Ultrasonics Sonochemistry xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Ultrasonics Sonochemistry journal homepage: www.elsevier.com/locate/ultson
Misinterpretation of green chemistry q We would like to draw attention of the readers of this journal to a scientific error which is becoming problematic in the chemical literature – the misuse of the term ‘‘Green’’. A recent example of this is the paper published in Ultrasonics Sonochemistry entitled ‘‘Green condensation reaction of aromatic aldehydes with active methylene compounds catalyzed by anion-exchange resin under ultrasound irradiation’’ [1]. We will use this paper as an example to justify the points we are making not because it is a particularly bad example, but because it contains a number of the common errors that are to be found in papers that misuse the terms ‘‘green’’ or ‘‘sustainable’’. We believe that if author use these terms in a manuscript, particularly in the title or the keywords, then this must be justified in the manuscript itself and in the accompanying letter to the editor. The term ‘green’ in this [1] article encourages review of this article, as some readers are looking for the methodologies to make current products green. In particular, green chemistry aspects of the reaction were not discussed in the paper. The use of ‘ultrasonic activation’ was used to minimize the reaction time. Yet, the energy efficiencies of other existing processes were not compared with the data. In fact, required energy efficiency of ultrasound irradiation was not discussed. The role of ultrasonication sonochemistry [2] in the field of green chemistry has been proven through previously published studies [3]. Sono-catalytic degradation and ultrasound promoted organic synthesis [4,5] have been found to be green in nature. Experts in the fields of green chemistry defined [6–9] ‘green’ as ‘‘the products and processes that reduce or eliminate the use or generation of hazardous substances’’. The toxicity of the product a-cyanocinnamate is well known [10]. This article [1] focused on products that qualify as ‘hazardous’ substances. The first impression this article leaves the reader is that the a-cyanocinnamate products of interest are green-non-hazardous, but no explanation of the product’s green nature is provided. The hazards related to the catalyst resins, reactants and chemicals used in this reaction are also well identified through the product material safety data sheets (MSDS). The Ohio Department of Health, New Jersey Department of Health and Senior Services have noted the health hazards of benzaldehyde, which is a feedstock of the reaction in question. The life cycle assessment [11], safety and health issues of the product and the reaction are also not discussed in this article.
q From the Editor in Chief and regional Editors of Ultrasonics Sonochemistry. We would like to support the points made in this letter about the use of the term ‘‘Green’’ or ‘‘Sustainable’’ in any title, paper or keywords of manuscripts submitted to Ultrasonics Sonochemistry must be supported by a justification for its use in the manuscript itself and also in the supporting letter to the editor accompanying the submission.
http://dx.doi.org/10.1016/j.ultsonch.2015.04.007 1350-4177/Ó 2015 Elsevier B.V. All rights reserved.
Table 1 Comparison of green and sustainable chemistry terminologies [12–14]. Green chemistry
Sustainable chemistry
(1) Avoids toxic product generation (2) Pollutants are not tolerated
(1) Important toxic products could be produced (2) Pollutants tolerated in a sensible manner (3) Blends society benefit with environmental impacts (4) Broad focus includes yield, efficiency, economy, politics and people (5) Broader term: includes green chemistry (6) Risk is tolerated if accepted by people/politics
(3) Limited to environmental impacts (4) Focus on toxicity, health hazards, pollution prevention (5) Individual term (6) No risk tolerance
There is a growing concern [14–17] over using the specialized term ‘green’ without substantial evidence through experimental data. The United States Environmental Protection Agency (US EPA) clearly accepted that green chemistry involves the elimination of hazardous substances from process chemistry. Green chemistry is just one of the tools towards sustainable process and product development. Sustainable chemistry is another term emerging from the studies which focus on the chemicals that may be relatively unsafe, yet important for several applications. A brief comparison between ‘green chemistry’ and ‘sustainable chemistry’ terminologies is provided in Table 1. The work mentioned in this article [1] focuses on increasing product yield, ease of chemical reaction and other important points that relate more to sustainability than the elimination of toxic, unsafe products. Hence, in our opinion, it should be called ‘Sustainable reaction’ instead of green. Therefore, an important question about the aforementioned article is: ‘‘Why and how this reaction could be termed ‘green’?’’ The objective of this letter is to educate readers in proper ‘green’ and ‘sustainable’ terminology use in their publications and importance of reactant and product toxicity information. The reputation and proper categorization of ‘green’ and ‘sustainable’ terminologies may be maintained for this important field if their use and justification are more carefully considered.
References [1] H.B. Ammar, M. Chtourou, M.H. Frikha, M. Trabelsi, Green condensation reaction of aromatic aldehydes with active methylene compounds catalyzed by anion-exchange resin under ultrasound irradiation, Ultrason. Sonochem. 22 (2015) 559–564. [2] T.J. Mason, Sonochemistry and the environment–providing a ‘‘green’’ link between chemistry, physics and engineering, Ultrason. Sonochem. 14 (2007) 476–483.
2
/ Ultrasonics Sonochemistry xxx (2015) xxx–xxx
[3] R. Konwarh, S. Pramanik, D. Kalita, C.L. Mahanta, N. Karak, Ultrasonication – a complementary ‘green chemistry’ tool to biocatalysis: a laboratory-scale study of lycopene extraction, Ultrason. Sonochem. 19 (2012) 292–299. [4] S.H. Banitaba, J. Safari, S.D. Khalili, Ultrasound promoted one-pot synthesis of 2-amino-4, 8-dihydropyrano [3, 2-b] pyran-3-carbonitrile scaffolds in aqueous media: a complementary ‘green chemistry’ tool to organic synthesis, Ultrason. Sonochem. 20 (2013) 401–407. [5] S. Taherian, M.H. Entezari, N. Ghows, Sono-catalytic degradation and fast mineralization of p-chlorophenol: La 0.7 Sr 0.3 MnO 3 as a nano-magnetic green catalyst, Ultrason. Sonochem. 20 (2013) 1419–1427. [6] P.T. Anastas, J.C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, 2000. [7] A. Kleiner, What does it mean to be green?, Harv Bus. Rev. 69 (1991) 38–42. [8] P.T. Anastas, M.M. Kirchhoff, Origins, current status, and future challenges of green chemistry, Acc. Chem. Res. 35 (2002) 686–694. [9] E.J. Beckman, Supercritical and near-critical CO2 in green chemical synthesis and processing, J. Supercrit. Fluids 28 (2004) 121–191. [10] Y.E. Na, S. Kim, H. Bang, B. Kim, Y. Ahn, Fumigant toxicity of cassia and cinnamon oils and cinnamaldehyde and structurally related compounds to Dermanyssus gallinae (Acari: Dermanyssidae), Vet. Parasitol. 178 (2011) 324– 329. [11] C. Capello, U. Fischer, K. Hungerbühler, What is a green solvent? A comprehensive framework for the environmental assessment of solvents, Green Chem. 9 (2007) 927–934. [12] F. Cavani, G. Centi, S. Perathoner, F. Trifirò, Sustainable Industrial Chemistry: Principles, Tools and Industrial Examples, John Wiley & Sons, 2009.
[13] T. Collins, Essays on science and society. Toward sustainable chemistry, Science 291 (2001) 48–49. [14] N. Winterton, Chemistry for Sustainable Technologies: A Foundation, Royal Society of Chemistry, 2011. [15] S.L. Fegade, How green is the approach and chemical, Mater. Chem. Phys. 154 (2015) 176, http://dx.doi.org/10.1016/j.matchemphys.2015.01.041. [16] S.L. Fegade, Questionable green ionic liquid: comment on ‘‘extractive desulfurization of liquid fuels by energy efficient green thiazolium based ionic liquids’’, Ind. Eng. Chem. Res. 54 (2015) 2259, http://dx.doi.org/10.1021/ acs.iecr.5b00051. http://pubs.acs.org/doi/abs/10.1021/acs.iecr.5b00051. [17] S.L. Fegade, J.P. Trembly, Dispute over designating an Ionic Liquid as a Green Solvent, Chem. Eng. J. (2015), http://dx.doi.org/10.1016/j.cej.2015.03.103.
⇑
Swapnil L. Fegade Jason P. Trembly Ohio Coal Research Center, Russ College of Engineering and Technology, Ohio University, Athens, OH 45701, USA ⇑ Tel.: +1 740 593 0264; fax: +1 740 593 4902. E-mail address: [email protected] (S.L. Fegade) Available online xxxx
Contents lists available at ScienceDirect
Ultrasonics Sonochemistry journal homepage: www.elsevier.com/locate/ultson
Misinterpretation of green chemistry q We would like to draw attention of the readers of this journal to a scientific error which is becoming problematic in the chemical literature – the misuse of the term ‘‘Green’’. A recent example of this is the paper published in Ultrasonics Sonochemistry entitled ‘‘Green condensation reaction of aromatic aldehydes with active methylene compounds catalyzed by anion-exchange resin under ultrasound irradiation’’ [1]. We will use this paper as an example to justify the points we are making not because it is a particularly bad example, but because it contains a number of the common errors that are to be found in papers that misuse the terms ‘‘green’’ or ‘‘sustainable’’. We believe that if author use these terms in a manuscript, particularly in the title or the keywords, then this must be justified in the manuscript itself and in the accompanying letter to the editor. The term ‘green’ in this [1] article encourages review of this article, as some readers are looking for the methodologies to make current products green. In particular, green chemistry aspects of the reaction were not discussed in the paper. The use of ‘ultrasonic activation’ was used to minimize the reaction time. Yet, the energy efficiencies of other existing processes were not compared with the data. In fact, required energy efficiency of ultrasound irradiation was not discussed. The role of ultrasonication sonochemistry [2] in the field of green chemistry has been proven through previously published studies [3]. Sono-catalytic degradation and ultrasound promoted organic synthesis [4,5] have been found to be green in nature. Experts in the fields of green chemistry defined [6–9] ‘green’ as ‘‘the products and processes that reduce or eliminate the use or generation of hazardous substances’’. The toxicity of the product a-cyanocinnamate is well known [10]. This article [1] focused on products that qualify as ‘hazardous’ substances. The first impression this article leaves the reader is that the a-cyanocinnamate products of interest are green-non-hazardous, but no explanation of the product’s green nature is provided. The hazards related to the catalyst resins, reactants and chemicals used in this reaction are also well identified through the product material safety data sheets (MSDS). The Ohio Department of Health, New Jersey Department of Health and Senior Services have noted the health hazards of benzaldehyde, which is a feedstock of the reaction in question. The life cycle assessment [11], safety and health issues of the product and the reaction are also not discussed in this article.
q From the Editor in Chief and regional Editors of Ultrasonics Sonochemistry. We would like to support the points made in this letter about the use of the term ‘‘Green’’ or ‘‘Sustainable’’ in any title, paper or keywords of manuscripts submitted to Ultrasonics Sonochemistry must be supported by a justification for its use in the manuscript itself and also in the supporting letter to the editor accompanying the submission.
http://dx.doi.org/10.1016/j.ultsonch.2015.04.007 1350-4177/Ó 2015 Elsevier B.V. All rights reserved.
Table 1 Comparison of green and sustainable chemistry terminologies [12–14]. Green chemistry
Sustainable chemistry
(1) Avoids toxic product generation (2) Pollutants are not tolerated
(1) Important toxic products could be produced (2) Pollutants tolerated in a sensible manner (3) Blends society benefit with environmental impacts (4) Broad focus includes yield, efficiency, economy, politics and people (5) Broader term: includes green chemistry (6) Risk is tolerated if accepted by people/politics
(3) Limited to environmental impacts (4) Focus on toxicity, health hazards, pollution prevention (5) Individual term (6) No risk tolerance
There is a growing concern [14–17] over using the specialized term ‘green’ without substantial evidence through experimental data. The United States Environmental Protection Agency (US EPA) clearly accepted that green chemistry involves the elimination of hazardous substances from process chemistry. Green chemistry is just one of the tools towards sustainable process and product development. Sustainable chemistry is another term emerging from the studies which focus on the chemicals that may be relatively unsafe, yet important for several applications. A brief comparison between ‘green chemistry’ and ‘sustainable chemistry’ terminologies is provided in Table 1. The work mentioned in this article [1] focuses on increasing product yield, ease of chemical reaction and other important points that relate more to sustainability than the elimination of toxic, unsafe products. Hence, in our opinion, it should be called ‘Sustainable reaction’ instead of green. Therefore, an important question about the aforementioned article is: ‘‘Why and how this reaction could be termed ‘green’?’’ The objective of this letter is to educate readers in proper ‘green’ and ‘sustainable’ terminology use in their publications and importance of reactant and product toxicity information. The reputation and proper categorization of ‘green’ and ‘sustainable’ terminologies may be maintained for this important field if their use and justification are more carefully considered.
References [1] H.B. Ammar, M. Chtourou, M.H. Frikha, M. Trabelsi, Green condensation reaction of aromatic aldehydes with active methylene compounds catalyzed by anion-exchange resin under ultrasound irradiation, Ultrason. Sonochem. 22 (2015) 559–564. [2] T.J. Mason, Sonochemistry and the environment–providing a ‘‘green’’ link between chemistry, physics and engineering, Ultrason. Sonochem. 14 (2007) 476–483.
2
/ Ultrasonics Sonochemistry xxx (2015) xxx–xxx
[3] R. Konwarh, S. Pramanik, D. Kalita, C.L. Mahanta, N. Karak, Ultrasonication – a complementary ‘green chemistry’ tool to biocatalysis: a laboratory-scale study of lycopene extraction, Ultrason. Sonochem. 19 (2012) 292–299. [4] S.H. Banitaba, J. Safari, S.D. Khalili, Ultrasound promoted one-pot synthesis of 2-amino-4, 8-dihydropyrano [3, 2-b] pyran-3-carbonitrile scaffolds in aqueous media: a complementary ‘green chemistry’ tool to organic synthesis, Ultrason. Sonochem. 20 (2013) 401–407. [5] S. Taherian, M.H. Entezari, N. Ghows, Sono-catalytic degradation and fast mineralization of p-chlorophenol: La 0.7 Sr 0.3 MnO 3 as a nano-magnetic green catalyst, Ultrason. Sonochem. 20 (2013) 1419–1427. [6] P.T. Anastas, J.C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, 2000. [7] A. Kleiner, What does it mean to be green?, Harv Bus. Rev. 69 (1991) 38–42. [8] P.T. Anastas, M.M. Kirchhoff, Origins, current status, and future challenges of green chemistry, Acc. Chem. Res. 35 (2002) 686–694. [9] E.J. Beckman, Supercritical and near-critical CO2 in green chemical synthesis and processing, J. Supercrit. Fluids 28 (2004) 121–191. [10] Y.E. Na, S. Kim, H. Bang, B. Kim, Y. Ahn, Fumigant toxicity of cassia and cinnamon oils and cinnamaldehyde and structurally related compounds to Dermanyssus gallinae (Acari: Dermanyssidae), Vet. Parasitol. 178 (2011) 324– 329. [11] C. Capello, U. Fischer, K. Hungerbühler, What is a green solvent? A comprehensive framework for the environmental assessment of solvents, Green Chem. 9 (2007) 927–934. [12] F. Cavani, G. Centi, S. Perathoner, F. Trifirò, Sustainable Industrial Chemistry: Principles, Tools and Industrial Examples, John Wiley & Sons, 2009.
[13] T. Collins, Essays on science and society. Toward sustainable chemistry, Science 291 (2001) 48–49. [14] N. Winterton, Chemistry for Sustainable Technologies: A Foundation, Royal Society of Chemistry, 2011. [15] S.L. Fegade, How green is the approach and chemical, Mater. Chem. Phys. 154 (2015) 176, http://dx.doi.org/10.1016/j.matchemphys.2015.01.041. [16] S.L. Fegade, Questionable green ionic liquid: comment on ‘‘extractive desulfurization of liquid fuels by energy efficient green thiazolium based ionic liquids’’, Ind. Eng. Chem. Res. 54 (2015) 2259, http://dx.doi.org/10.1021/ acs.iecr.5b00051. http://pubs.acs.org/doi/abs/10.1021/acs.iecr.5b00051. [17] S.L. Fegade, J.P. Trembly, Dispute over designating an Ionic Liquid as a Green Solvent, Chem. Eng. J. (2015), http://dx.doi.org/10.1016/j.cej.2015.03.103.
⇑
Swapnil L. Fegade Jason P. Trembly Ohio Coal Research Center, Russ College of Engineering and Technology, Ohio University, Athens, OH 45701, USA ⇑ Tel.: +1 740 593 0264; fax: +1 740 593 4902. E-mail address: [email protected] (S.L. Fegade) Available online xxxx
