Shoko Suzuki, Hiroyuki Ito, S. Ishizuka, R. Nonaka, M. Noike, T. Kodama, K. Funaki, Mizuho Taguchi, Taisei Kagaya, Sayaka Sato, G. Redler, Y. Yokoyama*
In the field of organic syntheses, the development of environmentally friendly methods based on the concept of green chemistry has been always required. In response to this requirement, we reported solvent- and catalyst-free syntheses of imines using the pressure reduction technique as a key technology. We found that this reaction proceeded very rapidly in the initial stage, but its rate decreased with the passage of time. It was also found that the reaction of benzaldehyde with aniline had a specificity that the phase transition occurred. In this method, the desired imines could be obtained in good to excellent yields, but target compounds had to be given by purifications using organic solvents. Therefore, we tried to develop the perfect synthetic method of imine derivatives without organic or inorganic solvents. We selected two methods and took them into this investigation. One was exactly mixing (1:1, substance ratio) aldehydes and amines and the other was employing lower pressure (>0.1 mmHg, previous method: 1.0 mmHg) at the pressure reducing technique. When this improved synthetic method was performed, it was revealed that pure target imines were obtained in excellent yields without any purification.
{"title":"Perfect Solvent- and Catalyst-Free Syntheses of Imine Derivatives Using the Pressure Reduction Technique","authors":"Shoko Suzuki, Hiroyuki Ito, S. Ishizuka, R. Nonaka, M. Noike, T. Kodama, K. Funaki, Mizuho Taguchi, Taisei Kagaya, Sayaka Sato, G. Redler, Y. Yokoyama*","doi":"10.4236/gsc.2019.94008","DOIUrl":"https://doi.org/10.4236/gsc.2019.94008","url":null,"abstract":"In the field of organic syntheses, the development of environmentally \u0000friendly methods based on the concept of green chemistry has been always \u0000required. In response to this requirement, we reported solvent- and \u0000catalyst-free syntheses of imines using the pressure reduction technique as a \u0000key technology. We found that this reaction proceeded very rapidly in the \u0000initial stage, but its rate decreased with the passage of time. It was also \u0000found that the reaction of benzaldehyde with aniline had a specificity that the \u0000phase transition occurred. In this method, the desired imines could be obtained \u0000in good to excellent yields, but target compounds had to be given by \u0000purifications using organic solvents. Therefore, we tried to develop the \u0000perfect synthetic method of imine derivatives without organic or inorganic \u0000solvents. We selected two methods and took them into this investigation. One \u0000was exactly mixing (1:1, substance ratio) aldehydes and amines and the other \u0000was employing lower pressure (>0.1 mmHg, previous method: 1.0 mmHg) at the \u0000pressure reducing technique. When this improved synthetic method was performed, \u0000it was revealed that pure target imines were obtained in excellent yields \u0000without any purification.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85525655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tyler J. Rauwolf, Zhi Geng, Zachary P. Kinney, Jared Renfroe, Jack Roireau, Lauren Yep, R. Mohan
An efficient method for the conjugate addition of indoles to a variety of chalcones using BiBr3 in ethanol (190 proof) is reported. Products are isolated by a simple procedure that avoids an aqueous work up and extensive chromatography, thus minimizing waste. Bismuth (III) compounds are especially attractive from a green chemistry perspective because they are remarkably nontoxic, non-corrosive and relatively inexpensive.
{"title":"Conjugate Addition of Indoles to α,β-Unsaturated Ketones Using Bismuth (III) Bromide","authors":"Tyler J. Rauwolf, Zhi Geng, Zachary P. Kinney, Jared Renfroe, Jack Roireau, Lauren Yep, R. Mohan","doi":"10.4236/GSC.2019.93005","DOIUrl":"https://doi.org/10.4236/GSC.2019.93005","url":null,"abstract":"An efficient method for the conjugate addition of \u0000indoles to a variety of chalcones using BiBr3 in ethanol (190 proof) \u0000is reported. Products are isolated by a simple procedure that avoids an aqueous \u0000work up and extensive chromatography, thus minimizing waste. Bismuth (III) \u0000compounds are especially attractive from a \u0000green chemistry perspective because they are remarkably nontoxic, \u0000non-corrosive and relatively inexpensive.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77379095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many energy consuming countries have carried out research, development, demonstration, planning and deployment of coal-to-liquids (CTL) because of its ability to replace oil imports by converting coal resources into fuel. Among them, China and South Africa successfully had their CTL technology industrialized, while the United States did not. To understand the differences in the industrial development level, a comparative study is necessary. This paper compares the history, driver and policy of CTL industry in China, South Africa and United States, collates and discloses numbers of industry details for the first time. We figure out that the motivation, top level planning and policy consistency are the key indicators of the difference on the industrial development level. Among them, the key to the success of CTL industrialization in China and South Africa is the government’s strong and stable determination to improve energy security, which provides a stable top-level planning and robust policy support. The failure of CTL in United States is caused by the shift of policy attention after its energy security situation improved.
{"title":"A Comparative Study for the Development of Coal-to-Liquids Industries in China, South Africa and United States","authors":"Yiming Li, Changqing Li","doi":"10.4236/GSC.2019.93006","DOIUrl":"https://doi.org/10.4236/GSC.2019.93006","url":null,"abstract":"Many energy \u0000consuming countries have carried out research, development, demonstration, \u0000planning and deployment of coal-to-liquids (CTL) because of its ability to \u0000replace oil imports by converting coal resources into fuel. Among them, China \u0000and South Africa successfully had their CTL technology industrialized, while \u0000the United States did not. To understand the differences in the industrial development \u0000level, a comparative study is necessary. This paper compares the history, driver \u0000and policy of CTL industry in China, South Africa and United States, collates \u0000and discloses numbers of industry details for the first time. We figure out \u0000that the motivation, top level planning and policy consistency are the key \u0000indicators of the difference on the industrial development level. Among them, \u0000the key to the success of CTL industrialization in China and South Africa is \u0000the government’s strong and stable determination to improve energy security, \u0000which provides a stable top-level planning and robust policy support. The \u0000failure of CTL in United States is caused by the shift of policy attention after \u0000its energy security situation improved.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82686897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Valadares, S. F. Resende, I. M. F. Oliveira, R. Augusti
The present work evaluates the feasibility of using the raw material collected from discarded zinc-carbon batteries as heterogeneous catalyst to degrade the dye Indigo Carmine in an aqueous solution. Besides the evident environmental application, this work also presents an economic alternative for the production of new catalysts used to remediate polluted waters. For this, discarded carbon-zinc batteries were gathered, disassembled and their anodic paste collected. After acidic treatment and calcination at 500°C, characterization measurements, i.e. flame atomic absorption spectroscopy (FAAS), nitrogen sorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM), revealed that the so-obtained material consisted mainly of ZnMn2O4. This material acts as a heterogeneous catalyst in a Fenton-like process that degrades the dye Indigo Carmine in water. That is probably due to the presence of Mn(III) (manganese in the +3 oxidation state) in this material that triggers the decomposition of hydrogen peroxide (H2O2) to yield hydroxyl radicals (HO·). Moreover, direct infusion electrospray ionization coupled to high resolution mass spectrometry (ESI-HRMS) was employed to characterize the main by-products resulting from such degradation process. These initial results thus indicate that raw materials from waste batteries can therefore be potentially employed as efficient Fenton-like catalysts to degrade organic pollutants in an aqueous solution.
{"title":"Discarded Carbon-Zinc Batteries as Source of an Efficient Heterogeneous Fenton-Like Catalyst Employed to Degrade Organic Molecules in an Aqueous Medium","authors":"A. Valadares, S. F. Resende, I. M. F. Oliveira, R. Augusti","doi":"10.4236/GSC.2019.93007","DOIUrl":"https://doi.org/10.4236/GSC.2019.93007","url":null,"abstract":"The present work evaluates the feasibility of using the raw material \u0000collected from discarded zinc-carbon batteries as heterogeneous catalyst to \u0000degrade the dye Indigo Carmine in an aqueous solution. Besides the evident \u0000environmental application, this work also presents an economic alternative for \u0000the production of new catalysts used to remediate polluted waters. For this, \u0000discarded carbon-zinc batteries were gathered, disassembled and their anodic \u0000paste collected. After acidic treatment and calcination at 500°C, \u0000characterization measurements, i.e. flame atomic absorption spectroscopy (FAAS), nitrogen sorption, X-ray \u0000diffraction (XRD) and scanning electron microscopy (SEM), revealed that the \u0000so-obtained material consisted mainly of ZnMn2O4. This \u0000material acts as a heterogeneous catalyst in a Fenton-like process that degrades \u0000the dye Indigo Carmine in water. That is probably due to the presence of \u0000Mn(III) (manganese in the +3 oxidation state) in this material that triggers \u0000the decomposition of hydrogen peroxide (H2O2) to yield \u0000hydroxyl radicals (HO·). Moreover, \u0000direct infusion electrospray ionization coupled to high resolution mass \u0000spectrometry (ESI-HRMS) was employed to characterize the main by-products \u0000resulting from such degradation process. These initial results thus indicate \u0000that raw materials from waste batteries can therefore be potentially employed \u0000as efficient Fenton-like catalysts to degrade organic pollutants in an aqueous \u0000solution.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87254940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A green, rapid and facile method for synthesis of pure rutile TiO2 has been developed. Rutile TiO2 of high purity was synthesized by controlled hydrolysis of TiCl3 in aqueous medium at room temperature. Addition of nitric acid to TiCl3 greatly increased the rate of TiCl3 hydrolysis, crystallization and surface area of the prepared TiO2 powder. The phase obtained in this way was identified by X-ray diffraction. TiO2 synthesized by this method showed a unique flower-like assembly of nanotubes, very high surface area and high photocatalytic activity under visible light irradiation.
{"title":"A Rapid and Facile Synthesis Method for Nanosize Rutile Phase TiO2 with High Photocatalytic Activity","authors":"Priyanka P. Bidaye, J. Fernandes","doi":"10.4236/GSC.2019.92003","DOIUrl":"https://doi.org/10.4236/GSC.2019.92003","url":null,"abstract":"A green, rapid and facile method for synthesis of pure rutile TiO2 has been developed. Rutile TiO2 of high purity was synthesized by controlled hydrolysis of TiCl3 in aqueous medium at room temperature. Addition of nitric acid to TiCl3 greatly increased the rate of TiCl3 hydrolysis, crystallization and surface area of the prepared TiO2 powder. The phase obtained in this way was identified by X-ray diffraction. TiO2 synthesized by this method showed a unique flower-like assembly of nanotubes, very high surface area and high photocatalytic activity under visible light irradiation.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78123806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A sustainable four-step synthesis of soluble perylenophanes for applications as fluorescent optical functional materials is presented and even allows upscaling because of starting with technical bulk products. Thus, terminal alkenylnitriles were alkylated reduced to amines, condensed with perylenetetracarboxylic bisanhydride and cyclised to cyclophanes by means of double cross metathesis in yields until 69% of isolated dyes. The first metathesis by means of the second-generation Hoveyda-Grubbs-catalyst brings the remaining reactive olefinic groups close together favouring the ring-closure to the cyclophanes where the locked neighboring of chromophores in a skew arrangement induce strong exciton interactions. The latter cause an increased the Stokes’ separation by means of a moderate hypsochromic shift of light absorption and a stronger bathochromic shift of fluorescence. Various applications such as for lasers, photonics, solar collectors or in analytics are discussed.
{"title":"A Sustainable Preparation of Functional Perylenophanes by Domino Metathesis","authors":"H. Langhals, Maximilian Rauscher, P. Mayer","doi":"10.4236/GSC.2019.92004","DOIUrl":"https://doi.org/10.4236/GSC.2019.92004","url":null,"abstract":"A sustainable four-step synthesis of soluble perylenophanes for applications as fluorescent optical functional materials is presented and even allows upscaling because of starting with technical bulk products. Thus, terminal alkenylnitriles were alkylated reduced to amines, condensed with perylenetetracarboxylic bisanhydride and cyclised to cyclophanes by means of double cross metathesis in yields until 69% of isolated dyes. The first metathesis by means of the second-generation Hoveyda-Grubbs-catalyst brings the remaining reactive olefinic groups close together favouring the ring-closure to the cyclophanes where the locked neighboring of chromophores in a skew arrangement induce strong exciton interactions. The latter cause an increased the Stokes’ separation by means of a moderate hypsochromic shift of light absorption and a stronger bathochromic shift of fluorescence. Various applications such as for lasers, photonics, solar collectors or in analytics are discussed.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89923910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The interest of this conference is agricultural, environmental, bioenergetics, and sanitary. In that context, domestic, agricultural and industrial environments produce organic waste, which needs to be collected, selected, stored and recycled properly in order to avoid environmental pollution and promote agriculture. The green Industry proposed involves the conversion of natural, non-toxic organic waste in order to efficiently produce organic fertilizers for agriculture. These types of fertilizers from biological origin are suitable because they are not toxic for human and the environment. Enzymatic reactions described in this presentation concern mainly the hydrolysis of proteins, sugars and lipids, the acidification of intermediate products from hydrolysis, the formation of acetate, and the production of methane. In other words, this review is timely as it discusses for the chemical behavior or the reactivity of different functional groups to better understand the enzymatic catalysis in the transformations of residual proteins, carbohydrates, and lipids to generate biomethane and fertilizers. In the same perspective, this review is to enrich the documentation related to organic reactions catalyzed by enzymes, which occur in the anaerobic degradation of residual organic substances, with emphasis on the structures of organic compounds and reaction mechanisms. This will allow understanding the displacement of the electrons of a reactive entity rich in electrons to another reactive entity that is poor in electrons to form new bonds in products.
{"title":"Conference Paper: Green Industry Adapted to Recycling Needs of Lubumbashi City and Surrounding Areas in Democratic Republic of the Congo","authors":"T. M. Mwene-Mbeja","doi":"10.4236/GSC.2019.91002","DOIUrl":"https://doi.org/10.4236/GSC.2019.91002","url":null,"abstract":"The interest of this conference is agricultural, environmental, bioenergetics, and sanitary. In that context, domestic, agricultural and industrial environments produce organic waste, which needs to be collected, selected, stored and recycled properly in order to avoid environmental pollution and promote agriculture. The green Industry proposed involves the conversion of natural, non-toxic organic waste in order to efficiently produce organic fertilizers for agriculture. These types of fertilizers from biological origin are suitable because they are not toxic for human and the environment. Enzymatic reactions described in this presentation concern mainly the hydrolysis of proteins, sugars and lipids, the acidification of intermediate products from hydrolysis, the formation of acetate, and the production of methane. In other words, this review is timely as it discusses for the chemical behavior or the reactivity of different functional groups to better understand the enzymatic catalysis in the transformations of residual proteins, carbohydrates, and lipids to generate biomethane and fertilizers. In the same perspective, this review is to enrich the documentation related to organic reactions catalyzed by enzymes, which occur in the anaerobic degradation of residual organic substances, with emphasis on the structures of organic compounds and reaction mechanisms. This will allow understanding the displacement of the electrons of a reactive entity rich in electrons to another reactive entity that is poor in electrons to form new bonds in products.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85543068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ethyl ester biodiesel has been produced from a non-edible Jatropha curcas oil. Oil was extracted from the plant seed using n-hexane at 60°C and pretreated by alkaline refining process to reduce the free fatty acid level to less than 1%. Base-catalysed transesterification reaction with absolute ethanol using potassium hydroxide catalyst was adopted for the conversion. Various physicochemical properties of the refined Jatropha curcas oil were investigated. The ethyl ester biodiesel produced was characterised for its fuel properties such as specific gravity at 15°C, flash point, pour point, kinematic viscosity, cetane number, iodine value and higher heating value using American Society for Testing and Materials Standard Methods. The crude and refined Jatropha curcas oil yields were 58.16% and 52.5%. The physicochemical analysis revealed FFA, saponification value and peroxide value of refined Jatropha curcas oil to be 0.58 mg KOH/g, 159.9 and 1.92 m E/kg respectively. The fatty acid composition obtained from gas chromatography (GC) revealed that the oil contained 44.85% oleic acid as the dominant fatty acid, while Margaric 0.01% and Behenic 0.02% the least. The biodiesel yield was 57.6%, and its measured fuel properties conformed with ASTM 6751 and EN 14214 standards.
乙酯生物柴油是从一种不可食用的麻疯树油中生产出来的。采用60℃正己烷萃取法提取植物种子油，经碱性精制预处理，使游离脂肪酸含量降至1%以下。采用氢氧化钾催化剂与无水乙醇进行碱催化酯交换反应。研究了精制麻疯树油的各种理化性质。采用美国试验与材料标准方法，对生产的乙酯生物柴油的燃料性能进行了表征，如15°C时的比重、闪点、倾点、运动粘度、十六烷值、碘值和较高的热值。麻疯树粗、精油得率分别为58.16%和52.5%。理化分析表明，麻疯树油的FFA值为0.58 mg KOH/g，皂化值为159.9 m E/kg，过氧化值为1.92 m E/kg。气相色谱法测定其脂肪酸组成，油酸含量为44.85%，脂肪酸含量最少的是玛格丽脂(0.01%)和白原酸(0.02%)。生物柴油产率为57.6%，其燃料性能符合ASTM 6751和EN 14214标准。
{"title":"Production, Characterisation and Fatty Acid Composition of Jatropha curcas Biodiesel as a Viable Alternative to Conventional Diesel Fuel in Nigeria","authors":"A. Azeez, Adeyinka Olubunmi Fasakin, J. Orege","doi":"10.4236/GSC.2019.91001","DOIUrl":"https://doi.org/10.4236/GSC.2019.91001","url":null,"abstract":"Ethyl ester biodiesel has been produced from a non-edible Jatropha curcas oil. Oil was extracted from the plant seed using n-hexane at 60°C and pretreated by alkaline refining process to reduce the free fatty acid level to less than 1%. Base-catalysed transesterification reaction with absolute ethanol using potassium hydroxide catalyst was adopted for the conversion. Various physicochemical properties of the refined Jatropha curcas oil were investigated. The ethyl ester biodiesel produced was characterised for its fuel properties such as specific gravity at 15°C, flash point, pour point, kinematic viscosity, cetane number, iodine value and higher heating value using American Society for Testing and Materials Standard Methods. The crude and refined Jatropha curcas oil yields were 58.16% and 52.5%. The physicochemical analysis revealed FFA, saponification value and peroxide value of refined Jatropha curcas oil to be 0.58 mg KOH/g, 159.9 and 1.92 m E/kg respectively. The fatty acid composition obtained from gas chromatography (GC) revealed that the oil contained 44.85% oleic acid as the dominant fatty acid, while Margaric 0.01% and Behenic 0.02% the least. The biodiesel yield was 57.6%, and its measured fuel properties conformed with ASTM 6751 and EN 14214 standards.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86826850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ionic liquids (ILs) with 1,3-disubstituted imidazolium cations and the dimethyl phosphate (DMP) anion, as well as the chloride anion were prepared and characterized by 1H NMR spectra, chromatographic and titrimetric purity control, and determination of the moisture content and thermal stability. ILs with the DMP anion decompose only at temperatures above 240°C. These ILs were tested as both reaction media (solvents) and catalysts for the Knoevenagel condensation reaction. The impact of the most significant structure elements of ILs was evaluated for the rates and yields of the condensation reaction. IL anions have the greatest effect on the condensation reactions, and even the chloride anion has some catalytic effect on the Knoevenagel condensation. Side chains in the imidazolium cations influence the reaction course very little. The ability of the imidazolium cations to form hydrogen bonding with the transition state of the condensation reaction leads to a remarkable slowdown in the reaction rates.
{"title":"Different Influence of Structure Elements of Ionic Liquids on the Knoevenagel Condensation Reactions","authors":"S. Zeltkalne, A. Zicmanis","doi":"10.4236/GSC.2018.84022","DOIUrl":"https://doi.org/10.4236/GSC.2018.84022","url":null,"abstract":"Ionic liquids (ILs) with 1,3-disubstituted imidazolium cations and the dimethyl phosphate (DMP) anion, as well as the chloride anion were prepared and characterized by 1H NMR spectra, chromatographic and titrimetric purity control, and determination of the moisture content and thermal stability. ILs with the DMP anion decompose only at temperatures above 240°C. These ILs were tested as both reaction media (solvents) and catalysts for the Knoevenagel condensation reaction. The impact of the most significant structure elements of ILs was evaluated for the rates and yields of the condensation reaction. IL anions have the greatest effect on the condensation reactions, and even the chloride anion has some catalytic effect on the Knoevenagel condensation. Side chains in the imidazolium cations influence the reaction course very little. The ability of the imidazolium cations to form hydrogen bonding with the transition state of the condensation reaction leads to a remarkable slowdown in the reaction rates.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73625371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deviations from chemical parity (PV) were evaluated with the search for very small enantiomeric excesses in a racemate prepared from non chiral materials and were detected by means of the circular dichroism (CD). Thus, intensely light-absorbing perylenebiscarboximides were attached to axially chiral biphenyls for the amplification of CD effects by exciton interactions of the adjacent chromophores. A rapidly racemising system was applied for the exclusion of artifacts and compared with an analogous with locked chirally. A very slight enantiomeric excess was detected for the (M) enantiomer. Application of the method for other systems was suggested and relations to natural products discussed.
{"title":"A Concept for a Novel Test for Chemical Parity","authors":"H. Langhals, Oswald Krotz","doi":"10.4236/GSC.2018.84021","DOIUrl":"https://doi.org/10.4236/GSC.2018.84021","url":null,"abstract":"Deviations from chemical parity (PV) were evaluated with the search for very small enantiomeric excesses in a racemate prepared from non chiral materials and were detected by means of the circular dichroism (CD). Thus, intensely light-absorbing perylenebiscarboximides were attached to axially chiral biphenyls for the amplification of CD effects by exciton interactions of the adjacent chromophores. A rapidly racemising system was applied for the exclusion of artifacts and compared with an analogous with locked chirally. A very slight enantiomeric excess was detected for the (M) enantiomer. Application of the method for other systems was suggested and relations to natural products discussed.","PeriodicalId":12770,"journal":{"name":"Green and Sustainable Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73943878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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