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Journal articles on the topic 'Solvent free reaction'

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Published: 18 May 2024

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1

Heydari, Somayyeh, Davood Habibi, and Alireza Faraji. "A Green and Efficient Solvent- and Catalyst-Free Ultrasonic Dibenzylation Procedure." Chemistry & Chemical Technology 16, no. 1 (February 20, 2022): 126–32. http://dx.doi.org/10.23939/chcht16.01.126.

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A greener improvement was achieved for the synthesis of diverse N,N-dibenzylated compounds from the reaction of various aromatic amines with benzyl bromide using the ultrasound irradiation in solvent- and catalyst-free conditions. The dibenzylation reactions were carried out in different solvents and solvent-free conditions under ultrasound irradiation at various temperatures. The yields were very low in all applied solvents, while in the solvent-free condition and at room temperature, the yields were excellent. Due to obtaining the high reaction yields, the catalyst was not used.

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2

Aljuboori, Sahar Balkat, Nedaa Abdulhameed Abdulrahim, Shuhad Yassen, and Heba Hashim Khaleel. "Organic Synthesis under Solvent-free Condition (Green Chemistry): A Mini Literature Review." Al-Rafidain Journal of Medical Sciences ( ISSN: 2789-3219 ) 3 (December 17, 2022): 109–15. http://dx.doi.org/10.54133/ajms.v3i.94.

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Solvents are important components in the pharmaceutical and chemical industries, and they are increasingly being used in catalytic reactions. Solvents have a significant influence on the kinetics and thermodynamics of reactions, and they can significantly change product selectivity. Solvents can influence product selectivity, conversion rates, and reaction rates. However, solvents have received a lot of attention in the field of green chemistry. This is due to the large amount of solvent that is frequently used in a process or formulation, particularly during the purification steps. However, neither the solvent nor the active ingredient in a formulation is directly responsible for the reaction product's composition. Because these characteristics have little bearing on how well or quickly the system in which the solvent is applied works, it appears unnecessary to use toxic, combustible, or environmentally hazardous solvents. However, the beneficial properties of the solvent required for the application are strongly linked to these unfortunate side effects of solvent use. Distillation can be used to recover and purify solvents because they are volatile; however, this process can produce unwanted air pollutants and be hazardous to workers during exposure. .

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3

Karolczak, Stefan, Hugh A. Gillis, Gerald B. Porter, and David C. Walker. "Solvent-dependent rate constants of muonium atom reactions." Canadian Journal of Chemistry 81, no. 2 (February 1, 2003): 175–78. http://dx.doi.org/10.1139/v03-009.

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The rates of reaction of muonium atoms with solutes, ionic and organic, were studied in solvents of wildly differing polarities (water, methanol, and hexane) and their rate constants were compared, where possible. In these reactions which are those of a highly reactive atom, an isotope of hydrogen it transpires that the reaction rates are higher in solvents in which the solute is more soluble and muonium diffuses faster. This study leads to various kinetic-solvent-effect ratios and to the observation of the reaction of muonium with free radicals being among the fastest reactions recorded so far between two neutral species in solution.Key words: muonium atoms, kinetic isotope effects, solvent-dependent rates, non-aqueous solvents, muon spin rotation technique.

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4

Braga, Dario, Stefano Luca Giaffreda, Fabrizia Grepioni, Michele R. Chierotti, Roberto Gobetto, Giuseppe Palladino, and Marco Polito. "Solvent effect in a “solvent free” reaction." CrystEngComm 9, no. 10 (2007): 879. http://dx.doi.org/10.1039/b711983f.

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5

Away, Kenneth Charles West, and Zhu-Gen Lai. "Solvent effects on SN2 transition state structure. II: The effect of ion pairing on the solvent effect on transition state structure." Canadian Journal of Chemistry 67, no. 2 (February 1, 1989): 345–49. http://dx.doi.org/10.1139/v89-056.

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Identical secondary α-deuterium kinetic isotope effects (transition state structures) in the SN2 reaction between n-butyl chloride and a free thiophenoxide ion in aprotic and protic solvents confirm the validity of the Solvation Rule for SN2 Reactions. These isotope effects also suggest that hydrogen bonding from the solvent to the developing chloride ion in the SN2 transition state does not have a marked effect on the magnitude of the chlorine (leaving group) kinetic isotope effects. Unlike the free ion reactions, the secondary α-deuterium kinetic isotope effect (transition state structure) for the SN2 reaction between n-butyl chloride and the solvent-separated sodium thiophenoxide ion pair complex is strongly solvent dependent. These completely different responses to a change in solvent are rationalized by an extension to the Solvation Rule for SN2 Reactions. Finally, the loosest transition state in the reactions with the solvent-separated ion pair complex is found in the solvent with the smallest dielectric constant. Keywords: ion pairs, transition state, solvent effects, nucleophilic substitution, isotope effects.

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6

Miyamoto, Hisakazu, Shotaro Kanetaka, Koichi Tanaka, Kazuhiro Yoshizawa, Shinji Toyota, and Fumio Toda. "Solvent-Free Robinson Annelation Reaction." Chemistry Letters 29, no. 8 (August 2000): 888–89. http://dx.doi.org/10.1246/cl.2000.888.

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7

Zhou, Jinkui, and Thomas W. Swaddle. "Pressure effects and solvent dynamics in the electrochemical kinetics of the tris(hexafluoroacetylacetonato)ruthenium(III)/(II) couple in nonaqueous solvents." Canadian Journal of Chemistry 79, no. 5-6 (May 1, 2001): 841–47. http://dx.doi.org/10.1139/v00-184.

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Rate constants and reactant diffusion coefficients for the Ru(hfac)30/ electrode reaction have been measured at 25°C as functions of pressure (0-200 MPa) in acetone, acetonitrile, methanol, and propylene carbonate. In sharp contrast to the negative volumes of activation ΔVex found for the corresponding bimolecular self-exchange reaction in organic solvents, the volumes of activation ΔVel for the electrode reaction are markedly positive, ranging from 8 to 12 cm3 mol1. The volumes of activation ΔVdiff for reactant diffusion (which can be equated to the volume of activation ΔVvisc for viscous flow) range from 12 to 19 cm3 mol1. For the Debye solvents acetonitrile and acetone at least, ΔVel is given within the experimental uncertainty by ΔVdiff + (ΔVex/2). In this relation, the numerical value of ΔVdiff represents indirectly the dominant contribution of solvent dynamics (solvent friction) to ΔVel, and ΔVex/2 represents the pressure dependence of the free-energy barrier height for the electrode reaction. It is proposed that solvent friction is important in nonaqueous electrode processes but not in the corresponding bimolecular self-exchange reactions because the free-energy activation barrier is twice as high in the latter.Key words: electrode reaction kinetics, solvent dynamics, electron transfer mechanisms, pressure effects, volume of activation.

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8

Saikia, Monmi, and Jadab C. Sarma. "Baylis–Hillman reaction under solvent-free conditions — Remarkable rate acceleration and yield enhancement." Canadian Journal of Chemistry 88, no. 12 (December 2010): 1271–76. http://dx.doi.org/10.1139/v10-133.

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A simple and efficient method has been developed for remarkable rate acceleration and yield enhancement of the Baylis–Hillman reaction under solvent-free “neat conditions” and solvent-less isolation of products. Reaction of equimolar quantities of aldehyde and olefin in the presence of 20 mol% of DABCO under neat conditions affords the highest yield in most cases within the shortest reaction time, giving support to the mechanisms of proton transfer in protic and aprotic solvents. Solvent-free conditions are found to be especially fast, selective, and high yielding for aromatic aldehydes.

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9

Choudhuri, Khokan, Arkalekha Mandal, and Prasenjit Mal. "Aerial dioxygen activation vs. thiol–ene click reaction within a system." Chemical Communications 54, no. 30 (2018): 3759–62. http://dx.doi.org/10.1039/c8cc01359d.

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By choosing appropriate reaction systems using solvents with additives or solvent free neat conditions, any one of the Markovnikov or anti-Markovnikov selective thiol–ene click (TEC) reactions and the synthesis of β-hydroxysulfides via aerial dioxygen activation could be achieved exclusively in excellent yields.

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10

Anbu, Nagarjun, Jacob, Kalaiarasi, and Dhakshinamoorthy. "Acetylation of Alcohols, Amines, Phenols, Thiols under Catalyst and Solvent-Free Conditions." Chemistry 1, no. 1 (July 10, 2019): 69–79. http://dx.doi.org/10.3390/chemistry1010006.

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In the present study, an easy and an efficient approach is reported for the acetylation of alcohols, amines, phenols, and thiols under solvent- and catalyst-free conditions. The experimental conditions were milder than conventional methods and the reactions were completed in shorter reaction time. The examined substrates afforded higher yields of the acetylated products under the short reaction time. Comparison of this work with earlier reported procedures reveals that this method offers some advantages than with reported catalysts and solvents. The as-synthesized products were characterized by 1H-NMR and GC-MS techniques to ensure their purity and identity. In addition, a possible mechanism was also proposed for this reaction.

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11

Jicsinszky, László, and Giancarlo Cravotto. "Toward a Greener World—Cyclodextrin Derivatization by Mechanochemistry." Molecules 26, no. 17 (August 27, 2021): 5193. http://dx.doi.org/10.3390/molecules26175193.

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Cyclodextrin (CD) derivatives are a challenge, mainly due to solubility problems. In many cases, the synthesis of CD derivatives requires high-boiling solvents, whereas the product isolation from the aqueous methods often requires energy-intensive processes. Complex formation faces similar challenges in that it involves interacting materials with conflicting properties. However, many authors also refer to the formation of non-covalent bonds, such as the formation of inclusion complexes or metal–organic networks, as reactions or synthesis, which makes it difficult to classify the technical papers. In many cases, the solubility of both the starting material and the product in the same solvent differs significantly. The sweetest point of mechanochemistry is the reduced demand or complete elimination of solvents from the synthesis. The lack of solvents can make syntheses more economical and greener. The limited molecular movements in solid-state allow the preparation of CD derivatives, which are difficult to produce under solvent reaction conditions. A mechanochemical reaction generally has a higher reagent utilization rate. When the reaction yields a good guest co-product, solvent-free conditions can be slower than in solution conditions. Regioselective syntheses of per-6-amino and alkylthio-CD derivatives or insoluble cyclodextrin polymers and nanosponges are good examples of what a greener technology can offer through solvent-free reaction conditions. In the case of thiolated CD derivatives, the absence of solvents results in significant suppression of the thiol group oxidation, too. The insoluble polymer synthesis is also more efficient when using the same molar ratio of the reagents as the solution reaction. Solid reactants not only reduce the chance of hydrolysis of multifunctional reactants or side reactions, but the spatial proximity of macrocycles also reduces the length of the spacing formed by the crosslinker. The structure of insoluble polymers of the mechanochemical reactions generally is more compact, with fewer and shorter hydrophilic arms than the products of the solution reactions.

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12

Singh, Girija S. "Greener Approaches to Selected Asymmetric Addition Reactions Relevant to Drug Development." Current Organic Chemistry 25, no. 13 (September 2, 2021): 1497–522. http://dx.doi.org/10.2174/1385272825666210519100457.

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Asymmetric organic synthesis is of paramount importance in the development of drugs. Asymmetric addition reactions such as aldol reaction, Michael addition, and Mannich addition reactions are important carbon-carbon bond-forming reactions and have been employed in the synthesis of a broad range of biologically important molecules. Many of these reactions have been developed under solvent-free conditions or in greener solvents like water. Several reactions have been developed at room temperature or by using a non-conventional energy source such as microwave irradiation. Several greener catalysts have been developed for such reactions. The present review article discusses the application of green chemistry parameters in the development of selected asymmetric addition reactions leading to biologically important molecules during the last ten years. Asymmetric aldol reactions, asymmetric Michael reactions, and different asymmetric addition reactions involving imines such as Mannich reaction, aza-benzoin reaction, etc. in aqueous media or under solvent-free conditions have been reviewed. Application of different types of catalysts such as prolinamides, 1,2-diamines, polymer and magnetic nanoparticle-supported chiral catalysts is demonstrated.

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13

Raston, Colin L., and Janet L. Scott. "Chemoselective, solvent-free aldol condensation reaction." Green Chemistry 2, no. 2 (2000): 49–52. http://dx.doi.org/10.1039/a907688c.

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14

Cablewski, Teresa, Paul A. Gurr, Peter J. Pajalic, and Christopher R. Strauss. "A solvent-free Jacobs–Gould reaction." Green Chemistry 2, no. 1 (2000): 25–28. http://dx.doi.org/10.1039/a908606d.

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15

Phonchaiya, Sonthi, Bhinyo Panijpan, Shuleewan Rajviroongit, Joanne T. Blanchfield, and Tony Wright. "A Facile Solvent-Free Cannizzaro Reaction." Journal of Chemical Education 86, no. 1 (January 2009): 85. http://dx.doi.org/10.1021/ed086p85.

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16

Du, Rui, Liangliang Han, Zhongqiang Zhou, and Victor Borovkov. "Efficient Synthesis of Novel Quinolinone Derivatives via Catalyst-free Multicomponent Reaction." Letters in Organic Chemistry 17, no. 5 (April 28, 2020): 403–7. http://dx.doi.org/10.2174/1570178616666190828092728.

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The synthesis of 3-(aryl(piperidin-1-yl)methyl)-4-hydroxyquinolin-2(1H)-one derivatives via catalyst-free multicomponent reaction is described. The reaction of 4-hydroxyquinolin-2(1H)-one, piperidine, and 4-chlorobenzaldehyde was carried out in different solvents and under solvent-free conditions at room temperature. The best solvent in terms of the yield and reaction time was found to be dichloromethane. Most substituted benzaldehydes reacted with 4-hydroxyquinolin-2(1H)-one and piperidine to afford corresponding products in good-to-excellent yields. Aldehydes with electronwithdrawing groups were more reactive to exhibit higher reaction rates. However, 2-substituted benzaldehydes did not react with 4-hydroxyquinolin-2(1H)-one and piperidine under the reaction condition. Aldehydes bearing a hydroxyl group failed to produce the corresponding products.

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17

Sharghi, Hashem, and Reza Khalifeh. "Reaction on a solid surface — A simple, economical, and efficient Mannich reaction of azacrown ethers over graphite." Canadian Journal of Chemistry 86, no. 5 (May 1, 2008): 426–34. http://dx.doi.org/10.1139/v08-026.

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Graphite brings about a rapid Mannich reaction with a range of activated and unactivated phenolic compounds such as p-cresol and p-nitrophenol. The reactions are carried out with azacrown ether and paraformaldehyde in solvent-free conditions at 100 °C for 20–30 min. The graphite powder can be reused up to three times after simple washing with acetone.Key words: azacrown ether, lariat ether, graphite, solvent-free, Mannich reaction.

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18

Stolle, Achim, and Bernd Ondruschka. "Solvent-free reactions of alkynes in ball mills: It is definitely more than mixing." Pure and Applied Chemistry 83, no. 7 (April 30, 2011): 1343–49. http://dx.doi.org/10.1351/pac-con-10-09-26.

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This contribution presents two solvent-free reactions of terminal alkynes in ball mills: Pd-catalyzed Sonogashira cross-coupling and Cu-catalyzed homo-coupling (Glaser reaction). The results are compared to other solvent-free reaction protocols, which have been published up to date for those types of reactions. Reactions are assessed on the basis of reaction variables like type of catalyst and base or reaction time. Furthermore, performance-based parameters (yield, selectivity, turnover number, TON, and turnover frequency, TOF) are considered and evaluated. Findings from ball-milling experiments indicate that those processes are comparable to the energy entry by microwave irradiation with respect to reaction time and TOF.

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19

Lam, Solita, Yvonne Puplampu Dove, Adrienne Morris, Ayunna Epps, and Ghislain R. Mandouma. "Cross-Coupling Biarylation of Nitroaryl Chlorides Through High Speed Ball Milling." International Journal for Innovation Education and Research 3, no. 6 (June 30, 2015): 12–35. http://dx.doi.org/10.31686/ijier.vol3.iss6.376.

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Solvent-free reaction using a high-speed ball milling technique has been applied to the classical Ullmann coupling reaction. Cross-coupling biarylation of several nitroaryl chlorides was achieved in good yields when performed in custom-made copper vials through continuous shaking without additional copper or solvent. Cross-coupling products were obtained almost pure and NMR-ready. These reactions were cleaner than solution phase coupling which require longer reaction time in high boiling solvents, and added catalysts as well as lengthy extraction and purification steps. Gram quantities of cross biaryl compounds have been synthesized with larger copper vials, a proof that this method can be used to reduce industrial waste and for sustainability.

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20

Li, Xiao Chuan, Shan Shan Gong, and Qi Sun. "Synthesis of Phosphonate-Containing 2-Methyl-1,5-Diaminopentane Derivatives." Advanced Materials Research 1046 (October 2014): 104–7. http://dx.doi.org/10.4028/www.scientific.net/amr.1046.104.

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An improved method for the synthesis of α-aminophosphonate based on the Kabachnik-Fields reaction has been developed. The Kabachnik-Fields reactions for the synthesis of the title compounds were investigated in different solvents. The results showed that the solvent-free conditions was optimal for synthesis of this type of compounds.

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21

Raiedhah Alsaiari, Raiedhah Alsaiari, Moustafa A. Rizk Moustafa A Rizk, Esraa Musa Esraa Musa, Huda Alqahtani Huda Alqahtani, Fatima Alqadri Fatima Alqadri, Mervat Mohamed Mervat Mohamed, Mabkhoot Alsaiari Mabkhoot Alsaiari, Ali Alkorbi Ali Alkorbi, Iman Shedaiwa Iman Shedaiwa, and Faeza Alkorbi Faeza Alkorbi. "Supported Ruthenium Catalysts for Oxidation of Benzyl Alcohol under Solvent Free Conditions." Journal of the chemical society of pakistan 44, no. 4 (2022): 322. http://dx.doi.org/10.52568/001069/jcsp/44.04.2022.

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The investigation comprised an evaluation of the use of the catalyst, 1%Ru/TiO2, to oxidize Phenylmethanol into benzenecarbaldehyde. nitrogen adsorption isotherms and transmittance electron microscope (TEM) were deployed to delineate the properties of the supported catalysts. The findings indicated a superior catalytic performance from 1%Ru/TiO2 prepared using sol-immobilization method. No reaction was taken place with blank reaction or with undoped support. This was deemed to be a consequence of the dispersion and loading of Ru on the TiO2.The reaction conditions, i.e., temperature, reaction time, nature of catalyst and activating quantity, were optimized to achieve superior reaction parameters. This process gave rise to a benzyl alcohol transformation rate of up to 10%; and selectivity of benzaldehyde was 98%.

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22

Zare, Abdolkarim, and Manije Dianat. "A highly efficient and green approach for the synthesis of pyrimido[4,5-b]quinolines using N,N-diethyl-N-sulfoethanaminium chloride." Zeitschrift für Naturforschung B 76, no. 2 (January 11, 2021): 85–90. http://dx.doi.org/10.1515/znb-2020-0098.

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Abstract A highly efficient and green protocol for the synthesis of pyrimido[4,5-b]quinolines has been described. The one-pot multicomponent reaction of dimedone with arylaldehydes and 6-amino-1,3-dimethyluracil in the presence of N,N-diethyl-N-sulfoethanaminium chloride ([Et3N–SO3H][Cl]) as an ionic liquid (IL) catalyst under solvent-free conditions afforded the mentioned compounds in high yields and short reaction times. Our protocol is superior to many of the reported protocols in terms of two or more of these factors: the reaction times, yields, conditions (solvent-free versus usage of organic solvents), temperature and catalyst amount.

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23

Moormann, Widukind, Daniel Langbehn, and Rainer Herges. "Solvent-Free Synthesis of Diazocine." Synthesis 49, no. 15 (July 11, 2017): 3471–75. http://dx.doi.org/10.1055/s-0036-1590685.

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A convenient two-step synthesis of diazocine starting from 2-nitrotoluene is described. The first step, the oxidative dimerization of 2-nitrotoluene, is improved to 95% yield. The second step, the reductive azo cyclization, is performed as a solvent-free reaction with lead powder in a ball mill (51% yield). As a reference, the previously described azo cyclization with Zn/Ba(OH)2 is investigated in detail. The results explain why in previous experiments the yields are low and extremely dependent on the reaction conditions. In view of potential applications in photopharmacology, we checked the stability under reducing conditions. Diazocine does not react with glutathione, indicating intracellular stability.

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24

Ye, X. R., C. Daraio, C. Wang, J. B. Talbot, and S. Jin. "Room Temperature Solvent-Free Synthesis of Monodisperse Magnetite Nanocrystals." Journal of Nanoscience and Nanotechnology 6, no. 3 (March 1, 2006): 852–56. http://dx.doi.org/10.1166/jnn.2006.135.

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We have successfully demonstrated a facile, solvent-free synthesis of highly crystalline and monodisperse Fe3O4 nanocrystallites at ambient temperature avoiding any heating. Solid state reaction of inorganic Fe(II) and Fe(III) salts with NaOH was found to produce highly crystalline Fe3O4 nanoparticles. The reaction, if carried out in the presence of surfactant such as oleic acid–oleylamine adduct, generated monodisperse Fe3O4 nanocrystals extractable directly from the reaction mixture. The extracted nanoparticles were capable of forming self-assembled, two-dimensional and uniform periodic array. The new process utilizes inexpensive and nontoxic starting materials, and does not require a use of high boiling point and toxic solvents, thus is amenable to an environmentally desirable, large-scale synthesis of nanocrystals.

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25

Loesch-Zhang, Amelia, Cynthia Cordt, Andreas Geissler, and Markus Biesalski. "A Solvent-Free Approach to Crosslinked Hydrophobic Polymeric Coatings on Paper Using Vegetable Oil." Polymers 14, no. 9 (April 27, 2022): 1773. http://dx.doi.org/10.3390/polym14091773.

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Hydrophobic coatings are of utmost importance for many applications of paper-based materials. However, to date, most coating methods demand vast amounts of chemicals and solvents. Frequently, fossil-based coating materials are being used and multiple derivatization reactions are often required to obtain desired performances. In this work, we present a solvent-free paper-coating process, where olive oil as the main biogenic component is being used to obtain a hydrophobic barrier on paper. UV-induced thiol-ene photocrosslinking of olive oil was pursued in a solvent-free state at a wavelength of 254 nm without addition of photoinitiator. Optimum reaction conditions were determined in advance using oleic acid as a model compound. Paper coatings based on olive oil crosslinked by thiol-ene reaction reach water contact angles of up to 120°. By means of Fourier transform infrared spectroscopy and differential scanning calorimetry, a successful reaction and the formation of a polymer network within the coating can be proven. These results show that click-chemistry strategies can be used to achieve hydrophobic polymeric paper coatings while keeping the amount of non-biobased chemicals and reaction steps at a minimum.

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26

Soleiman-Beigi, Mohammad, Reza Aryan, Maryam Yousofizadeh, and Shima Khosravi. "A Combined Synthetic and DFT Study on the Catalyst-Free and Solvent-Assisted Synthesis of 1,3,4-Oxadiazole-2-thiol Derivatives." Journal of Chemistry 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/476358.

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A novel practical and efficient catalyst-free method for the synthesis of 5-substituted 1,3,4-oxadiazole-2-thiols has been developed, which is assisted by reaction solvent (DMF). The solvent effects on product selectivity were studied based on Onsager’s reaction field theory of electrostatic solvation. The ab initio theoretical studies on the effect of solvents on the process also supported the suitability of DMF as the reaction medium for the preparation of 1,3,4-oxadiazole-2-thiol derivatives.

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27

Bousquet, Till, Mouhamad Jida, Mohamad Soueidan, Rebecca Deprez-Poulain, Francine Agbossou-Niedercorn, and Lydie Pelinski. "Fast and efficient solvent-free Passerini reaction." Tetrahedron Letters 53, no. 3 (January 2012): 306–8. http://dx.doi.org/10.1016/j.tetlet.2011.11.028.

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28

Gladysz, John A. "Reaction: Toward Organic-Solvent-free Synthetic Chemistry." Chem 4, no. 9 (September 2018): 2007–8. http://dx.doi.org/10.1016/j.chempr.2018.08.026.

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29

Nielsen, Simon Feldbæk, Dan Peters, and Oskar Axelsson. "The Suzuki Reaction Under Solvent-Free Conditions." Synthetic Communications 30, no. 19 (October 2000): 3501–9. http://dx.doi.org/10.1080/00397910008087262.

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30

Waddell, Daniel C., and James Mack. "An environmentally benign solvent-free Tishchenko reaction." Green Chem. 11, no. 1 (2009): 79–82. http://dx.doi.org/10.1039/b810714a.

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31

Motiur Rahman, A. F. M., and Adnan A. Kadi. "Solvent free Cannizzaro reaction applying grindstone technique." Arabian Journal of Chemistry 9 (November 2016): S1373—S1377. http://dx.doi.org/10.1016/j.arabjc.2012.02.010.

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32

Miyamoto, Hisakazu, Shotaro Kanetaka, Koichi Tanaka, Kazuhiro Yoshizawa, Shinji Toyota, and Fumio Toda. "ChemInform Abstract: Solvent-Free Robinson Anellation Reaction." ChemInform 31, no. 51 (December 19, 2000): no. http://dx.doi.org/10.1002/chin.200051046.

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33

Ghigo, Giovanni, Matteo Bonomo, Achille Antenucci, Chiara Reviglio, and Stefano Dughera. "Copper-Free Halodediazoniation of Arenediazonium Tetrafluoroborates in Deep Eutectic Solvents-like Mixtures." Molecules 27, no. 6 (March 15, 2022): 1909. http://dx.doi.org/10.3390/molecules27061909.

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Deep Eutectic Solvent (DES)-like mixtures, based on glycerol and different halide organic and inorganic salts, are successfully exploited as new media in copper-free halodediazoniation of arenediazonium salts. The reactions are carried out in absence of metal-based catalysts, at room temperature and in a short time. Pure target products are obtained without the need for chromatographic separation. The solvents are fully characterized, and a computational study is presented aiming to understand the reaction mechanism.

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34

Marchenko, Roman D., and Andrei S. Potapov. "Synthesis of Bis(1,2,3-triazolyl)alkanes in Superbasic and Solvent-Free Conditions." Molbank 2023, no. 1 (January 13, 2023): M1551. http://dx.doi.org/10.3390/m1551.

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Nucleophilic substitution reactions between 1,2,3-triazole and dibromomethane or 1,2-dirbomoethane in a superbasic medium potassium hydroxide–dimethyl sulfoxide gave mixtures of the isomeric bis(1,2,3-triazolyl)alkanes, in which (1,2,3-triazol-1-yl)(1,2,3-triazol-2-yl)alkanes and bis(1,2,3-triazol-2-yl)alkanes were the dominating products, while bis(triazol-1-yl)alkanes were detected only in trace amounts. The same products could also be obtained under solvent-free conditions in a neat reaction mixture. The proposed methods are economically feasible, do not require using toxic solvents or catalysts, and make the (1,2,3-triazol-2-yl)-derivatives, inaccessible by alkyne-azide cycloaddition (click) reactions, readily available.

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35

Mandouma, Ghislain R., Ayunna Epps, and John Barbas. "Synthesis of Substituted 2,2’-Dinitrobiphenyls by a Novel Solvent-Free High Yielding Ullmann Coupling Biarylation:." International Journal for Innovation Education and Research 2, no. 12 (December 31, 2014): 133–49. http://dx.doi.org/10.31686/ijier.vol2.iss12.293.

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Solvent-free reaction using a high-speed ball milling technique has been applied to the classical Ullmann coupling reaction for the first time. Biarylation of 2-iodonitrobenzene was achieved in quantitative yield when performed in a custom-made copper vial through continuous shaking without additional copper or solvent. The product was solid, NMR ready and required no lengthy extraction for purification. This reaction was cleaner, and faster than solution phase coupling which requires longer reaction time in high boiling solvents, added copper catalyst, and lengthy extraction and purification steps. Gram quantities of the biaryl compound were synthesized in larger copper vials. This is a general method that can be used to effectively reduce industrial waste en route to sustainability.

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36

Miao, Changlin, Zhongming Wang, Lingmei Yang, Huiwen Li, Pengmei Lv, Xinshu Zhuang, Zhenhong Yuan, and Wen Luo. "Lipase-Catalyzed Synthesis of Glycerol-Free Biodiesel from Rapeseed Oil and Dimethyl Carbonate." Journal of Biobased Materials and Bioenergy 14, no. 4 (August 1, 2020): 537–43. http://dx.doi.org/10.1166/jbmb.2020.1973.

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The enzymatic production of glycerol-free biodiesel by the transesterification of rapeseed oil was studied using lipase as catalyst. A series of co-solvents were employed in an attempt to improve reaction kinetics. The effects of the reaction conditions (molar ratio of dimethyl carbonate (DMC) and rapeseed oil, type of lipases, amount of lipases, solvent effects, reaction temperature and time) on the conversion and yield of biodiesel and glycerol carbonate (GC) were investigated. The optimal conditions for biodiesel and GC were 20% Novozym 435, 3:1 molar ratio of DMC to rapeseed oil, and with 20% [Omim][BF6] as solvent. Under these conditions, the conversions of 88.51% biodiesel and 73.87% GC have been achieved after 48 h. The biodiesel and GC conversions were eight times higher compared to the conventional solvent-free system, respectively. There was no obvious loss in the biodiesel and GC yield after Novozym 435 having been used for five recycling.

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37

Rubab, Laila, Ayesha Anum, Sami A. Al-Hussain, Ali Irfan, Sajjad Ahmad, Sami Ullah, Aamal A. Al-Mutairi, and Magdi E. A. Zaki. "Green Chemistry in Organic Synthesis: Recent Update on Green Catalytic Approaches in Synthesis of 1,2,4-Thiadiazoles." Catalysts 12, no. 11 (October 29, 2022): 1329. http://dx.doi.org/10.3390/catal12111329.

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Green (sustainable) chemistry provides a framework for chemists, pharmacists, medicinal chemists and chemical engineers to design processes, protocols and synthetic methodologies to make their contribution to the broad spectrum of global sustainability. Green synthetic conditions, especially catalysis, are the pillar of green chemistry. Green chemistry principles help synthetic chemists overcome the problems of conventional synthesis, such as slow reaction rates, unhealthy solvents and catalysts and the long duration of reaction completion time, and envision solutions by developing environmentally benign catalysts, green solvents, use of microwave and ultrasonic radiations, solvent-free, grinding and chemo-mechanical approaches. 1,2,4-thiadiazole is a privileged structural motif that belongs to the class of nitrogen–sulfur-containing heterocycles with diverse medicinal and pharmaceutical applications. This comprehensive review systemizes types of green solvents, green catalysts, ideal green organic synthesis characteristics and the green synthetic approaches, such as microwave irradiation, ultrasound, ionic liquids, solvent-free, metal-free conditions, green solvents and heterogeneous catalysis to construct different 1,2,4-thiadiazoles scaffolds.

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38

Salmar, Siim, Jaak Järv, Tiina Tenno, and Ants Tuulmets. "Role of water in determining organic reactivity in aqueous binary solvents." Open Chemistry 10, no. 5 (October 1, 2012): 1600–1608. http://dx.doi.org/10.2478/s11532-012-0080-8.

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AbstractKinetic data for organic reactions in various binary water-organic solvent mixtures were collected and quantitatively analysed in terms of linear-free-energy relationships by using tert-butyl chloride (2-chloro-2-methylpropane) solvolysis as the reference system. Linear similarity plots for these kinetic data were determined for solvent systems ranging from pure water mixtures up to considerable amount of cosolvent, and 161 similarity coefficients were calculated from slopes of these plots. The existence of these linear plots demonstrated that the solvent effects are of some common nature in all analysed reaction mixtures independent of the reaction type and the cosolvent used. Therefore it was concluded that the observed effects could be connected to the specific solvating properties of water, which govern reactivity even in significant dilution of water by an organic cosolvent. This conclusion was supported by the linear interrelationship between the slopes of similarity plots of different reactions, and hydrophobicity parameters log P of the reacting compounds. The relative solvent effects observed in binary water-organic solvent mixtures were for the first time directly related to the structure of reacting compounds.

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39

Kidwai, Mazaahir, Shweta Rastogi, Ruby Thakur, and Shilpi Saxena. "Solvent-Free Synthesis of 2,4,6-Triaryl Pyridines." Zeitschrift für Naturforschung B 59, no. 5 (May 1, 2004): 606–8. http://dx.doi.org/10.1515/znb-2004-0522.

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A modified method to prepare 1,3,5-triarylpyridines by a [3+2+1] ring annulation reaction is described. Three-component condensation of neat reactants when subjected to microwaves afforded the required product in shorter reaction time with higher yield in comparison to conventional methodologies. The microwave accelerated reaction technique without external solvent renders the whole synthesis into a truly ecofriendly protocol.

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40

Chavelas-Hernández, Leticia, Luis G. Hernández-Vázquez, José D. Bahena-Martínez, Alexa B. Arroyo-Colín, Sinuhe G. Flores-Osorio, Gabriel Navarrete-Vázquez, and Jaime Escalante. "Aza-Michael Additions of Benzylamine to Acrylates Promoted by Microwaves and Conventional Heating Using DBU as Catalyst via Solvent-Free Protocol." Processes 12, no. 1 (December 22, 2023): 34. http://dx.doi.org/10.3390/pr12010034.

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In recent years, the use of solvent-free reactions represents a challenge for organic chemists, since it would help to optimize methodologies and contribute to the development of sustainable chemistry. In this regard, our research group has intensified efforts in the search for reactions that can be carried out in the absence of a solvent. In this paper, we present a protocol for the aza-Michael addition of benzylamine to α,β-unsaturated esters to prepare N-benzylated β-amino esters in the presence of catalytic amounts of DBU (0.2 eq) via solvent-free reaction. Depending on the α,β-unsaturated esters, we observed a reduction in reaction times, with good to excellent yields for aza-Michael addition.

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41

Sapaev, B., F. E. Saitkulov, A. A. Tashniyazov, and OU Normurodov. "Study of methylation reactions of 2-phenylquinazoline-4-tion with “soft” and “hard” methylation agents and determination of its biological activity." E3S Web of Conferences 258 (2021): 04023. http://dx.doi.org/10.1051/e3sconf/202125804023.

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Alkylation reactions of 2-phenylquinazoline-4-thion with methylation agents “soft” (methyl iodide) and “hard” (dimethyl sulfate, methyltozylate) were studied. It was found that the reaction proceeds with the formation of alkyl products at the N3 - and S4 - reaction centers, depending on the methylation agent, solvent and temperature. This indicated the ambivalent nature of the 2-phenylquinazoline-4-tion anion. Prolongation of the reaction time leaded to the formation of a second isomeric product (VII). A slight increase in phenyl N3-product (VII) yield was noted when dimethyl sulfate and methylfolate were used as methylation agents. In non-polar proton-free solvent DMF and dipolar proton-free solvent acetonitrile, only N-methyl product (VII) was formed because of the reaction. An increase in the polarity of the solvent and the “hardness” of the methylation agent leads to an increase in the yield of N3 products.

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42

Olyaei, Abolfazl, Mohsen Vaziri, Reza Razeghi, Shams Bahareh, and Hasan Bagheri. "Novel approach to bis(indolyl)methanes using nickel nanoparticles as a reusable catalyst under solvent-free conditions." Journal of the Serbian Chemical Society 78, no. 4 (2013): 463–68. http://dx.doi.org/10.2298/jsc120506076o.

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A nanosized Nickel as catalyst has been developed for the electrophilic substitution reactions of indole with variousaromatic aldehydes under solvent-free conditions to afford the corresponding bis(indolyl)methanes in high to excellent yields. The described method has promising features such as no hazardous organic solvents or catalysts, short reaction time, high product yields, simple work-up procedure, reusable catalyst and easy product separation without further purification with column chromatography.

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Tahmasbi, Marzieh, Nadiya Koukabi, and Ozra Armandpour. "Sono and nano: A perfect synergy for eco-compatible Biginelli reaction." Heterocyclic Communications 28, no. 1 (January 1, 2022): 1–10. http://dx.doi.org/10.1515/hc-2022-0003.

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Abstract In this study, we evaluated the performance of nano-γ-Fe2O3–SO3H catalyst in the Biginelli reaction and synthesized 3,4-dihydropyrimidine-2-(1H)-ones. This reaction was carried out under solvent-free and ultrasonic irradiation conditions and belonged to one-pot multicomponent reactions (MCRs) with an adopted aromatic aldehyde, ethyl acetoacetate, and urea as starting materials for the beginning of the reaction. The synthesized materials were efficient in synthesizing 3,4-dihydropyrimidine-2-(1H)-ones via the Biginelli reaction under reaction conditions. Thus, the advantages of using nano-γ-Fe2O3–SO3H in the Biginelli reaction are short reaction time, high efficiency, green method, solvent free, and cost-effective. Furthermore, nano-γ-Fe2O3–SO3H as a heterogeneous catalyst can be recycled five times without significantly reducing catalytic activity.

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Cai, Yan Hua. "Studies on Synthesis, Morphology and Theoretical Analysis of Schiff Base Derived From p-Aminobenzoic Acid and p-Hydroxybenzaldehyde by Solvent-Free Reaction Using Jet Milling." Advanced Materials Research 79-82 (August 2009): 1355–58. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1355.

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A novel synthesis method on solvent-free reaction using improved jet milling was described. Synthesis of a schiff base derived from p-hydroxybenzaldehyde and p-aminobenzoic acid had been achieved by solvent-free reaction using improved jet milling, and the structure of the compound have been characterized by Fourier transform infrared spectrometer, 1H nuclear magnetic resonance techniques and mass spectrometry. Differential thermal analysis of reaction process shown that the reaction was complete within 6 min. The scanning electron microscopy shown that the particles of the schiff base were regular and the size of the most particles was 0.5~1 μm. At the same time, the theoretical analysis about reaction process of solvent-free reaction using improved jet milling was preliminary studied. This solvent-free reaction using improved jet milling not only involves mild conditions, a simple operation and short reaction time, but also gives quantitative yield without waste producing work-up procedures. Simultaneously, the investigation also showed this reaction method was feasible, and of benefit to environment.

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Krištofíková, Dominika, Juraj Filo, Mária Mečiarová, and Radovan Šebesta. "Why do thioureas and squaramides slow down the Ireland–Claisen rearrangement?" Beilstein Journal of Organic Chemistry 15 (December 10, 2019): 2948–57. http://dx.doi.org/10.3762/bjoc.15.290.

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A range of chiral hydrogen-bond-donating organocatalysts was tested in the Ireland–Claisen rearrangement of silyl ketene acetals. None of these organocatalysts was able to impart any enantioselectivity on the rearrangements. Furthermore, these organocatalysts slowed down the Ireland–Claisen rearrangement in comparison to an uncatalyzed reaction. The catalyst-free reaction proceeded well in green solvents or without any solvent. DFT calculations showed that the activation barriers are higher for reactions involving hydrogen-donating organocatalysts and kinetic experiments suggest that the catalysts bind stronger to the starting silyl ketene acetals than to transition structures thus leading to inefficient rearrangement reactions.

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46

Ma, Xiaofang, Shunxi Li, Samrat Devaramani, Guohu Zhao, and Daqian Xu. "One-Pot, Regioselective Synthesis of Homopropargyl Alcohols using Propargyl Bromide and Carbonyl Compound by the Mg-mediated Reaction under Solvent-free Conditions." Letters in Organic Chemistry 17, no. 6 (May 20, 2020): 438–42. http://dx.doi.org/10.2174/1570178616666190926104037.

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The elimination of volatile organic solvents in organic synthesis is the most important goal in “Green” chemistry. We report a simple, efficient and facile method for the addition of progargyl bromide to carbonyl compounds using Mg metal as a mediator under solvent-free conditions which could regioselectively generate homopropargyl alcohols efficiently in good to excellent yields. The procedure has advantages such as short reaction time, operationally simple, excellent product yields, high regioselectivity and organic solvent-free.

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Cui, Dong-Xiao, Yue-Dan Li, Jun-Chao Zhu, Yan-Yan Jia, Ai-Dong Wen, and Ping-An Wang. "Highly Efficient Michael Reactions of Nitroolefins by Grinding Means." Current Organic Synthesis 16, no. 3 (June 17, 2019): 449–57. http://dx.doi.org/10.2174/1570179416666190101122150.

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Aim and Objective: The direct β-functionalization of trans-β-nitroolefins by Michael reaction is regarded as an efficient way to provide precursors for β-functional amines. However, Michael additions by grinding means with solvent-free conditons are rarely reported. We have developed facile access to β-functional nitroalkanes by grinding means under solvent-free conditions. Materials and Methods: From commercially available materials including ethyl 2-nitroacetate, alkyl 2-cyanoacetates and malononitrile, the grinding reactions between these above-mentioned activated methylenecompounds and various trans-β-nitroolefins were performed at room temperature and solvent-free conditions. Results: A highly efficient direct Michael reaction of nitroolefins by simple grinding means has been developed. Various trans-nitrostyrenes were easily converted into corresponding β-functional nitroalkanes in excellent yields within 5~10 min (up to 36 examples). Conclusion: Herein, we have developed a simple and efficient way to β-functional nitroalkanes through Michael reactions by grinding means. The grinding Michael reaction is fast, clean and stable and these Michael adducts could be easily converted into the other amino compounds served as building blocks in organic synthesis.

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Chen, Longrui, Betsegaw E. Lemma, Jenna S. Rich, and James Mack. "Freedom: a copper-free, oxidant-free and solvent-free palladium catalysed homocoupling reaction." Green Chem. 16, no. 3 (2014): 1101–3. http://dx.doi.org/10.1039/c3gc41847b.

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Herein, we describe a copper-free, oxidant-free, solvent-free homocoupling reaction using a palladium catalyst under mechanochemical conditions. We extended the methodology to palladium catalyst on solid support which showed a different reactivity and different product ratios from the non-supported catalyst.

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Crole, David A., Simon J. Freakley, Jennifer K. Edwards, and Graham J. Hutchings. "Direct synthesis of hydrogen peroxide in water at ambient temperature." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2190 (June 2016): 20160156. http://dx.doi.org/10.1098/rspa.2016.0156.

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The direct synthesis of hydrogen peroxide (H 2 O 2 ) from hydrogen and oxygen has been studied using an Au–Pd/TiO 2 catalyst. The aim of this study is to understand the balance of synthesis and sequential degradation reactions using an aqueous, stabilizer-free solvent at ambient temperature. The effects of the reaction conditions on the productivity of H 2 O 2 formation and the undesirable hydrogenation and decomposition reactions are investigated. Reaction temperature, solvent composition and reaction time have been studied and indicate that when using water as the solvent the H 2 O 2 decomposition reaction is the predominant degradation pathway, which provides new challenges for catalyst design, which has previously focused on minimizing the subsequent hydrogenation reaction. This is of importance for the application of this catalytic approach for water purification.

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Bora, Pranjal P., H. Atoholi Sema, Barisha Wahlang, and Ghanashyam Bez. "Rapid synthesis of homoallylic alcohol from aldehyde with allyltributylstannane under solvent-free conditions." Canadian Journal of Chemistry 90, no. 2 (February 2012): 167–72. http://dx.doi.org/10.1139/v11-138.

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A catalytic amount (2 mol %) of phosphotungstic acid (PTA) is sufficient to synthesize homoallylic alcohol in excellent yields from aldehyde with allyltributylstannane upon grinding under solvent-free reaction conditions. Easy handling, very short reaction time, solvent-free reaction conditions, and aqueous workup free isolation protocol may make our method very useful for synthetic chemists.

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