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[Display omitted] Biphasic solvents can decrease the regeneration energy of CO 2 capture. As an intramolecular hybrid diamine, 3-Dimethylaminopropylamine (DMAPA) had a primary amino group and a tertiary amino group, which could absorb CO 2 by combining zwitterion and base-catalyzed hydration mechanism. The derived DMAPA/ n -PeOH/H 2 O biphasic absorbent possessed high CO 2 absorption capacity (1.46 mol/mol) and large CO 2 -rich phase loading (6.27 mol/L), which were superior to existing mixed amine systems. At 393.15 K, this system had a large desorption amount of 4.91 mol/L and a fast desorption rate (6.68 E-3 mol/L·s), which were 2.84 and 3.73 times of 30 wt% MEA. The associated total regeneration energy was reduced to 1.36 GJ/t CO 2 , only 34.1 % of MEA absorbent. The reaction mechanism and origin of phase separation were revealed by NMR analysis and quantum chemistry calculations. In addition, low viscosity and corrosiveness were revealed and conducive for industrial application. [ABSTRACT FROM AUTHOR]

Hypothesis: Worm-like micelles triggered by carbon dioxide (CO2), as an abundant, inert, and green stimulus have recently attracted much interest. These materials have many potential applications, including heat transfer, rheological control, personal protection and enhanced oil recovery (EOR). An ideal CO2-responsive worm-like micelle reveals a reversible transition state (from sol to gel state and vice versa) in response to environmental changes. The most important feature of these systems during these transitions is that CO2 does not accumulate in the system upon repeated cycles. Herein, we prepared two types of materials based on 3-(dimethylamino)-1-propylamine sodium dodecyl sulfate (DMAPA-SDS) as a small molecule, and poly(2-(dimethylamino)ethyl methacrylate-b-polymethyl mthacrylate)-SDS [(PDMAEMA-b-PMMA)-SDS] as a macromolecule to examine possible formation of CO2-responsive worm-like micelles. Methods: Amine groups in the structure of DMAPA and PDMAEMA-b-PMMA can be protonated and ionized to quaternary ammonium salts by CO2 bubbling and interact with SDS to possibly form a worm-like micelle through non-covalent electrostatic attraction. The viscosity and structural features of aqueous solutions were evaluated before and after being exposed to CO2 by rheometry and 1H NMR, respectively. The rheometry results showed shear thinning and gel-like behaviors at high shear rates and frequencies, respectively. Findings: The results showed that for a DMAPA-SDS small molecule an ideal reversible CO2-responsive worm-like micelle was formed and a sol-to-gel transition was observed, whereas in using a macromolecule an irreversible agglomeration occurred. The absence of reversible sol-gel transitions and the presence of heavy agglomeration for the (PDMAEMA-b-PMMA)-SDS macromolecule was attributed to entanglements of its long polymer chains. Therefore, DMAPA-SDS as small molecule with its ideal CO2-responsive worm-like micelle has potential in different useful applications, particularly in EOR.

[Display omitted] • Surface active amine was tested for CO 2 capture and bicarbonate generation. • Surface active amine was DMAPA with built-in surface activity. • PO groups were incorporated into DMAPA as built-in surface activity. • The built-in surface activity with 6 PO groups enhanced CO 2 solubilization by 16%. • DMAPA-6PO enhanced bicarbonate generation by 54% in comparison to DMAPA. We present for the first time the CO 2 capture and in-situ conversion into bicarbonate as a carbon-bearing product using an amine with built-in surface activity. The surface-active amine was 3-(dimethylamino)propylamine (DMAPA) modified with propylene oxide (PO) groups (DMAPA-xPO, x = 4, 6, 8, 12). Analysis of the CO 2 capture capacity data with 13C Nuclear Magnetic Resonance (NMR) spectroscopy determined the bicarbonate concentrations and the generation mechanism during the CO 2 capture influenced by the PO groups, establishing a relationship between CO 2 solubility, pH of the solution, and steric effect. Results demonstrated the effectiveness of the built-in surface activity with an optimal PO level (DMAPA-6PO). DMAPA-6PO enhanced the bicarbonate generation by 54%, in comparison to DMAPA, under ambient conditions. [ABSTRACT FROM AUTHOR]

Abstract Ionic liquids (ILs) have been widely investigated as the promising green absorbents for CO 2 capture. In this work, four low-viscous diamino protic ionic liquids (PILs), including N , N -dimethyl-1,3-propane diamine 2-fluorophenolate ([DMAPAH][2F-PhO]), N , N -dimethyl-1,3-propane diamine 3-fluorophenolate ([DMAPAH][3F-PhO]), N , N -dimethyl-1,3-propane diamine 3-fluorophenolate ([DMAPAH][4F-PhO]), and N , N -dimethyl-1,3-propane diamine 3,5-difluorophenolate ([DMAPAH][3,5F-PhO]), were prepared and evaluated for CO 2 capture. The solubilities of CO 2 in these PILs were measured using an isochoric saturation technique at temperatures from 303.2 to 333.2 K and pressure up to 1.5 bar. It was found that the PILs are excellent absorbent for CO 2 capture with the best absorptive capacity of 3.99 mol CO 2 /kg IL (0.86 mol CO 2 /mol IL), which is superior or competitive to most reported ILs. Furthermore, the captured CO 2 was easy to release by heating and decompression, leading regeneration of the PILs. In addition, a plausible mechanism of CO 2 absorption in these PILs was proposed via a combination of chemical and physical absorption by NMR, FTIR, and mass spectrum (MS). Highlights • Low-viscous diamino PILs with fluorine-substituted phenolic anions for improving CO 2 reversible capture • Solubilities of CO 2 in PILs were measured at temperatures from 303.2 to 333.2 K and pressure up to 1.5 bar. • Spectral properties were studied to insight into the absorption mechanism of CO 2 in PILs. • [DMAPAH][4F-PhO] shows an extremely high capacity of 3.99 mol CO 2 /kg IL. • The mechanism was proposed via the formation of carbamate occurring at the anion. [ABSTRACT FROM AUTHOR]

In this work, the stopped-flow technique is used to determine the kinetics data in terms of pseudo first-order rate constants ( k 0 ) for the homogenous reaction of CO 2 into aqueous solutions of 3-dimethylaminopropylamine (DMAPA) and 3-diethylaminopropylamine (DEAPA) as amine concentrations ranged from 0.05 kmol/m 3 to 0.15 kmol/m 3 and temperature ranged from 293 K to 313 K. It is found that k 0 increased with increasing temperature and with increasing amine concentration. The mechanism of the pseudo first-order chemical reaction hypothesis is applied to interpret the experimental data. The Arrhenius expressions as k 2 = 8.69 × 10 9 × exp ( − 4226.2 / T ) for DMAPA and k 2 = 7.21 × 10 12 × exp ( − 6162.9 / T ) for DEAPA are obtained. The results show that the experimental CO 2 absorption rates exhibited good agreement with predicted CO 2 absorption rates with an average relative deviation (ARD) of 2.34% and 7.53%, respectively. Finally, the interaction of tertiary amine groups with primary amine groups and the effect of molecular structure on the interaction are discussed by comparing the CO 2 absorption and desorption performances in five different systems (MEA, DEEA, MEA + DEEA, DMAPA, DEAPA). It is found that the intermolecular interaction of amino groups is stronger than that of intramolecular interaction. [ABSTRACT FROM AUTHOR]

Background: The prevalence of sensitization to cocamidopropyl betaine (CAPB) in China has not been reported. Objective: This study is to evaluate the prevalence of CAPB sensitization in patients patch tested in Peking University Third Hospital, Beijing. Methods: 429 consecutive patients with suspected allergic contact dermatitis were patch tested with CAPB 1.0% aqueous, 3-dimethylaminopropylamine (DMAPA) 1.0% aqueous as well as a modified European standard series of allergens from June 2005 to August 2006. Results: 42 patients (9.8%) had a positive reaction to CAPB. 25 of them (59.5%) were considered relevant. Of those, 7 were head and/or neck dermatitis, 4 hand dermatitis, 1 cheilitis, and the other 13 patients were widespread dermatitis. 10 out of 429 (2.3%) patients reacted to DMAPA. Of those, 8 were relevant and 6 of them also reacted to CAPB. Conclusion: The rate of CAPB sensitization in our study is higher than previously reported elsewhere. CAPB is a common cosmetic allergen in Beijing. Both CAPB and DMAPA should be tested in patients with suspected cosmetic dermatitis. [ABSTRACT FROM AUTHOR]

Cocamidopropyl betaine (CAPB) is an amphoteric surfactant commonly used in personal care products and surface cleaners. Patch testing with commercially-available CAPB has yielded occasional reactions indicative of allergic contact dermatitis. To determine if subjects with previous positive patch tests would react in provocative use tests of products containing CAPB, and to study various contaminants in commercial CAPB supplies for allergenicity in these subjects. 10 subjects previously positive to CAPB on patch testing used a hair shampoo, hand soap, and both wash containing CAPB for 1 6 weeks or until a reaction developed. Later, they were patch tested to 2 different purity grades of CAPB and 3 possible manufacturing contaminants (dimethylaminopro-pylamine, amidoamine, and sodium monochloroacetate). 7 of the 10 subjects developed dermatitis from 1 or more CAPB-containing products at some point during the studs. 9 of the 10 use-test subjects were then patch tested, and 6 of these subjects showed a reaction to amidoamine (0.% aq.). None reacted to dimethylaminopropylamine (0.1% pet.). 1 subject reacted to (CAPB) but not to amidoamine. In the follow-up patch testing with CAPB that was free of amidoarmine, there were no positive reactions. Most subjects who were patch-test-positive showed a reaction when using CAPB-containing skin and hair care products. The chemical amidoantine, which is used in the synthesis of CAPB and which is a known contaminant of CAPB preparations, is likely to be the actual sensitizer in most cases rather than CAPB itself. The results do not rule out the possibility CAPB itself may be an allergen in rare cases. [ABSTRACT FROM AUTHOR]

Streptogramins are potent drugs against numerous highly resistant pathogens and therefore are used as antibiotics of last-resort human therapy. They consist of a mixture of two different types of chemical substances - the group A streptogramins, which are polyunsaturated macrolactones, and the group B streptogramins, representing cyclic hexadepsipeptides. Streptogramins are unique in their mode of action: each component alone exhibits a moderate bacteriostatic activity by binding to the bacterial 50S ribosomal subunit and thereby blocking translation, whereas the synergic combination of both substances is up to hundred fold more effective than the single compounds, resulting in a bactericidal activity. The streptogramin biosynthetic genes are organized as large antibiotic superclusters. These clusters harbour numerous regulatory genes, which encode different types of regulators that together form a complex hierarchical signalling system, which governs the regulation of streptogramin biosynthesis. Resistance is also regulated by this cascade. However, whereas resistance against streptogramins is quite well understood in diverse pathogenic organisms, only little is known about how the natural producer strains protect themselves against these toxic compounds. Here, we give an overview about the recent advances in streptogramin investigations with a main focus on the best-studied representatives, pristinamycin and virginiamycin. We concentrate on the biosynthesis of these compounds, their regulation and resistance determinants as well as their application in medicine and food industry., (Copyright © 2013 Elsevier GmbH. All rights reserved.)