Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• . Photocatalytic hydrogen evolution The flow diagram of the setup used for photocatalytic hydrogen evolution is shown in Figure 19. The photocatalyst particles were first put into 414 mL water and dispersed by ultrasonication. The suspension was then filled into the loop photoreactor together with 46 mL methanol

Dissecting Mechanochemistry III

• Lars Borchardt and
• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150

• , Colombia 10.3762/bjoc.18.150 In the past ten years, the use of mechanochemical techniques (e.g., grinding, milling, extrusion, pulsed ultrasonication, resonant acoustic mixing, etc.) have widespread in the field of organic chemistry, enabling the development of new and more sustainable protocols for

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• (mechanochemistry) can be accomplished through various experimental strategies. Among them, ultrasonication of polymeric matrices and ball milling of reaction partners have become the two leading approaches to carry out polymer and small molecule mechanochemistry, respectively. Often, the methodological differences

• molecule mechanochemistry sometimes overlap, evidencing the connection between both approaches. Keywords: ball milling; mechanochemistry; mechanophore; polymer; pulsed ultrasonication; Introduction In the past two decades, the growth in popularity of mechanochemistry has been unmistakable. During this

• (mechanophores) embedded along the polymer chains (Figure 1a) [1][2][3][4]. This is mostly accomplished through pulsed ultrasonication, and to a lesser extent by single-molecule force spectroscopy techniques [5][6]. The second approach habitually makes use of ball milling techniques to bring together small

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• yield, the use of an eco-friendly solvent and a recyclable nanocatalyst, as well as reaction at room temperature. Keywords: 1,4-DHPs; green synthesis; magnetically recyclable catalyst; Ni–chitosan nanoparticles; ultrasonication; Introduction Homogeneous catalysts, despite having an outstanding

• of green chemistry [21]. The application of ultrasound in “traditional” reactions results in a lower reaction time, higher conversion, and simpler methodology and is termed sonochemistry. Ultrasonication is a modern trend in synthetic chemistry that supports the objective of green chemistry, namely

• equimolar mixture of p-toluidine, trans-cinnamaldehyde, and dimethyl but-2-ynedioate, applying both stirring at room temperature and ultrasonication, respectively, in the presence of the synthesized catalyst. For all solvents, the result was much better under sonication compared to stirring at room

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• reacted with different amines 42a–c in the presence of an ethanol–water mixture under ultrasonication, followed by reaction with arylhydrazines, which led to hydrazones 44a–l according to the classical procedure that employs methanol at room temperature. All compounds were evaluated against different

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

• Tobias Klein,
• Franka V. Gruschwitz,
• Maren T. Kuchenbrod,
• Ivo Nischang,
• Stephanie Hoeppener and
• Johannes C. Brendel

Beilstein J. Org. Chem. 2021, 17, 2621–2628, doi:10.3762/bjoc.17.175

• core of the fiber. A slow transition from different organic solvents to water leads first to the formation of µm-long fibers, which can subsequently be fragmented by ultrasonication or dual asymmetric centrifugation. The latter allows for a better adjustment of applied shear stresses, and thus enables

• methods represent an easily implementable technique toward 1D polymer nanostructures with an adjustable length in the range of interest for perspective biomedical applications. Keywords: distribution; dual centrifugation; filomicelles; self-assembly; ultrasonication; Introduction Cylindrical polymer

• interest. While ultrasonication (US) represents a standard but rather harsh fragmentation technique, we additionally introduced dual asymmetric centrifugation (DAC) as an excellent alternative top-down method for effective, more controlled, and adaptable preparation of polymer nanostructures [24][25][26

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• this study, it was noticed that the catalyst could successfully be reused (at least) 7 times in the synthesis of the compounds 3k, 7a, and 11e without a significant loss of the catalytic activity. Effect of ultrasonication on the structure of the catalyst The recovered catalyst after the 7th cycle of

• each synthesis was characterized by XRD to study the structural changes due to ultrasonication. As can be seen in Figure 8, the diffraction peak positions of the catalyst recovered after the synthesis of the compounds 3k, 7a, and 11e (Figure 8b–d), respectively, remained the same as compared to the

• fresh catalyst (Figure 8a). It was also noticed that the broadening in the XRD pattern of the recovered catalyst had increased with an increase of the ultrasonication time. This clearly indicated that the amorphization of the recovered catalyst was enhanced by increasing the ultrasonication time

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• endotermic process is the rate-limiting step and long reaction times are generally associated to this. However, the reaction can be accelerated in conditions that facilitate the dissociation of CO ligands such as heating, microwave irradiation [37][38], visible light, or ultrasonication [39]. Alternatively

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• graphene oxide (rGO) with copper and palladium species (Scheme 15) [77]. In this study, graphite oxide (GO) was generated according to the modified Hummer’s method. Copper(II) was anchored on GO via ultrasonication. In the next step, copper ions were reduced by adding NaBH4. The mixture was then heated at

• at 120 °C for 6 h and then freeze-drying, a 3D graphene hydrogel was produced. After dissolving the 3D graphene 86 in water by ultrasonication, CuNO3⋅3H2O was added into the solution, and this was ultrasonicated for 3 h. ʟ-Ascorbic acid as a reducing agent was added into the solution and stirred for

• in distilled water by ultrasonication. Subsequently, an aqueous solution of CuSO4 was added and stirred for 2 h. The pH value was increased to >10 by adding aqueous NaOH. An aqueous solution of lactulose was added as the reducing agent to the mixture to reduce GO and copper(II). After sonication for

Ultrasonic-assisted unusual four-component synthesis of 7-azolylamino-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines

• Yana I. Sakhno,
• Maryna V. Murlykina,
• Oleksandr I. Zbruyev,
• Anton V. Kozyryev,
• Svetlana V. Shishkina,
• Dmytro Sysoiev,
• Vladimir I. Musatov,
• Sergey M. Desenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2020, 16, 281–289, doi:10.3762/bjoc.16.27

• Republic 10.3762/bjoc.16.27 Abstract Four-component reactions of 3-amino-1,2,4-triazole or 5-amino-1H-pyrazole-4-carbonitrile with aromatic aldehydes and pyruvic acid or its esters under ultrasonication were studied. Unusual for such a reaction type, a cascade of elementary stages led to the formation of

• 7-azolylaminotetrahydroazolo[1,5-a]pyrimidines. Keywords: 5-amino-1H-pyrazole-4-carbonitrile; 3-amino-1,2,4-triazole; 7-azolylaminotetrahydroazolo[1,5-a]pyrimidines; heterocycle; multicomponent reaction; ultrasonication; Introduction Tetrahydropyrimidines are heterocycles of high pharmacological

• such interactions can be tuned, for example, by application of a condition-based divergence strategy [25], which is based on the variation of solvents, catalysts, and activation methods [16][26][27][28][29]. Thus, using nonclassical activation methods such as ultrasonication and microwave irradiation

Isolation of fungi using the diffusion chamber device FIND technology

• Benjamin Libor,
• Henrik Harms,
• Stefan Kehraus,
• Ekaterina Egereva,
• Max Crüsemann and
• Gabriele M. König

Beilstein J. Org. Chem. 2019, 15, 2191–2203, doi:10.3762/bjoc.15.216

• detected using FlexStation 3 (Molecular Devices). FIND procedure For experiment 1, 5 mL of soil (Falcon tube) was diluted in 45 mL of sterile-filtered NaCl 0.85% solution (Ringer solution). This solution underwent manual agitation for 10 minutes and ultrasonication using a Bandelin Sonorex at 100

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• % yield in the final step (Supporting Information File 1, Scheme S1). Preparation and properties of the nanoreactor To prepare nanoranged particles of BATA-MC the synthesized macrocycle was suspended in water followed by ultrasonication for five minutes. Then, the dispersion of BATA-MC in water was

• applications in future. Experimental General procedure for the synthesis of pyrrolo[2,3,4-kl]acridinone derivatives First 53.1 mg (10 mol %) of BATA-MC was dissolved in 3 mL of H2O by ultrasonication for five minutes. Then, 5,5-dimethylcyclohexane-1,3-dione (140 mg, 1 mmol), aromatic or aliphatic amine (1 mmol

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• previously proposed by Marcaccini and co-workers [17]. Here, the route included the Ugi-4CR reaction of varied amines and isocyanides with the androstanic aldehyde 4 and chloroacetic acid followed by a post-cyclization reaction by treating the Ugi products 5 with ethanolic KOH under ultrasonication. This

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

• water slowly into MeCN solution under ultrasonication yielding a mixture solvent of H2O/MeCN = 10:1 (v/v), 1 assembled into a well-defined nanobelt in extremely polar aqueous environment, which further entangled into networks (Figure 2c) [68]. Previously, Würthner’s group reported the self-assembly of a

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• are time-consuming and energy intensive, as well. Zou et al. reported an effective strategy for acid-free sulfonation of MWCNTs using the combination of ultrasonication and heating of the mixture of MWCNTs-COOH and (NH4)2SO4 solution. After washing the mixture with distilled water, the final product

Bi-mediated allylation of aldehydes in [bmim][Br]: a mechanistic investigation

• Mrunesh Koli,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2018, 14, 2198–2203, doi:10.3762/bjoc.14.193

• activators (chemical additives and ultrasonication) for the Bi-mediated allylation of benzaldehyde (1a), as the model substrate with commercially available and inexpensive allyl bromide (Scheme 1) at room temperature (25 °C) [39][40][41][42]. The results are shown in Table 1. As reported earlier [30], the

• furnished 2a in lesser yields (Table 1, entries 3–8) even under metal activation by KF (Table 1, entries 5 and 8) or ultrasonication (Table 1, entries 4 and 7). Reduction in the amounts of Bi and allyl bromide under these conditions led to significantly poorer results (data not shown). The use of the mixed

• solvent THF/H2O (1:1, v/v) at room temperature or under sonication increased the reaction time (14 h), but furnished 2a in similar yields (60–65%) as obtained in DMF or MeCN-KF (Table 1, entries 9 and 10 vis-à-vis 2 and 4). In water, the reaction yield was modest (entry 11). Ultrasonication in water gave

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• microwave heating [7][8][9][10][11][12][13][14][15], ultrasonication [16][17][18], ligand-free methodologies [19][20][21][22][23][24][25] and the use of water-soluble palladium pre-catalysts/catalysts [26][27][28][29][30]. The latter is the preferred choice since it allows for the reusability of the

Novel approach to hydroxy-group-containing porous organic polymers from bisphenol A

• Tao Wang,
• Yan-Chao Zhao,
• Li-Min Zhang,
• Yi Cui,
• Chang-Shan Zhang and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 2131–2137, doi:10.3762/bjoc.13.211

• acid (0.5 g) was suspended in o-dichlorobenzene (8.0 mL) in a glass tube. After ultrasonication for 0.5 h, the mixture was degassed by at least three freeze–pump–thaw cycles. The tube was frozen at 77 K (liquid nitrogen bath) and evacuated to high vacuum and flame-sealed. After 180 °C for 72 h, the

Solvent-free sonochemistry: Sonochemical organic synthesis in the absence of a liquid medium

• Deborah E. Crawford

Beilstein J. Org. Chem. 2017, 13, 1850–1856, doi:10.3762/bjoc.13.179

• experiments (Scheme 1), both reagents were used as received, o-vanillin came in the form of small flakes and 1,2-phenylenediamine was received as large crystalline beads (Figure 2). Upon sonication of the mixed reagents (using a standard ultrasonication bath with a frequency of 35 kHz) for 60 minutes, it was

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• heating, ultrasonication and solvent-free conditions alleviated the drawbacks to a major extent [56][57][58][59][60][61]. One such useful strategy include manganese dioxide (MnO2)-mediated oxidative aromatization of 1,4-DHP 45 to afford substituted pyridine derivatives 46 under microwave conditions

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• . In 2015, Yunus et al. synthesized CDs by the ultrasonication of glucose or sucrose in the presence of oxidising conditions afforded by H3PO4/H2SO4 (Scheme 6) [36]. The resultant CDs were blue emissive and the use of strong oxidising conditions during their synthesis afforded CDs with surface

3,6-Carbazole vs 2,7-carbazole: A comparative study of hole-transporting polymeric materials for inorganic–organic hybrid perovskite solar cells

• Wei Li,
• Munechika Otsuka,
• Takehito Kato,
• Yang Wang,
• Takehiko Mori and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2016, 12, 1401–1409, doi:10.3762/bjoc.12.134

• oxide (FTO)-coated glass substrates (20 Ω per square) were patterned to fabricate the solar cells. These substrates were successively washed by ultrasonication in water, acetone, and isopropyl alcohol for 10 min each, and then dried in a stream of dry air. The washed substrates were further treated with

Preparation of Pickering emulsions through interfacial adsorption by soft cyclodextrin nanogels

• Shintaro Kawano,
• Toshiyuki Kida,
• Mitsuru Akashi,
• Hirofumi Sato,
• Motohiro Shizuma and
• Daisuke Ono

Beilstein J. Org. Chem. 2015, 11, 2355–2364, doi:10.3762/bjoc.11.257

• ultrasonication. Previously, we prepared a urethane-crosslinked DM-β-CD/PDI polymer at a higher crosslinker/DM-β-CD feed ratio (>5.0). The resulting polymer forms a submicrometer-sized particle and does not disperse in water [18]. These results reveal that controlling the crosslinking degree gives a polymer with

• water was changed twice daily. Then the aqueous dispersion was lyophilized for three days to yield a white powder as a urethane-crosslinked DM-β-CD polymer. The CD nanogel was prepared by the redispersion of the powder in distilled water with the aid of ultrasonication and stored in a refrigerator until

The unexpected influence of aryl substituents in N-aryl-3-oxobutanamides on the behavior of their multicomponent reactions with 5-amino-3-methylisoxazole and salicylaldehyde

• Volodymyr V. Tkachenko,
• Elena A. Muravyova,
• Sergey M. Desenko,
• Oleg V. Shishkin,
• Svetlana V. Shishkina,
• Dmytro O. Sysoiev,
• Thomas J. J. Müller and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2014, 10, 3019–3030, doi:10.3762/bjoc.10.320

• -oxobutanamides on the behavior of the reaction was discovered. The key influence of ultrasonication and Lewis acid catalysts led to an established protocol to selectively obtain two or three types of heterocyclic scaffolds depending on the substituent in the N-aryl moiety. Keywords: 5-amino-3-methylisoxazole

• ; catalysis; chemoselectivity; heterocycle; multicomponent reaction; ultrasonication; salicylaldehyde; Introduction Generally, considerable interest in heterocyclic compounds is due to their key role in biological processes in nature and biological activity. In particular, condensed heterocycles bearing a

• azoloazine with high chemo- and regioselectivity [11][13][14][15]. In particular, three-component heterocyclizations involving 3-amino-1,2,4-triazoles or 4-substituted 5-aminopyrazoles yielded either 4,5,6,7-tetrahydroazolo[1,5-a]pyrimidine-6-carboxamides under ultrasonication at room temperature (kinetic

Features of the behavior of 4-amino-5-carboxamido-1,2,3-triazole in multicomponent heterocyclizations with carbonyl compounds

• Eugene S. Gladkov,
• Katerina A. Gura,
• Svetlana M. Sirko,
• Sergey M. Desenko,
• Ulrich Groth and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2012, 8, 2100–2105, doi:10.3762/bjoc.8.236

• similar MCRs of numerous other aminoazoles, a change of direction of the heterocyclizations in the case of 4-amino-5-carboxamido-1,2,3-triazole was not observed when microwave or thermal heating was substituted by ultrasonication at ambient temperature. Keywords: 4-amino-5-carboxamido-1,2,3-triazole

• chromatographically detected in either of the procedures applied. It is worth noting that in our previous works [9][10][11][12][13][14][15][16][17] we also showed a possibility to change the direction of similar MCRs by replacement of conventional thermal or MW heating with room temperature ultrasonication. However

• , treatment of the starting compounds 1 and 2a,b under ultrasonication at ambient temperature in acetic acid, which was selected instead of methanol due to solubility problems, also yielded only heterocycles 4a,b (Method C). The yields and purity of the compounds obtained under ultrasonication were slightly