid System. ACS Sustainable Chemistry and Engineering, 4(12), 7032-7040
Open this publication in new window or tab >>Carbohydrate Free Lignin: A Dissolution-Recovery Cycle of Sodium Lignosulfonate in a Switchable Ionic Liquid System
2016 (English)In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 4, no 12, p. 7032-7040Article in journal (Refereed) Published
Abstract [en]

In this work, carbohydrate free lignin wasobtained by treating a technical lignin such as sodiumlignosulfonate (SLS) with a switchable ionic liquid (SIL).The SIL was synthesized from molecular moieties such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), monoethanol amine(MEA), and carbon dioxide gas and characterized by1H,13C,and1H−13C two-dimensional heteronuclear multiple-bondcorrelation nuclear magnetic resonance (NMR) spectroscopy.The as-synthesized SIL was used as a solvent medium fordissolution of SLS-containing polysaccharide (e.g., glucan andxylan) impurities under various reaction conditions. Parame-ters such as dissolution time and temperature as well as theSLS concentration were varied. In a manner independent of the dissolution time and temperature, 2 g of SIL was able tocompletely dissolve 0.3 g of SLS and≈60% SLS was recovered upon precipitation with an ethanol/hexane antisolvent system.The nonrecovered SLS remained in the viscous SIL phase. However, the dissolution ability of the SIL steadily decreased withincreasing amounts of accumulated SLS. The recovered solids were analyzed by1H−13C two-dimensional heteronuclear single-quantum coherence NMR spectroscopy to elucidate the potential structural changes occurring in the SLS structure afterdissolution−recovery treatment in the SIL. It was observed that in all experiments, SIL demonstrated its ability to extract theinterlinked polysaccharide impurities from the SLS while the linkages and aromatic subunits remain unaffected during thedissolution−recovery cycle. Most importantly, here we describe that the SIL can be used as an affordable solvent medium (incomparison to typical commercially available ionic liquids) to obtain carbohydrate free lignin from an impure lignin source.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2016
Keywords
Switchable ionic liquids, Sodium lignosulfonate, Carbohydrate impurity, Lignin pretreatment, 2D NMR analysis
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-126880 (URN)10.1021/acssuschemeng.6b01927 (DOI)000389497900087 ()2-s2.0-85002170782 (Scopus ID)
Projects
Bio4Energy
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2019-08-29Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1901-6961

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