Surfactants

Kosswig, K.

doi:10.1002/14356007.a25_747

Cited by 55 publications

(41 citation statements)

References 95 publications

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“…To disrupt the surfactancy of longer alkyl-chain analogues, oxygen atoms are placed within the alkyl chains. The strategy is analogous to replacing the sodium dodecyl sulfate (lauryl sulfate) in soaps and shampoos with ether-modified, less skin-irritating analogue, sodium laureth sulfate [87,88]. A first hint that oxygen insertion greatly diminishes the toxicity was reported in 2004 [54].…”

Section: Design Of Mn Porphyrins-based Efficacious and Bioavailable Smentioning

confidence: 99%

Diverse functions of cationic Mn(III) N-substituted pyridylporphyrins, recognized as SOD mimics

Batinić‐Haberle

Rajić

Tovmasyan

et al. 2011

Free Radical Biology and Medicine

128

201

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Oxidative stress, a redox imbalance between the endogenous reactive species and antioxidant systems, is common to numerous pathological conditions such as cancer, central nervous system injuries, radiation injury, diabetes etc. Therefore, compounds able to reduce oxidative stress have been actively sought for over 3 decades. Superoxide is the major species involved in oxidative stress either in its own right or through its progeny, such as ONOO−, H2O2, ·OH, CO3·−, and ·NO2. Therefore, the very first compounds developed in the late 1970-ies were the superoxide dismutase (SOD) mimics. Thus far the most potent mimics have been the cationic meso Mn(III) N-substituted pyridylporphyrins and N,N′-disubstituted imidazolylporphyrins (MnPs), some of them with kcat(O2·−) similar to the kcat of SOD enzymes. Most frequently studied are ortho isomers MnTE-2-PyP5+, MnTnHex-2-PyP5+, and MnTDE-2-ImP5+. The ability to disproportionate O2·− parallels their ability to remove the other major oxidizing species, peroxynitrite, ONOO−. The same structural feature that gives rise to the high kcat (O2·−) and kred (ONOO−), allows MnPs to strongly impact the activation of the redox-sensitive transcription factors, HIF-1α, NF-κB, AP-1, and SP-1, and therefore modify the excessive inflammatory and immune responses. Coupling with cellular reductants and other redox-active endogenous proteins seems to be involved in the actions of Mn porphyrins. While hydrophilic analogues, such as MnTE-2-PyP5+ and MnTDE-2-ImP5+ are potent in numerous animal models of diseases, the lipophilic analogues were developed to cross blood brain barrier and target central nervous system and critical cellular compartment, mitochondria. The modification of its structure, aimed to preserve the SOD-like potency and lipophilicity, and diminish the toxicity, has presently been pursued. The pulmonary radioprotection by MnTnHex-2-PyP5+ was the first efficacy study performed successfully with non-human primates. The Phase I toxicity clinical trials were done on amyotrophic lateral sclerosis patients with N,N′-diethylimidazolium analogue, MnTDE-2-ImP5+ (AEOL10150). Its aggressive development as a wide spectrum radioprotector by Aeolus Pharmaceuticals has been supported by USA Federal government. The latest generation of compounds, bearing oxygens in pyridyl substituents is presently under aggressive development for cancer and CNS injuries at Duke University and is supported by Duke Translational Research Institute, The Wallace H. Coulter Translational Partners Grant Program, Preston Robert Tisch Brain Tumor Center at Duke, and National Institute of Allergy and Infectious Diseases. Metal center of cationic manganese porphyrins easily accepts and donates electrons as exemplified in the catalysis of O2·− dismutation. Thus such compounds may be equally good anti- and pro-oxidants; in either case the beneficial therapeutic effects may be observed. Moreover, while the in vivo effects may appear antioxidative, the mechanism of action of MnPs that produced such effects may be pro-oxidat...

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Section: Design Of Mn Porphyrins-based Efficacious and Bioavailable Smentioning

confidence: 99%

Diverse functions of cationic Mn(III) N-substituted pyridylporphyrins, recognized as SOD mimics

Batinić‐Haberle

Rajić

Tovmasyan

et al. 2011

Free Radical Biology and Medicine

128

201

View full text Add to dashboard Cite

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“…Straight chain aliphatic compounds are present in them, which get tightly packed at oil-water interface during emulsification as compared with non-Ionic surfactants containing branched chain aliphatic compounds (moderate packing). 24 Stability of O/W emulsions with time is very essential, so that no or very less phase separation occurs during its pipeline transportation. Stability of emulsions depend on a number of factors such as content of water, crude oil, surfactant, and energy requirement in preparation of emulsions.…”

Section: Introductionmentioning

confidence: 99%

Study the influence of sodium dodecyl sulfate on emulsification of heavy and waxy crude oils to improve their flow ability in low temperature conditions

Sharma

Deka

Mandal

et al. 2018

Asia-Pacific J Chem Eng

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Transportation of heavy and waxy crude oils through pipelines is a problem in many regions of the world where low temperatures are observed usually in offshore conditions due to wax and asphaltene precipitation. Transporting them as oil‐in‐water (O/W) emulsion through pipelines is one of the feasible flow assurance solutions. In this research work, O/W emulsions using anionic surfactant sodium dodecyl sulfate are prepared for two Indian crude oil samples having significant asphaltene and wax deposition potential and effect of emulsification on the flow properties of these crude oils are thoroughly analyzed. It is found that the prepared emulsions have very stable phase volume composition up to 50 days at ambient conditions, and they are thermally stable in the temperature range 20–45°C. Emulsions of heavy crude oil are found to be relatively more stable than that of waxy crude with time and temperatures. Fifty percent (v/v) is the observed optimized oil content in the prepared o/w emulsions for both the crude oils at optimum surfactant concentration that is critical micelle concentration (CMC). The prepared emulsions have viscosities as low as 0.01 Pa s and pour point as low as less than 0°C, ensuring easy flow at low temperatures, suited for pipeline transportation at subsea conditions. Interfacial tension and surface tension values of waxy crude‐water system and its o/w emulsions respectively are higher than that of heavy crude‐water system and its O/W emulsions, which indicate difficulty in waxy crude oil transportation compared with heavy crude oil.

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“…The most common method of chemical modification is to first convert the n-alkane to the n-alcohol and then to ethoxylate the alcohol with ethylene oxide (in the presence of a suitable catalyst such as NaOH or KOH) to form a high-molecular weight alcohol ethoxylate that has the following structure: CH 3 -(CH 2 ) n -(O-CH 2 -CH 2 ) m -OH (1) where n is the number of carbon atoms in the hydrocarbon backbone and m is the number of ethylene oxide groups added 1) . With the exception that they are more soluble, the alcohol ethoxylates properties are very similar to the wax they are derived from.…”

Section: Introductionmentioning

confidence: 99%

“…With the exception that they are more soluble, the alcohol ethoxylates properties are very similar to the wax they are derived from. The solubility properties of the wax depend, in addition to the values of m and n, on the ratio of m to n, a higher ratio resulting in a generally increased solubility [1]. Current methods of production [1][2][3][4][5] of alcohol ethoxylates lead to a wide distribution of the number of ethylene oxide units added (i.e., m) and a large quantity of residual alcohol (i.e., m = 0) (see Schwarz [5] for a detailed analysis), yet for many applications a narrow distribution of m with little or no residual alcohol is preferred.…”

Section: Introductionmentioning

confidence: 99%

Concentration of Wax‐like Alcohol Ethoxylates with Supercritical Propane

Schwarz¹,

Nieuwoudt²,

Knoetze³

2007

Chem Eng & Technol

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The virtual insolubility of synthetic wax can be improved by ethoxylating the wax with a polyethylene glycol segment to form an alcohol ethoxylate. Current methods lead to a wide ethylene oxide distribution. This work shows that supercritical propane can fractionate alcohol ethoxylates according to the ethylene oxide content. Solubility measurements in propane at 408 K show total solubility of an alcohol mixture (average 40 carbon atoms) below 140 bar and a region of immiscibility between 0.975 and 0.5 at pressures below 275 bar for the alcohol ethoxylate mixture (average 40 carbon atoms, 50 % ethoxylation). This large solubility difference shows that fractionation of the alcohol ethoxylate with propane is possible. Countercurrent pilot plant runs proved that separation is possible and with energy integration and selection of the correct decompression process the technology is both technically and economically viable.

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Surfactants

Cited by 55 publications

References 95 publications

Diverse functions of cationic Mn(III) N-substituted pyridylporphyrins, recognized as SOD mimics

Diverse functions of cationic Mn(III) N-substituted pyridylporphyrins, recognized as SOD mimics

Study the influence of sodium dodecyl sulfate on emulsification of heavy and waxy crude oils to improve their flow ability in low temperature conditions

Concentration of Wax‐like Alcohol Ethoxylates with Supercritical Propane

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