Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• of polar and ionic species and attempts to enhance scCO2 viscosity. Keywords: CO2 chemistry; microemulsion; self-assembly; supercritical CO2; surfactant; viscosity; Introduction In this day and age, sustainability and renewability are watchwords. This includes focus within the scientific community

• additives. Focus has primarily been in surfactant and polymer design in water-in-CO2 (w/c) systems, however, attention is now beginning to expand into other alternative systems, including ionic liquid-in-CO2 systems [54][55][56] and the production of microstructures such as lamellar and bicontinuous phases

• [43][48]. Solubility Surfactants Surfactant tails – fluorinated surfactants: Fluorine has a high electron affinity and electronegativity, hence fluorocarbons with a carbon number (n) that is equal to or greater than 4 have lower boiling points and refractive indices than the corresponding hydrocarbons

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

• Sudipta Pathak,
• Kamalesh Debnath and
• Animesh Pramanik

Beilstein J. Org. Chem. 2013, 9, 2344–2353, doi:10.3762/bjoc.9.269

• , both for aromatic and aliphatic amines. We restrained the reaction to using PEG–OSO3H as a Brønsted acid–surfactant combined catalyst in aqeous solution under refluxing conditions as well as under solvent-free conditions (Table 1, entries 7 and 8). Although under solvent-free conditions the required

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Influence of cyclodextrin on the solubility and the polymerization of (meth)acrylated Triton^® X-100

• Melanie Kemnitz and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2176–2183, doi:10.3762/bjoc.8.245

• ®; randomly methylated β-cyclodextrin (RAMEB-CD); rheology; Triton® X-100 (poly(ethylene glycol)tert-octylphenyl ether); Introduction Triton® X-100 (1) is a macromolecular, nonionic surfactant with an average number of ethylene oxide units of 9.5. The tert-octylphenyl group is a hydrophobic moiety whereas

• equiv of RAMEB-CD to 1 exhibited a hydrodynamic diameter of 1.4 nm and the diameter of the 1:2 complex was determined to 2.1 nm. The different hydrodynamic diameters of the complexes indicate that different complexes are formed. Triton® X-100 (1) as a macromolecular surfactant becomes insoluble above 66

Continuous preparation of carbon-nanotube-supported platinum catalysts in a flow reactor directly heated by electric current

• Alicja Schlange,
• Antonio Rodolfo dos Santos,
• Ulrich Kunz and
• Thomas Turek

Beilstein J. Org. Chem. 2011, 7, 1412–1420, doi:10.3762/bjoc.7.165

• salt on carbon support material followed by the reduction with a proper reducing agent (NaBH4, N2H4) or under a gaseous reducing environment (H2), microemulsion method, based on a water–oil system where surfactant molecules are used for stabilization of nanoparticles, and colloidal method, based on

Protonation and deprotonation induced organo/hydrogelation: Bile acid derived gelators containing a basic side chain

• Uday Maitra and
• Arkajyoti Chakrabarty

Beilstein J. Org. Chem. 2011, 7, 304–309, doi:10.3762/bjoc.7.40

• be primarily responsible for their aggregation in water. Unlike conventional surfactant molecules, bile acid salts possess a rigid steroidal backbone, with polar hydroxyl groups on the concave α-face and methyl groups on the convex β-face. On the other hand, relatively few bile acid derived

Olefin metathesis in nano-sized systems

• Didier Astruc,
• Abdou K. Diallo,
• Sylvain Gatard,
• Liyuan Liang,
• Cátia Ornelas,
• Victor Martinez,
• Denise Méry and
• Jaime Ruiz

Beilstein J. Org. Chem. 2011, 7, 94–103, doi:10.3762/bjoc.7.13

• reactions can proceed in the presence of water even without surfactant, but the amount of 1st- or 2nd-generation Grubbs catalyst required then reaches 4 to 5% for good to high-yield reactions [66][67], which is of the order of 100 times more ruthenium catalyst than under our reaction conditions [63]. We

Surfactant catalyzed convenient and greener synthesis of tetrahydrobenzo[a]xanthene-11-ones at ambient temperature

• Pravin V. Shinde,
• Amol H. Kategaonkar,
• Bapurao B. Shingate and
• Murlidhar S. Shingare

Beilstein J. Org. Chem. 2011, 7, 53–58, doi:10.3762/bjoc.7.9

• ]xanthen-11-one using tetradecyltrimethylammonium bromide (TTAB) at room temperature in water is described. Keywords: green chemistry; in-water synthesis; surfactant; tetradecyltrimethylammonium bromide (TTAB); xanthene; Introduction The development of novel synthetic methodologies to facilitate the

• cetyltrimethylammonium bromide (CTAB), methyltriphenylphosphonium bromide (MTPPB) and cetylpyridinium chloride (CPC) as well as an anionic surfactant, sodium dodecyl sulfate (SDS), were utilized at ambient temperature. From these preliminary studies, it was observed that the anionic surfactant SDS and cationic

• surfactants CPC and MTPPB gave the desired product albeit in low yields, i.e., 57%, 32% and 59% respectively (Table 1, entries 1–3). In contrast, the cationic surfactant CTAB accelerated the model reaction to afford the desired product in good 81% yield (Table 1, entry 4). From this, it was concluded that

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• ; polymer colloids; polymerization; Review Introduction Miniemulsions are a special class of emulsions that are stabilized against coalescence (by a surfactant) and Ostwald ripening (by an osmotic pressure agent). The miniemulsions are produced by high-energy homogenization and usually yield stable and

• ), degenerative iodine transfer [48], and nitroxide mediated polymerization (NMP). ATRP in miniemulsions was recently described in several reviews [52][53]. The kinetics of RAFT polymerization in miniemulsion has been discussed by Tobita [54] and thus no detailed description is required here. Surfactant monomer

• (surfmer) in radical miniemulsion polymerization The presence of the surfactant used to stabilize the latexes can have an unfavorable effect on surface properties of films prepared from these latexes. Therefore the use of copolymerizable surfactants was investigated for a number of different polymerization

Cross-metathesis of allylcarboranes with O-allylcyclodextrins

• Ivan Šnajdr,
• Zbyněk Janoušek,
• Jindřich Jindřich and
• Martin Kotora

Beilstein J. Org. Chem. 2010, 6, 1099–1105, doi:10.3762/bjoc.6.126

• , presumably because of their insolubility in the aforementioned solvents. To overcome the problem of the solubility of free O-allylcyclodextrins, the reaction was carried out in water in the presence of surfactant (SDS – sodium dodecyl sulfate), however, cross-metathesis did not occur. Conclusion The results

Differences between β-Ala and Gly-Gly in the design of amino acids-based hydrogels

• Andreea Pasc,
• Firmin Obounou Akong,
• Sedat Cosgun and
• Christine Gérardin

Beilstein J. Org. Chem. 2010, 6, 973–977, doi:10.3762/bjoc.6.109

• networks as a result of intimate interactions between gelator molecules. Keywords: amino acid; histidine; hydrogel; peptide-based surfactant; soft matter; supramolecular; Introduction Hydrogels continue to attract much interest due to their versatile applications in tissue engineering, biosensing, drug

• building blocks for supramolecular architectures such as gels [8][9]. The structure of the surfactant is a major factor for their gelator properties. As reported in the literature [1], unless the molecules remain in solution, when a hot, homogeneous solution of the gelator, is cooled, the molecules start

• surfactant molecule, 2 × 3.4 nm (calculated using MOPAC method, CS Chem Office). Upon heating, the intensity of the peak decreased drastically which can be attributed to a phase transition between 50 and 60 °C. The phase transition temperature was in agreement with the one observed by the dropping ball

Pyridinium based amphiphilic hydrogelators as potential antibacterial agents

• Sayanti Brahmachari,
• Sisir Debnath,
• Sounak Dutta and
• Prasanta Kumar Das

Beilstein J. Org. Chem. 2010, 6, 859–868, doi:10.3762/bjoc.6.101

• sharp diffraction peak was obtained in the small angle region at 2θ = 2.37° which corresponds to a d-spacing of 3.71 nm indicating an ordered arrangement of the molecules in the gel state (Figure 7). The observed d-spacing was greater than the length of a single surfactant molecule, 2.6 nm (calculated

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• a strong fluorescence with maxima at 520 nm and a large Stokes-shift of 50 nm. However, due to the aliphatic structure of the main chain, the thermal stability was rather poor. Photoluminescent polyelectrolyte-surfactant complexes were obtained from an amphiphilic, unsymmetrically substituted DPP

Chromo- and fluorophoric water-soluble polymers and silica particles by nucleophilic substitution reaction of poly(vinyl amine)

• Katja Hofmann,
• Ingolf Kahle,
• Frank Simon and
• Stefan Spange

Beilstein J. Org. Chem. 2010, 6, No. 79, doi:10.3762/bjoc.6.79

• ]. Modified PVAm is expected to be useful in the preparation of polymeric water-soluble dyes [13], in mimicking natural enzymes [14] and as a polymeric surfactant [15]. Depending on the pH of the aqueous solution, the primary amino groups of PVAm can be partly protonated (−NH3+) or they can be present as

New amphiphilic glycopolymers by click functionalization of random copolymers – application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin

• Otman Otman,
• Paul Boullanger,
• Eric Drockenmuller and
• Thierry Hamaide

Beilstein J. Org. Chem. 2010, 6, No. 58, doi:10.3762/bjoc.6.58

• concentration of free surfactant in the aqueous phase. The hydrophilic part is most often constructed from PEG chains. In addition to the steric stabilization, this PEG coating reduces the detection of particles or liposomes by the immune system and consequently, the reticular endothelial uptake of

• stabilization of polymers in dispersed media. This behavior was observed when using other types of glycopolymers [6][12] where a second polymer surfactant was required to assure a stable colloidal stabilization upon long time storage. This was tentatively interpreted in terms of layer thickness of the polymer

• surfactant adsorbed onto the particles. We used here Pluronics instead of poly(vinyl alcohol) (PVA), as proposed by Quintanar and Fessi, to get a higher solid content for the nanoparticles suspensions (the evaporation step rapidly leads to highly viscous suspensions because of the high molecular weight of

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• subsequently developed utilizing nanostructured MoO3 (Scheme 11B) [47][48]. Recently, Kobayashi et al. reported a dehydrative nucleophilic substitution of benzyl alcohols in water employing a dodecylbenzenesulfonic acid (DBSA) as a surfactant-type Brønsted acid catalyst. With this green methodology a variety

N-acylation of ethanolamine using lipase: a chemoselective catalyst

• Mazaahir Kidwai,
• Roona Poddar and
• Poonam Mothsra

Beilstein J. Org. Chem. 2009, 5, No. 10, doi:10.3762/bjoc.5.10

• for hazard assessment of a surfactant because degradation often reduces the toxicity of these chemicals [19]. The hydroxy-substituted aliphatic amides 3a–d act as surfactants, synthesized from fatty acids or esters 1a–h and ethanolamine (2) and they are highly acceptable to the environment as they are