An argon laser induced polymerization photoinitiated by both mono- and bichromophoric hemicyanine dye-borate salt ion pairs. The synthesis, spectroscopic, electrochemical and kinetic studies

A series of homodimeric hemicyanine dyes based on (p-dimethylaminostyryl)benzothiazolium, (p-dimethylaminostyryl)benzoxazolium, (p-dimethylaminostyryl)-2,3,3-trimethyl-3H-indolium residues were synthesized. Several photoredox pairs containing mono- and bichromophoric hemicyanine dyes, possessing benzothiazole, benzoxazole or indolinium group linked by 5 or 10 methylene groups have been evaluated as novel photoinitiators for free radical polymerization induced with the argon-ion laser visible emission. In tested photoredox pairs, hemicyanine dye acts as an electron acceptor and it is coupled with borate anion which is an electron donor. The photochemistry of the series of bichromophoric hemicyanine borates: 1,5-bis-[N,N′-(2,2′-(4-N,N-dimethylamino)styryl)benzothiazolium]pentane, 1,10-bis-[N,N′-(2,2′-(4-N,N-dimethylamino)styryl)benzothiazolium]decane (S5, S10), 1,5-bis-[N,N′-(2,2′-(4-N,N-dimethylamino)styryl)benzoxazolium]pentane, 1,10-bis-[N,N′-(2,2′-(4-N,N-dimethylamino)styryl)benzoxazolium]decane (O5, O10) and 1,5-bis-[N,N′-(2,2′-(4-N,N-dimethylamino)styryl)-3,3,3′,3′-tetramethyl-3H-indolium]pentane, 1,10-bis-[N,N′-(2,2′-(4-N,N-dimethylamino)styryl)-3,3,3′,3′-tetramethyl-3H-indolium]decane (I5, I10) was compared to the photochemistry of structurally related monochromophoric hemicyanine borates (S1, O1, I1).     

Ring transformation and cyclization reactions of 1,1-dioxo-1,2-thiazines – syntheses of pyridines and benzo[c]thiazines with new substitution pattern

In presence of ammonia/ammonium acetate the 3,5-dimethyl-2-phenyl-1,1-dioxo-1,2-thiazine-4-carbaldehyde ( 1 ) reacts with ethyl cyanoacetate to the ethyl 2-cyano-4-[1-methyl-2-methylthio-2-(N-phenylsulfamoyl)vinyl)-hexa-2,4-dienoate] ( 3 ) and the Knoevenagel condensation product 4-(2-ethoxycarbonyl-2-cyanovinyl)-3,5-dimethyl-6-methylthio-1,1-dioxo-2-phenyl-2H-1,2-thiazine ( 2 a). The 4-(2,2-dicyanovinyl)-3,5-dimethyl-6-methylthio-1,1-dioxo-2-phenyl-2H-1,2-thiazine ( 2b ) is obtained from 1 and malononitril. The masked 1,5-dicarbonyl compound 2a undergoes ring transformation to the 3-cyano-1,6-dimethyl-5-[1-methylthio-2-(N-phenylsulfamoyl)vinyl]pyridin-2-one ( 5 ) with methylamine. With ethanolic ethoxide the condensation products 2a,b afford the 7-amino-6-ethoxycarbonyl-4-methylthio-2,2-dioxo-1-phenyl-benzo[c]1,2-thiazine ( 6a ), respectively the corresponding 6-cyano derivative 6b , while 3 cyclizises to furnish ethyl 2-amino-6-methyl-5-[1-methyl-2-methylthio-2-(N-phenyl-sulfamoyl)vinyl]nicotinate ( 4 ).     

Forgotten monomers: access to α‐modified N‐vinylpyrrolidone polymers via C‐alkylation

Alkylation of N‐vinylpyrrolidone using lithium diisopropylamide and bis(2‐bromoethyl) ether was carried out to obtain 3‐(2‐(2‐bromoethoxy)ethyl)‐1‐vinyl‐2‐pyrrolidone ( 2 ). The derivative 2 represents a versatile starting molecule for further modification via nucleophilic displacement yielding, for example, the bicyclic 2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one ( 4 ) or the ammonium salt 3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone ( 10 ). Via free radical polymerization of 4 and 10 , the corresponding homopolymers were obtained. Copolymerization of 4 and 10 with N,N′‐diethylacrylamide yielded water‐soluble materials. The thermosensitive solubility of copolymers poly[(2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one)‐co‐(N,N′‐diethylacrylamide)] and poly[(3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone)‐co‐(N‐vinylpyrrolidone)] in water was investigated. © 2015 Society of Chemical Industry     

Ionic liquid-based extraction and separation trends of bioactive compounds from plant biomass

Ionic liquids have been projected as the best solvent for extraction and separation of bioactive compounds from various origins. This review offers a collection of the published results, using ionic liquids for the extraction and purification of biomolecules. Ionic liquids have been studied as solvents, co-solvents and supported materials for separation of bioactive compounds. The ionic liquids-based extraction procedures were previously reported, such as ionic liquids-based solid-liquid extraction, liquid-liquid extraction and ionic liquids-modified materials are reviewed and compared to their performance. In this review, the main activities and future challenges are discussed, with major gaps identified using ionic liquids in extraction procedures and by advancing few steps to overcome these drawbacks.

Abbreviation: [(HSO₃)C₄MIM]⁺: 1-(4-sulfonylbutyl)-3-methylimidazolium; [(C₆H₃OCH₂)₂im]⁺: 1,3-dihexyloxymethylimidazolium; [C_nC₁MIM]⁺: 1-alkyl-2,3-dimethylimidazolium; [C_nMIM]^{+; [Cn, 2, 3, 4, 6, 8, 10, 12]}: 1-alkyl-3-methylimidazolium; [C_nC₁pyr]⁺: 1-alkyl-3-methylpyridinium; [C_nim]⁺: 1-alkylimidazolium; [C_npyr]⁺: 1-alkylpyridinium; [aC_nim]⁺: 1-allyl-3-alkylimidazolium; [C₇H₇MIM]⁺: 1-benzyl-3-methylimidazolium; [C₄(C₁C₁C₁Si)im]⁺: 1-butyl-3-trimethylsilylimidazolium; [(HOOC)C₂MIM]⁺: 1-carboxyethyl-3-methylimidazolium; [(OH)C_nMIM]⁺: 1-hydroxyalkyl-3-methylimidazolium; [(C₂H₅O)₃SiC₃MIM]⁺: 1-methyl-3-(triethoxy)silypropyl imidazolium; [(NH₂)C₃MIM]⁺: 1-propylamine-3-methylimidazolium; [C_wH_xN_yO_z]⁺: Chirally functionalized methylimidazolium; [P_{10(3OH)(3OH)(3OH)}]⁺: Decyltris(3-hydrox- ypropyl) phosphonium; [N_111(2OH)]⁺: N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium (cholinium); [N_00nn]⁺: N,N-dialkylammonium; [N_0nn(2OH)]⁺: N,N-dialkyl-N-(2-hydroxyethyl) ammonium; [C₁₀C₁₀C₁gluc]⁺: N,N-didecyl-N-methyl-d-glucaminium; [N_11(2(O)1)0]⁺: N,N-dimethyl(2-methoxyethyl) ammonium; [N_{11(2OH)(C7H7)}]⁺: N-benzyl-N,N-dimethyl-N-(2-hydroxyethyl) ammonium; [P₆₆₆₁₄]⁺: Trihexyltetradecylph- osphonium; [P_i(444)1]⁺: Triisobutyl (methyl) phosphonium; P.minus: Polygonum minus; NPs: Nanoparticle; ZnO : Zinc oxide nanoparticles ; Ni NPs: Nickel nanoparticles; MO: Methyl orange; UAE: Ultrasonic-assisted extraction; LLE: Liquid-liquid extraction; ABS: Aqueous biphasic system ; [Ace]^?: Acesulfamate; [Ala]^?: alalinate; [TMPP]^?: bis(2,4,4-trimethylpentyl)phosphinate; : ; [NTf₂]^?: bis(trifluoromethylsulfonyl)imide; [[Br]^–]: [Br]omide; [Calc]: calkanoate; [Cl]^–: chloride; [Bz]^?: benzoate; [PF₆]^?: hexafluorophosphate; [HSO₄]^?: hydrogenosulfate; [OH]^?: hydroxide; I^–: iodide; [Lac]^?: lactate; [NO₃]^?: nitrate; [[Cl]O₄]^?: perchlorate; [Phe]^?: phenilalaninate; [BF₄]^?: tetrafluoroborate; [SCN]^?: thiocyanate; [C(CN)₃]^?: tricyanomethanide; [CF₃CO₂]^?: trifluoroacetate; [CF₃SO₃]^?: trifluoromethanesulfonate; [FAP]^?: tris(pentafluoroethyl)trifluorophosphate; ILs: Ionic liquids; Ag NPs: Silver nanoparticle; Cu NPs: Copper nanoparticle; MB: Methylene blue; MR: Methyl red ; MAE: Microwave-assisted extraction; SLE: solid-liquid extraction.     

Synthesis and characterization of new aromatic polyesters containing pendent naphthyl units

Two bisphenols, viz., 4,4′‐[1‐(2‐naphthalenyl)ethylidene]bisphenol and 4,4′‐[1‐(2‐naphthalenyl) ethylidene]bis‐3‐methylphenol were prepared by condensation of commercially available 2‐acetonaphthanone with phenol and o‐cresol, respectively. A series of new aromatic polyesters containing pendent naphthyl units was synthesized by phase‐transfer‐catalyzed interfacial polycondensation of these bisphenols with isophthaloyl chloride, terephthaloyl chloride, and a mixture of isophthaloyl chloride/terephthaloyl chloride (50 : 50 mol %). Inherent viscosities of polyesters were in the range 0.83–1.76 dL g⁻¹, while number average molecular weights (M_n) were in the range 61,000–235,000 g mol⁻¹. Polyesters were readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, m‐cresol, pyridine, N,N‐dimethylformamide, N,N‐dimethylacetamide, and 1‐methyl‐2‐pyrrolidinone at room temperature. Tough, transparent, and flexible films were cast from a solution of polyesters in chloroform. X‐Ray diffraction measurements displayed a broad halo at 2θ ≅ 19° indicating the amorphous nature of polyesters. Glass transition temperatures of polyesters were in the range 209–259°C. The temperature at 10% weight loss (T₁₀), determined by TGA in nitrogen atmosphere, of polyesters was in the range 435–500°C indicating their good thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development and applications of quaternary ammonium (QA) membrane electrodes in pharmaceutical preparation and in bioavailability of Prostaglandin E1 and Deoxycholate

The two novel ion-pairs (PB-TPB and NB-TPB) of quaternary ammonium drugs; propantheline bromide (PB), N,N-Diisopropyl-N-methyl-N-[2-(xanthen-9ylcarbonyloxy)ethyl] ammonium bromide and neostigmine bromide (NB), 3-(dimethylcarbamoyloxy) phenyl]-trimethylazanium have been synthesized, respectively and incorporated in poly (vinyl chloride)-based membrane electrodes for the quantification of propantheline bromide and neostigmine bromide in different pharmaceutical preparations. The influences of membrane compositions on the potentiometric responses of membrane electrodes have been found to substantially improve the performance characteristics. The best performance was reported with membranes having composition (w/w) of PB-TPB or NB-TPB (6%): PVC (34%): o-NPOE (60%). The proposed electrodes exhibit nernstian response in the concentration ranges of 2.1 × 10⁻⁷ M to 1.0 × 10⁻² M and 4.4 × 10⁻⁷ M to 1.0 × 10⁻² M with detection limit of 1.5 × 10⁻⁷ M and 3.3 × 10⁻⁷ M, respectively. Both the membrane electrodes perform satisfactorily over pH ranges of (3.5–7.5 and 4.0–7.0) with fast response times (11 s and 13 s), respectively. These drugs (PB and NB) were further utilized as different ion-pairs of Prostaglandin E₁ (PGE₁) and Deoxycholate (DOC) in poly (vinyl chloride)-based membrane electrodes for the determination of bioavailability of Prostaglandin E₁ and Deoxycholate in plasma of different patients.     

Synthesis and Properties of Organosilicon Quaternary Salts Surfactants

Diethyl-benzyl-[3-methyldimethoxyl)]silpropyl ammonium chloride (DEBSAC) was synthesized from N,N-diethyl-aminopropyl-methyldimethoxysilane (DEAPMDES) and benzyl chloride. Diethyl-2,3-epoxypropyl-[3-methyldimethoxyl)] silpropyl ammonium chloride (DEEPSAC) was synthesized from DEAPMDES and epoxy chloropropane. Trimethyl-[3-methyldimethoxyl)] silpropyl ammonium chloride (TMSAC) was synthesized from trimethylamine and γ-chloropropylmethyldimethoxysilane (CPMDMS). The products were characterized by ¹H NMR, ¹³C NMR, and IR. The surface tension measurements showed that the organosilicon quaternary salts exhibit a lower surface tension and a lower critical micelle concentration (CMC) than the hydrocarbon counterparts. The plate count method experiments illustrated that DEEPSAC has a better degree of antibacterial activity against Escherichia coli than DEBSAC. The solubilizing effects of the organosilicon quaternary salts on organosilicone were studied by pseudo-ternary phase diagrams of synthesized products/cosurfactant(n-butanol)/water/octamethylcyclotetrasiloxane. The solubilizing activities decreased in the order of TMSAC > DEBSAC > DEEPSAC.     

Radical polymerization of fumaramide and fumaramate derivatives for homogeneous Langmuir monolayers

Summary The radical polymerization of a series of fumaramides and fumaramates, prepared from the reaction of various amines with fumaroyl dichloride and fumaric chloride isopropyl ester, respectively, was investigated. Although the polymerization reactivity of the N,N,N’,N’-tetrasubstituted fumaramides and N,N-disubstituted fumaramates was low, N-isopropyl fumaramate readily furnished the corresponding high molecular weight polymer. The highest number average molecular weight (M_n) of 15,400 was obtained from the emulsifier-free emulsion polymerization in the presence of VA-086 as the initiator. The decomposition temperature of the obtained polymer was determined to be 299 °C. The π-A isotherm of the polymer indicated the formation of stable Langmuir monolayers with a limiting molecular area (per macromolecular repeating unit) of ca. 26 ?².     

Terpolymer films having semipolar structure: Preparation,wettability, and mechanical properties

A terpolymer, obtained by the free‐radical terpolymerization of 2‐(N,N‐dimethylamino)ethyl methacrylate (DMMA), methyl methacrylate(MMA), and isobutyl methacrylate (IBMA), was allowed to react with hydrogen peroxide, chloroacetic acid, and diethyl sulfate to form the corresponding modified terpolymers: (1) N,N‐dimethyl‐N‐(2‐methacryloyloxyethyl)amine N‐oxide, MMA and IBMA (DMANO series); (2) N‐(carboxymethyl)‐N,N‐dimethyl‐ N‐(2‐methacryloyloxyethyl)ethyl ammonium, MMA and IBMA (CDME series); and (3) N‐(ethyl)‐N,N‐dimethyl‐N‐(2‐methacryloyloxyethyl)ethyl ammonium ethylsulfonate, MMA and IBMA (EDMEES series), respectively. The terpolymer compositions were determined using ¹³C NMR spectrometry. Surface free energies of the terpolymers were estimated by measuring the contact angles of water and methylene iodide on the three series films (DMANO, CDME, and EDMEES), and the effect of the N‐oxide group on wettability was discussed. It was found that the upper surface of the films for the DMANO and CDME series are more hydrophobic than that for the EDMEES series. Notably, elongation to break for the DMANO series was relatively larger than that for the CDME series because of the water bound to the N‐oxide functional group. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1235–1243, 2005     

Hypoxia/Temperature/pH Triple Stimuli–Responsive Block Copolymers: Synthesis,Self-Assembly,and Controlled Drug Release

The amphiphilic block copolymer poly(methacrylic acid-co-2-nitroimidazole acrylate)-b-poly(2-(N,N-dimethylamino)ethyl methacrylate) (P(MAA-co-NIMA)-b-PDMAEMA) with the hypoxia/temperature/pH triple responsiveness is synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT), hydrolysis, and 3-(3-dimethylaminopropyl)-1-ethylcarbodiimide (EDC) reactions, and successfully self-assembled into micelles. The hypoxia response in vitro is realized, and then the sensitivity of the self-assembled micelles to the hypoxia condition is studied by controlling the grafting amount of aminated 2-nitroimidazole. Because 2-(N,N-dimethylamino) ethyl methacrylate (DMAEMA) is a typical material sensitive to temperature and pH conditions, the self-assembled micelles are also responsive to temperature and different acidic/basic conditions. In addition, the cumulative release rate of doxorubicin (DOX) at 42 °C, pH = 6.0, and hypoxic conditions increases significantly, and verifies the synergistic promotion effect of the above stimulations. This intelligent polymer with triple response mechanism improves the controllability and efficiency of drug release, and is expected to be a drug carrier for cancer treatment.     

Pervaporation of aqueous alcohol mixtures through a membrane prepared by grafting of polar monomer onto nylon 4

A hydrophilic pervaporation membrane was prepared via a homografting polymerization of N,N′-(dimethylamino)ethyl methacrylate (DMAEM) onto nylon 4 backbone, DMAEM-g-N4. The water permselectivity was improved by the ammonium quaterization of the pendant N,N′-dimethylamino group on the DMAEM-g-N4 membrane using demethyl sulfate, DMAEMQ-g-N4. The separation factor and permeation rate for both chemically modified nylon 4 membranes were higher than those of the unmodified nylon 4 membrane. The effects of feed composition, feed temperature, and molar volume of the alcohols on pervaporation performance were investigated. Optimum pervaporation was obtained by a DMAEMQ-g-N4 membrane with a degree of grafting of 12.7% for a 90 wt % ethanol feed concentration, giving a separation factor of 36 and a permeation rate of 564 g/m²h. © 1995 John Wiley & Sons, Inc.     

Synthesis and Properties of Three N-Alkyl Bis-Quaternary Ammonium Salt Surfactants

Three N-alkyl bis-quaternary ammonium salt surfactants were synthesized by using epichlorohydrin, trimethylamine hydrochloride, and N,N-dimethylalkyl amine as raw materials in a two-step manner. The products were characterized by ¹H NMR and MS, confirming the successful synthesis of 2-Hydroxy-N¹,N¹,N³,N³-tetramethyl-N³-dodecylpropane-1,3-diammonium chloride (HPDDC), 2-Hydroxy-N¹,N¹,N³,N³-tetramethyl-N³-tetradecylpropane-1,3-diammonium chloride (HPTDC), and 2-Hydroxy-N¹, N¹, N³, N³-tetramethyl-N³-hexadecylpropane-1,3-diammonium chloride (HPHDC). Moreover, the influence of carbon chain length on surface-active properties, foaming properties, and paraffin liquid emulsion stability was investigated. Results indicated that critical micelle concentrations (cmc) decreased with increasing carbon chain length from 12 to 16, and the cmc and γ_cmc were lower than those of Dodecyl trimethyl ammonium chloride (DTAC). The products exhibited better foam properties and worse emulsifying performance than those of DTAC. The Krafft points of all products were determined to be below 0 °C. Moreover, the products also demonstrated outstanding antibacterial properties.     

Highly Selective and Potent Human β-Secretase 2 (BACE2) Inhibitors against Type 2 Diabetes: Design,Synthesis, X-ray Structure and Structure–Activity Relationship Studies

Herein we present the design, synthesis, and biological evaluation of potent and highly selective β-secretase 2 (memapsin 1, beta-site amyloid precursor protein cleaving enzyme 2, or BACE 2) inhibitors. BACE2 has been recognized as an exciting new target for type 2 diabetes. The X-ray structure of BACE1 bound to inhibitor 2 a {N³-[(1S,2R)-1-benzyl-2-hydroxy-3-[[(1S,2S)-2-hydroxy-1-(isobutylcarbamoyl)propyl]amino]propyl]-5-[methyl(methylsulfonyl)amino]-N¹-[(1R)-1-phenylpropyl]benzene-1,3-dicarboxamide} containing a hydroxyethylamine isostere was determined. Based on this structure, a computational docking study was performed which led to inhibitor 2 a -bound BACE2 models. These were used to optimize the potency and selectivity of inhibitors. A systematic structure–activity relationship study led to the identification of determinants of the inhibitors’ potency and selectivity toward the BACE2 enzyme. Inhibitors 2 d [N³-[(1S,2R)-1-benzyl-2-hydroxy-3-[[(1S,2S)-2-hydroxy-1-(isobutylcarbamoyl)pentyl]amino]propyl]-N¹-methyl-N¹-[(1R)-1-phenylpropyl]benzene-1,3-dicarboxamide; K_i=0.031 nm , selectivity over BACE1: ≈174 000-fold] and 3 l [N¹-((2S,3R)-3-hydroxy-1-phenyl-4-((3-(trifluoromethyl)benzyl)amino)butan-2-yl)-N³,5-dimethyl-N³-((R)-1-phenylethyl)isophthalamide; K_i=1.6 nm , selectivity over BACE1: >500-fold] displayed outstanding potency and selectivity. Inhibitor 3 l is nonpeptide in nature and may pave the way to the development of a new class of potent and selective BACE2 inhibitors with clinical potential.     

Coordinate chloride and water-assisted assembly of novel 3D-cageworks of cadmium(II) complex with 4-[N,N-bis(2-cyanoethyl)]aminopyridine

Synthesis and structure of the cadmium(II) complex of [Cd^II(CEAP)₂(H₂O)(CH₃COO)Cl] {CEAP = 4-[N,N-bis(2-cyanoethyl)]aminopyridine} has been reported. The structure exhibits a novel 3D-cagework assembly with the assistance of the coordinated chloride anion and water molecule via forming multiple hydrogen bonds with the cyanoethyl arms of CEAP.     

Antibacterial materials: structure–bioactivity relationship of epoxy–amine resins containing quaternary ammonium compounds covalently attached

Bifunctional aminoalkyldimethylpropylammonium salts (N‐(3‐aminopropyl)‐N,N‐dimethylpentylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyloctylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyldecylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyldodecylammonium chloride) are synthesized and their structure‐dependent antibacterial effect against Gram‐negative Escherichia coli and Gram‐positive Lactococcus lactis is investigated. To this end, resins prepared from bisphenol A diglycidyl ether (2,2‐bis[4‐(glycidyloxy)phenyl]propane) and diethylenetriamine (2,2′‐diaminodiethylamine) as matrix and the bifunctional aminoalkyldimethylpropylammonium salts in a ratio of 6 mol% compared to epoxy components are used. A dependence of antibacterial effect on alkyl chain length of the quaternary ammonium compounds is observed for both species. Furthermore, resins with N‐(3‐aminopropyl)‐N,N‐dimethyldecylammonium chloride in varying concentrations up to 16 mol% for both organisms show a concentration‐dependent antibacterial effect of the quaternary ammonium salt. The antibacterial materials are characterized by differential scanning calorimetry, infrared spectroscopy and rheological studies. © 2013 Society of Chemical Industry     

Effect of some tripodal bipyrazolic compounds on C38 steel corrosion in hydrochloric acid solution

The corrosion inhibition of C38 steel in molar HCl by N,N-bis[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl]buthylamine (P1) and 5-{N,N-bis[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl] amino} pentanol (P2) has been investigated at 308 K using electrochemical and weight loss measurements. Measurements show that these compounds act as good inhibitors without changing the mechanism of the corrosion process. Moreover, the inhibiting efficiency increases with the increase in concentration of the studied inhibitors. Compound P2 showed better protection properties even at relatively higher temperatures when compared to P1. The associated activation corrosion and free adsorption energies have been determined. P1 and P2 are adsorbed on the C38 steel surface according to a Langmuir isotherm adsorption model.     

Corrosion inhibition by N‐(alkyloxycarbonylmethyl)‐N‐triethanol ammonium chloride with respect to the surface and thermodynamic properties

N‐[(octyloxycarbonylmethyl)‐ N‐triethanol ammonium chloride] (C₈ ), N ‐[(dodecyl‐oxycarbonylmethyl)‐ N‐triethanol ammonium chloride] (C₁₂ ) and N ‐[(hexadecyloxycarbonylmethyl)‐N ‐triethanol ammonium chloride] (C₁₆ ) were synthesized. Surface tension was measured in aqueous solution for different concentrations at 28, 38 and 48°C. Various surface properties of the synthesized surfactants were evaluated, particularly critical micelle concentration (CMC), efficiency (Π_CMC) as well as maximum surface excess (Γ_max) and minimum surface area (A_min). Micellization and adsorption in both liquid/air and liquid/solid interfaces thermodynamics were investigated. These products have pronounced surface activity and satisfactory corrosion inhibition of C‐steel in hydrochloric acid at 28, 38 and 48°C. © 1999 Society of Chemical Industry     

Mono‐, Di‐ and Tetra‐Cationic Surfactants as Carbon Steel Corrosion Inhibitors

Corrosion inhibition of three new synthesized cationic surfactants, N‐(2‐(((Z)‐4‐(pyridin‐4‐yl)but‐3‐en‐1‐yl)amino)ethyl)‐N‐(2‐((E)‐(pyridin‐4‐ylmethylene)amino)ethyl)dodecan‐1‐aminium bromide I(4N), N¹,N²‐didodecyl‐N¹‐((Z)‐4‐(pyridin‐4‐yl)but‐3‐en‐1‐yl)‐N²‐(2‐((E)‐(pyridin‐4‐ylmethylene)amino)ethyl)ethane‐1,2‐diaminium bromide II(4N) and 1‐dodecyl‐4‐((E)‐((2‐(dodecyl(2‐(dodecyl((Z)‐4‐(1‐dodecylpyridin‐1‐ium‐4‐yl)but‐3‐en‐1‐yl)ammonio)ethyl)ammonio)ethyl)imino)methyl)pyridin‐1‐ium bromide IV(4N) on carbon steel was investigated by weight loss, electrochemical impedance spectroscopy and polarization measurements. Results show that the synthesized cationic surfactants inhibit corrosion of carbon steel in 1 M HCl. The inhibitive action occurs by virtue of adsorption on the metal surface following a Langmuir adsorption isotherm model. Polarization curves reveal that the investigated cationic surfactants can be classified as mixed inhibitor types. The variations in the corrosion inhibition efficiency between three cationic surfactants are correlated with their chemical structures, with more hydrophobic surfactants yielding higher inhibition efficiency.     

Dispersing multi-walled carbon nanotubes with water-soluble block copolymers and their use as supports for metal nanoparticles

Oxidized multi-walled carbon nanotubes (MWCNTs) were dispersed in aqueous and organic solvents by non-covalent modification with a double-hydrophilic block copolymer, poly(ethylene oxide)-b-poly [2-(N,N-dimethylamino)ethyl methacrylate] (PEO-b-PDMA). The PDMA segments were anchored onto the surface of the oxidized MWCNTs through multi-site zwitterionic interactions between the amino and the carboxyl groups while the PEO segments formed corona to promote the solubility of MWCNTs in different solvents. FT-IR and ¹H NMR spectroscopy gave structural information on the resulting composite, supporting the successful modification. Thermal gravimetric analysis showed that the grafting yield could reach 26%. UV/vis and transmission electron microscopy provided direct evidence for the individual dispersion. The resulting modified MWCNTs could find broad spectrum of applications. As an example, Au and Pt nanoparticles were attached on the sidewall of the modified MWCNTs by using the amino groups of PDMA segments.     

Synthesis of some new fused thiopyrano[2,3-d]thiazoles and their derivatives

A series of some new fused thiopyrano[2,3-d]thiazole derivatives have been synthesized by a stereo-selective hetero-Diels-Alder reaction of 5-(2,4-dihydroxy-benzylidene)-4-thioxo-thiazolidine derivatives 3a,b with acrylonitrile, ethyl acrylate, N-phenylmale-imide, ω-nitrostyrene and N-phenyl-1, 3, 4-triazole-2,5-dione. 5-Amino-9-hydroxy-dihydro-benzopyrano[3′,4′:4,5]thiopyrano[2,3-d]thiazol-6-one derivatives 14a,b have been synthesized by Michael addition of 3a,b with malononitrile. Structures and conceivable mechanisms are discussed.